WSL2-Linux-Kernel/include/linux/atomic.h

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License cleanup: add SPDX GPL-2.0 license identifier to files with no license Many source files in the tree are missing licensing information, which makes it harder for compliance tools to determine the correct license. By default all files without license information are under the default license of the kernel, which is GPL version 2. Update the files which contain no license information with the 'GPL-2.0' SPDX license identifier. The SPDX identifier is a legally binding shorthand, which can be used instead of the full boiler plate text. This patch is based on work done by Thomas Gleixner and Kate Stewart and Philippe Ombredanne. How this work was done: Patches were generated and checked against linux-4.14-rc6 for a subset of the use cases: - file had no licensing information it it. - file was a */uapi/* one with no licensing information in it, - file was a */uapi/* one with existing licensing information, Further patches will be generated in subsequent months to fix up cases where non-standard license headers were used, and references to license had to be inferred by heuristics based on keywords. The analysis to determine which SPDX License Identifier to be applied to a file was done in a spreadsheet of side by side results from of the output of two independent scanners (ScanCode & Windriver) producing SPDX tag:value files created by Philippe Ombredanne. Philippe prepared the base worksheet, and did an initial spot review of a few 1000 files. The 4.13 kernel was the starting point of the analysis with 60,537 files assessed. Kate Stewart did a file by file comparison of the scanner results in the spreadsheet to determine which SPDX license identifier(s) to be applied to the file. She confirmed any determination that was not immediately clear with lawyers working with the Linux Foundation. Criteria used to select files for SPDX license identifier tagging was: - Files considered eligible had to be source code files. - Make and config files were included as candidates if they contained >5 lines of source - File already had some variant of a license header in it (even if <5 lines). All documentation files were explicitly excluded. The following heuristics were used to determine which SPDX license identifiers to apply. - when both scanners couldn't find any license traces, file was considered to have no license information in it, and the top level COPYING file license applied. For non */uapi/* files that summary was: SPDX license identifier # files ---------------------------------------------------|------- GPL-2.0 11139 and resulted in the first patch in this series. If that file was a */uapi/* path one, it was "GPL-2.0 WITH Linux-syscall-note" otherwise it was "GPL-2.0". Results of that was: SPDX license identifier # files ---------------------------------------------------|------- GPL-2.0 WITH Linux-syscall-note 930 and resulted in the second patch in this series. - if a file had some form of licensing information in it, and was one of the */uapi/* ones, it was denoted with the Linux-syscall-note if any GPL family license was found in the file or had no licensing in it (per prior point). Results summary: SPDX license identifier # files ---------------------------------------------------|------ GPL-2.0 WITH Linux-syscall-note 270 GPL-2.0+ WITH Linux-syscall-note 169 ((GPL-2.0 WITH Linux-syscall-note) OR BSD-2-Clause) 21 ((GPL-2.0 WITH Linux-syscall-note) OR BSD-3-Clause) 17 LGPL-2.1+ WITH Linux-syscall-note 15 GPL-1.0+ WITH Linux-syscall-note 14 ((GPL-2.0+ WITH Linux-syscall-note) OR BSD-3-Clause) 5 LGPL-2.0+ WITH Linux-syscall-note 4 LGPL-2.1 WITH Linux-syscall-note 3 ((GPL-2.0 WITH Linux-syscall-note) OR MIT) 3 ((GPL-2.0 WITH Linux-syscall-note) AND MIT) 1 and that resulted in the third patch in this series. - when the two scanners agreed on the detected license(s), that became the concluded license(s). - when there was disagreement between the two scanners (one detected a license but the other didn't, or they both detected different licenses) a manual inspection of the file occurred. - In most cases a manual inspection of the information in the file resulted in a clear resolution of the license that should apply (and which scanner probably needed to revisit its heuristics). - When it was not immediately clear, the license identifier was confirmed with lawyers working with the Linux Foundation. - If there was any question as to the appropriate license identifier, the file was flagged for further research and to be revisited later in time. In total, over 70 hours of logged manual review was done on the spreadsheet to determine the SPDX license identifiers to apply to the source files by Kate, Philippe, Thomas and, in some cases, confirmation by lawyers working with the Linux Foundation. Kate also obtained a third independent scan of the 4.13 code base from FOSSology, and compared selected files where the other two scanners disagreed against that SPDX file, to see if there was new insights. The Windriver scanner is based on an older version of FOSSology in part, so they are related. Thomas did random spot checks in about 500 files from the spreadsheets for the uapi headers and agreed with SPDX license identifier in the files he inspected. For the non-uapi files Thomas did random spot checks in about 15000 files. In initial set of patches against 4.14-rc6, 3 files were found to have copy/paste license identifier errors, and have been fixed to reflect the correct identifier. Additionally Philippe spent 10 hours this week doing a detailed manual inspection and review of the 12,461 patched files from the initial patch version early this week with: - a full scancode scan run, collecting the matched texts, detected license ids and scores - reviewing anything where there was a license detected (about 500+ files) to ensure that the applied SPDX license was correct - reviewing anything where there was no detection but the patch license was not GPL-2.0 WITH Linux-syscall-note to ensure that the applied SPDX license was correct This produced a worksheet with 20 files needing minor correction. This worksheet was then exported into 3 different .csv files for the different types of files to be modified. These .csv files were then reviewed by Greg. Thomas wrote a script to parse the csv files and add the proper SPDX tag to the file, in the format that the file expected. This script was further refined by Greg based on the output to detect more types of files automatically and to distinguish between header and source .c files (which need different comment types.) Finally Greg ran the script using the .csv files to generate the patches. Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org> Reviewed-by: Philippe Ombredanne <pombredanne@nexb.com> Reviewed-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2017-11-01 17:07:57 +03:00
/* SPDX-License-Identifier: GPL-2.0 */
/* Atomic operations usable in machine independent code */
#ifndef _LINUX_ATOMIC_H
#define _LINUX_ATOMIC_H
#include <linux/types.h>
#include <asm/atomic.h>
locking/atomics: Add _{acquire|release|relaxed}() variants of some atomic operations Whilst porting the generic qrwlock code over to arm64, it became apparent that any portable locking code needs finer-grained control of the memory-ordering guarantees provided by our atomic routines. In particular: xchg, cmpxchg, {add,sub}_return are often used in situations where full barrier semantics (currently the only option available) are not required. For example, when a reader increments a reader count to obtain a lock, checking the old value to see if a writer was present, only acquire semantics are strictly needed. This patch introduces three new ordering semantics for these operations: - *_relaxed: No ordering guarantees. This is similar to what we have already for the non-return atomics (e.g. atomic_add). - *_acquire: ACQUIRE semantics, similar to smp_load_acquire. - *_release: RELEASE semantics, similar to smp_store_release. In memory-ordering speak, this means that the acquire/release semantics are RCpc as opposed to RCsc. Consequently a RELEASE followed by an ACQUIRE does not imply a full barrier, as already documented in memory-barriers.txt. Currently, all the new macros are conditionally mapped to the full-mb variants, however if the *_relaxed version is provided by the architecture, then the acquire/release variants are constructed by supplementing the relaxed routine with an explicit barrier. Signed-off-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Waiman.Long@hp.com Cc: paulmck@linux.vnet.ibm.com Link: http://lkml.kernel.org/r/1438880084-18856-2-git-send-email-will.deacon@arm.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-08-06 19:54:37 +03:00
#include <asm/barrier.h>
/*
* Relaxed variants of xchg, cmpxchg and some atomic operations.
*
* We support four variants:
*
* - Fully ordered: The default implementation, no suffix required.
* - Acquire: Provides ACQUIRE semantics, _acquire suffix.
* - Release: Provides RELEASE semantics, _release suffix.
* - Relaxed: No ordering guarantees, _relaxed suffix.
*
* For compound atomics performing both a load and a store, ACQUIRE
* semantics apply only to the load and RELEASE semantics only to the
* store portion of the operation. Note that a failed cmpxchg_acquire
* does -not- imply any memory ordering constraints.
*
* See Documentation/memory-barriers.txt for ACQUIRE/RELEASE definitions.
*/
#ifndef atomic_read_acquire
#define atomic_read_acquire(v) smp_load_acquire(&(v)->counter)
#endif
#ifndef atomic_set_release
#define atomic_set_release(v, i) smp_store_release(&(v)->counter, (i))
#endif
/*
* The idea here is to build acquire/release variants by adding explicit
* barriers on top of the relaxed variant. In the case where the relaxed
* variant is already fully ordered, no additional barriers are needed.
*
locking/atomics: Rework ordering barriers Currently architectures can override __atomic_op_*() to define the barriers used before/after a relaxed atomic when used to build acquire/release/fence variants. This has the unfortunate property of requiring the architecture to define the full wrapper for the atomics, rather than just the barriers they care about, and gets in the way of generating atomics which can be easily read. Instead, this patch has architectures define an optional set of barriers: * __atomic_acquire_fence() * __atomic_release_fence() * __atomic_pre_full_fence() * __atomic_post_full_fence() ... which <linux/atomic.h> uses to build the wrappers. It would be nice if we could undef these, along with the __atomic_op_*() wrappers, but that would break the cmpxchg() wrappers, which are written in preprocessor. Undefs would have been nice, but alas. There should be no functional change as a result of this patch. Signed-off-by: Mark Rutland <mark.rutland@arm.com> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Will Deacon <will.deacon@arm.com> Cc: Andrea Parri <parri.andrea@gmail.com> Cc: Boqun Feng <boqun.feng@gmail.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: andy.shevchenko@gmail.com Cc: arnd@arndb.de Cc: aryabinin@virtuozzo.com Cc: catalin.marinas@arm.com Cc: dvyukov@google.com Cc: glider@google.com Cc: linux-arm-kernel@lists.infradead.org Cc: peter@hurleysoftware.com Link: http://lkml.kernel.org/r/20180716113017.3909-7-mark.rutland@arm.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2018-07-16 14:30:11 +03:00
* If an architecture overrides __atomic_acquire_fence() it will probably
* want to define smp_mb__after_spinlock().
locking/atomics: Add _{acquire|release|relaxed}() variants of some atomic operations Whilst porting the generic qrwlock code over to arm64, it became apparent that any portable locking code needs finer-grained control of the memory-ordering guarantees provided by our atomic routines. In particular: xchg, cmpxchg, {add,sub}_return are often used in situations where full barrier semantics (currently the only option available) are not required. For example, when a reader increments a reader count to obtain a lock, checking the old value to see if a writer was present, only acquire semantics are strictly needed. This patch introduces three new ordering semantics for these operations: - *_relaxed: No ordering guarantees. This is similar to what we have already for the non-return atomics (e.g. atomic_add). - *_acquire: ACQUIRE semantics, similar to smp_load_acquire. - *_release: RELEASE semantics, similar to smp_store_release. In memory-ordering speak, this means that the acquire/release semantics are RCpc as opposed to RCsc. Consequently a RELEASE followed by an ACQUIRE does not imply a full barrier, as already documented in memory-barriers.txt. Currently, all the new macros are conditionally mapped to the full-mb variants, however if the *_relaxed version is provided by the architecture, then the acquire/release variants are constructed by supplementing the relaxed routine with an explicit barrier. Signed-off-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Waiman.Long@hp.com Cc: paulmck@linux.vnet.ibm.com Link: http://lkml.kernel.org/r/1438880084-18856-2-git-send-email-will.deacon@arm.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-08-06 19:54:37 +03:00
*/
locking/atomics: Rework ordering barriers Currently architectures can override __atomic_op_*() to define the barriers used before/after a relaxed atomic when used to build acquire/release/fence variants. This has the unfortunate property of requiring the architecture to define the full wrapper for the atomics, rather than just the barriers they care about, and gets in the way of generating atomics which can be easily read. Instead, this patch has architectures define an optional set of barriers: * __atomic_acquire_fence() * __atomic_release_fence() * __atomic_pre_full_fence() * __atomic_post_full_fence() ... which <linux/atomic.h> uses to build the wrappers. It would be nice if we could undef these, along with the __atomic_op_*() wrappers, but that would break the cmpxchg() wrappers, which are written in preprocessor. Undefs would have been nice, but alas. There should be no functional change as a result of this patch. Signed-off-by: Mark Rutland <mark.rutland@arm.com> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Will Deacon <will.deacon@arm.com> Cc: Andrea Parri <parri.andrea@gmail.com> Cc: Boqun Feng <boqun.feng@gmail.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: andy.shevchenko@gmail.com Cc: arnd@arndb.de Cc: aryabinin@virtuozzo.com Cc: catalin.marinas@arm.com Cc: dvyukov@google.com Cc: glider@google.com Cc: linux-arm-kernel@lists.infradead.org Cc: peter@hurleysoftware.com Link: http://lkml.kernel.org/r/20180716113017.3909-7-mark.rutland@arm.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2018-07-16 14:30:11 +03:00
#ifndef __atomic_acquire_fence
#define __atomic_acquire_fence smp_mb__after_atomic
#endif
#ifndef __atomic_release_fence
#define __atomic_release_fence smp_mb__before_atomic
#endif
#ifndef __atomic_pre_full_fence
#define __atomic_pre_full_fence smp_mb__before_atomic
#endif
#ifndef __atomic_post_full_fence
#define __atomic_post_full_fence smp_mb__after_atomic
#endif
locking/atomics: Add _{acquire|release|relaxed}() variants of some atomic operations Whilst porting the generic qrwlock code over to arm64, it became apparent that any portable locking code needs finer-grained control of the memory-ordering guarantees provided by our atomic routines. In particular: xchg, cmpxchg, {add,sub}_return are often used in situations where full barrier semantics (currently the only option available) are not required. For example, when a reader increments a reader count to obtain a lock, checking the old value to see if a writer was present, only acquire semantics are strictly needed. This patch introduces three new ordering semantics for these operations: - *_relaxed: No ordering guarantees. This is similar to what we have already for the non-return atomics (e.g. atomic_add). - *_acquire: ACQUIRE semantics, similar to smp_load_acquire. - *_release: RELEASE semantics, similar to smp_store_release. In memory-ordering speak, this means that the acquire/release semantics are RCpc as opposed to RCsc. Consequently a RELEASE followed by an ACQUIRE does not imply a full barrier, as already documented in memory-barriers.txt. Currently, all the new macros are conditionally mapped to the full-mb variants, however if the *_relaxed version is provided by the architecture, then the acquire/release variants are constructed by supplementing the relaxed routine with an explicit barrier. Signed-off-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Waiman.Long@hp.com Cc: paulmck@linux.vnet.ibm.com Link: http://lkml.kernel.org/r/1438880084-18856-2-git-send-email-will.deacon@arm.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-08-06 19:54:37 +03:00
#define __atomic_op_acquire(op, args...) \
({ \
typeof(op##_relaxed(args)) __ret = op##_relaxed(args); \
locking/atomics: Rework ordering barriers Currently architectures can override __atomic_op_*() to define the barriers used before/after a relaxed atomic when used to build acquire/release/fence variants. This has the unfortunate property of requiring the architecture to define the full wrapper for the atomics, rather than just the barriers they care about, and gets in the way of generating atomics which can be easily read. Instead, this patch has architectures define an optional set of barriers: * __atomic_acquire_fence() * __atomic_release_fence() * __atomic_pre_full_fence() * __atomic_post_full_fence() ... which <linux/atomic.h> uses to build the wrappers. It would be nice if we could undef these, along with the __atomic_op_*() wrappers, but that would break the cmpxchg() wrappers, which are written in preprocessor. Undefs would have been nice, but alas. There should be no functional change as a result of this patch. Signed-off-by: Mark Rutland <mark.rutland@arm.com> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Will Deacon <will.deacon@arm.com> Cc: Andrea Parri <parri.andrea@gmail.com> Cc: Boqun Feng <boqun.feng@gmail.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: andy.shevchenko@gmail.com Cc: arnd@arndb.de Cc: aryabinin@virtuozzo.com Cc: catalin.marinas@arm.com Cc: dvyukov@google.com Cc: glider@google.com Cc: linux-arm-kernel@lists.infradead.org Cc: peter@hurleysoftware.com Link: http://lkml.kernel.org/r/20180716113017.3909-7-mark.rutland@arm.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2018-07-16 14:30:11 +03:00
__atomic_acquire_fence(); \
locking/atomics: Add _{acquire|release|relaxed}() variants of some atomic operations Whilst porting the generic qrwlock code over to arm64, it became apparent that any portable locking code needs finer-grained control of the memory-ordering guarantees provided by our atomic routines. In particular: xchg, cmpxchg, {add,sub}_return are often used in situations where full barrier semantics (currently the only option available) are not required. For example, when a reader increments a reader count to obtain a lock, checking the old value to see if a writer was present, only acquire semantics are strictly needed. This patch introduces three new ordering semantics for these operations: - *_relaxed: No ordering guarantees. This is similar to what we have already for the non-return atomics (e.g. atomic_add). - *_acquire: ACQUIRE semantics, similar to smp_load_acquire. - *_release: RELEASE semantics, similar to smp_store_release. In memory-ordering speak, this means that the acquire/release semantics are RCpc as opposed to RCsc. Consequently a RELEASE followed by an ACQUIRE does not imply a full barrier, as already documented in memory-barriers.txt. Currently, all the new macros are conditionally mapped to the full-mb variants, however if the *_relaxed version is provided by the architecture, then the acquire/release variants are constructed by supplementing the relaxed routine with an explicit barrier. Signed-off-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Waiman.Long@hp.com Cc: paulmck@linux.vnet.ibm.com Link: http://lkml.kernel.org/r/1438880084-18856-2-git-send-email-will.deacon@arm.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-08-06 19:54:37 +03:00
__ret; \
})
#define __atomic_op_release(op, args...) \
({ \
locking/atomics: Rework ordering barriers Currently architectures can override __atomic_op_*() to define the barriers used before/after a relaxed atomic when used to build acquire/release/fence variants. This has the unfortunate property of requiring the architecture to define the full wrapper for the atomics, rather than just the barriers they care about, and gets in the way of generating atomics which can be easily read. Instead, this patch has architectures define an optional set of barriers: * __atomic_acquire_fence() * __atomic_release_fence() * __atomic_pre_full_fence() * __atomic_post_full_fence() ... which <linux/atomic.h> uses to build the wrappers. It would be nice if we could undef these, along with the __atomic_op_*() wrappers, but that would break the cmpxchg() wrappers, which are written in preprocessor. Undefs would have been nice, but alas. There should be no functional change as a result of this patch. Signed-off-by: Mark Rutland <mark.rutland@arm.com> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Will Deacon <will.deacon@arm.com> Cc: Andrea Parri <parri.andrea@gmail.com> Cc: Boqun Feng <boqun.feng@gmail.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: andy.shevchenko@gmail.com Cc: arnd@arndb.de Cc: aryabinin@virtuozzo.com Cc: catalin.marinas@arm.com Cc: dvyukov@google.com Cc: glider@google.com Cc: linux-arm-kernel@lists.infradead.org Cc: peter@hurleysoftware.com Link: http://lkml.kernel.org/r/20180716113017.3909-7-mark.rutland@arm.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2018-07-16 14:30:11 +03:00
__atomic_release_fence(); \
locking/atomics: Add _{acquire|release|relaxed}() variants of some atomic operations Whilst porting the generic qrwlock code over to arm64, it became apparent that any portable locking code needs finer-grained control of the memory-ordering guarantees provided by our atomic routines. In particular: xchg, cmpxchg, {add,sub}_return are often used in situations where full barrier semantics (currently the only option available) are not required. For example, when a reader increments a reader count to obtain a lock, checking the old value to see if a writer was present, only acquire semantics are strictly needed. This patch introduces three new ordering semantics for these operations: - *_relaxed: No ordering guarantees. This is similar to what we have already for the non-return atomics (e.g. atomic_add). - *_acquire: ACQUIRE semantics, similar to smp_load_acquire. - *_release: RELEASE semantics, similar to smp_store_release. In memory-ordering speak, this means that the acquire/release semantics are RCpc as opposed to RCsc. Consequently a RELEASE followed by an ACQUIRE does not imply a full barrier, as already documented in memory-barriers.txt. Currently, all the new macros are conditionally mapped to the full-mb variants, however if the *_relaxed version is provided by the architecture, then the acquire/release variants are constructed by supplementing the relaxed routine with an explicit barrier. Signed-off-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Waiman.Long@hp.com Cc: paulmck@linux.vnet.ibm.com Link: http://lkml.kernel.org/r/1438880084-18856-2-git-send-email-will.deacon@arm.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-08-06 19:54:37 +03:00
op##_relaxed(args); \
})
#define __atomic_op_fence(op, args...) \
({ \
typeof(op##_relaxed(args)) __ret; \
locking/atomics: Rework ordering barriers Currently architectures can override __atomic_op_*() to define the barriers used before/after a relaxed atomic when used to build acquire/release/fence variants. This has the unfortunate property of requiring the architecture to define the full wrapper for the atomics, rather than just the barriers they care about, and gets in the way of generating atomics which can be easily read. Instead, this patch has architectures define an optional set of barriers: * __atomic_acquire_fence() * __atomic_release_fence() * __atomic_pre_full_fence() * __atomic_post_full_fence() ... which <linux/atomic.h> uses to build the wrappers. It would be nice if we could undef these, along with the __atomic_op_*() wrappers, but that would break the cmpxchg() wrappers, which are written in preprocessor. Undefs would have been nice, but alas. There should be no functional change as a result of this patch. Signed-off-by: Mark Rutland <mark.rutland@arm.com> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Will Deacon <will.deacon@arm.com> Cc: Andrea Parri <parri.andrea@gmail.com> Cc: Boqun Feng <boqun.feng@gmail.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: andy.shevchenko@gmail.com Cc: arnd@arndb.de Cc: aryabinin@virtuozzo.com Cc: catalin.marinas@arm.com Cc: dvyukov@google.com Cc: glider@google.com Cc: linux-arm-kernel@lists.infradead.org Cc: peter@hurleysoftware.com Link: http://lkml.kernel.org/r/20180716113017.3909-7-mark.rutland@arm.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2018-07-16 14:30:11 +03:00
__atomic_pre_full_fence(); \
locking/atomics: Add _{acquire|release|relaxed}() variants of some atomic operations Whilst porting the generic qrwlock code over to arm64, it became apparent that any portable locking code needs finer-grained control of the memory-ordering guarantees provided by our atomic routines. In particular: xchg, cmpxchg, {add,sub}_return are often used in situations where full barrier semantics (currently the only option available) are not required. For example, when a reader increments a reader count to obtain a lock, checking the old value to see if a writer was present, only acquire semantics are strictly needed. This patch introduces three new ordering semantics for these operations: - *_relaxed: No ordering guarantees. This is similar to what we have already for the non-return atomics (e.g. atomic_add). - *_acquire: ACQUIRE semantics, similar to smp_load_acquire. - *_release: RELEASE semantics, similar to smp_store_release. In memory-ordering speak, this means that the acquire/release semantics are RCpc as opposed to RCsc. Consequently a RELEASE followed by an ACQUIRE does not imply a full barrier, as already documented in memory-barriers.txt. Currently, all the new macros are conditionally mapped to the full-mb variants, however if the *_relaxed version is provided by the architecture, then the acquire/release variants are constructed by supplementing the relaxed routine with an explicit barrier. Signed-off-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Waiman.Long@hp.com Cc: paulmck@linux.vnet.ibm.com Link: http://lkml.kernel.org/r/1438880084-18856-2-git-send-email-will.deacon@arm.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-08-06 19:54:37 +03:00
__ret = op##_relaxed(args); \
locking/atomics: Rework ordering barriers Currently architectures can override __atomic_op_*() to define the barriers used before/after a relaxed atomic when used to build acquire/release/fence variants. This has the unfortunate property of requiring the architecture to define the full wrapper for the atomics, rather than just the barriers they care about, and gets in the way of generating atomics which can be easily read. Instead, this patch has architectures define an optional set of barriers: * __atomic_acquire_fence() * __atomic_release_fence() * __atomic_pre_full_fence() * __atomic_post_full_fence() ... which <linux/atomic.h> uses to build the wrappers. It would be nice if we could undef these, along with the __atomic_op_*() wrappers, but that would break the cmpxchg() wrappers, which are written in preprocessor. Undefs would have been nice, but alas. There should be no functional change as a result of this patch. Signed-off-by: Mark Rutland <mark.rutland@arm.com> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Will Deacon <will.deacon@arm.com> Cc: Andrea Parri <parri.andrea@gmail.com> Cc: Boqun Feng <boqun.feng@gmail.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: andy.shevchenko@gmail.com Cc: arnd@arndb.de Cc: aryabinin@virtuozzo.com Cc: catalin.marinas@arm.com Cc: dvyukov@google.com Cc: glider@google.com Cc: linux-arm-kernel@lists.infradead.org Cc: peter@hurleysoftware.com Link: http://lkml.kernel.org/r/20180716113017.3909-7-mark.rutland@arm.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2018-07-16 14:30:11 +03:00
__atomic_post_full_fence(); \
locking/atomics: Add _{acquire|release|relaxed}() variants of some atomic operations Whilst porting the generic qrwlock code over to arm64, it became apparent that any portable locking code needs finer-grained control of the memory-ordering guarantees provided by our atomic routines. In particular: xchg, cmpxchg, {add,sub}_return are often used in situations where full barrier semantics (currently the only option available) are not required. For example, when a reader increments a reader count to obtain a lock, checking the old value to see if a writer was present, only acquire semantics are strictly needed. This patch introduces three new ordering semantics for these operations: - *_relaxed: No ordering guarantees. This is similar to what we have already for the non-return atomics (e.g. atomic_add). - *_acquire: ACQUIRE semantics, similar to smp_load_acquire. - *_release: RELEASE semantics, similar to smp_store_release. In memory-ordering speak, this means that the acquire/release semantics are RCpc as opposed to RCsc. Consequently a RELEASE followed by an ACQUIRE does not imply a full barrier, as already documented in memory-barriers.txt. Currently, all the new macros are conditionally mapped to the full-mb variants, however if the *_relaxed version is provided by the architecture, then the acquire/release variants are constructed by supplementing the relaxed routine with an explicit barrier. Signed-off-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Waiman.Long@hp.com Cc: paulmck@linux.vnet.ibm.com Link: http://lkml.kernel.org/r/1438880084-18856-2-git-send-email-will.deacon@arm.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-08-06 19:54:37 +03:00
__ret; \
})
/* atomic_add_return_relaxed */
#ifndef atomic_add_return_relaxed
#define atomic_add_return_relaxed atomic_add_return
#define atomic_add_return_acquire atomic_add_return
#define atomic_add_return_release atomic_add_return
#else /* atomic_add_return_relaxed */
#ifndef atomic_add_return_acquire
#define atomic_add_return_acquire(...) \
__atomic_op_acquire(atomic_add_return, __VA_ARGS__)
#endif
#ifndef atomic_add_return_release
#define atomic_add_return_release(...) \
__atomic_op_release(atomic_add_return, __VA_ARGS__)
#endif
#ifndef atomic_add_return
#define atomic_add_return(...) \
__atomic_op_fence(atomic_add_return, __VA_ARGS__)
#endif
#endif /* atomic_add_return_relaxed */
#ifndef atomic_inc
#define atomic_inc(v) atomic_add(1, (v))
#endif
/* atomic_inc_return_relaxed */
#ifndef atomic_inc_return_relaxed
#ifndef atomic_inc_return
#define atomic_inc_return(v) atomic_add_return(1, (v))
#define atomic_inc_return_relaxed(v) atomic_add_return_relaxed(1, (v))
#define atomic_inc_return_acquire(v) atomic_add_return_acquire(1, (v))
#define atomic_inc_return_release(v) atomic_add_return_release(1, (v))
#else /* atomic_inc_return */
#define atomic_inc_return_relaxed atomic_inc_return
#define atomic_inc_return_acquire atomic_inc_return
#define atomic_inc_return_release atomic_inc_return
#endif /* atomic_inc_return */
#else /* atomic_inc_return_relaxed */
#ifndef atomic_inc_return_acquire
#define atomic_inc_return_acquire(...) \
__atomic_op_acquire(atomic_inc_return, __VA_ARGS__)
#endif
#ifndef atomic_inc_return_release
#define atomic_inc_return_release(...) \
__atomic_op_release(atomic_inc_return, __VA_ARGS__)
#endif
#ifndef atomic_inc_return
#define atomic_inc_return(...) \
__atomic_op_fence(atomic_inc_return, __VA_ARGS__)
#endif
#endif /* atomic_inc_return_relaxed */
locking/atomics: Add _{acquire|release|relaxed}() variants of some atomic operations Whilst porting the generic qrwlock code over to arm64, it became apparent that any portable locking code needs finer-grained control of the memory-ordering guarantees provided by our atomic routines. In particular: xchg, cmpxchg, {add,sub}_return are often used in situations where full barrier semantics (currently the only option available) are not required. For example, when a reader increments a reader count to obtain a lock, checking the old value to see if a writer was present, only acquire semantics are strictly needed. This patch introduces three new ordering semantics for these operations: - *_relaxed: No ordering guarantees. This is similar to what we have already for the non-return atomics (e.g. atomic_add). - *_acquire: ACQUIRE semantics, similar to smp_load_acquire. - *_release: RELEASE semantics, similar to smp_store_release. In memory-ordering speak, this means that the acquire/release semantics are RCpc as opposed to RCsc. Consequently a RELEASE followed by an ACQUIRE does not imply a full barrier, as already documented in memory-barriers.txt. Currently, all the new macros are conditionally mapped to the full-mb variants, however if the *_relaxed version is provided by the architecture, then the acquire/release variants are constructed by supplementing the relaxed routine with an explicit barrier. Signed-off-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Waiman.Long@hp.com Cc: paulmck@linux.vnet.ibm.com Link: http://lkml.kernel.org/r/1438880084-18856-2-git-send-email-will.deacon@arm.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-08-06 19:54:37 +03:00
/* atomic_sub_return_relaxed */
#ifndef atomic_sub_return_relaxed
#define atomic_sub_return_relaxed atomic_sub_return
#define atomic_sub_return_acquire atomic_sub_return
#define atomic_sub_return_release atomic_sub_return
#else /* atomic_sub_return_relaxed */
#ifndef atomic_sub_return_acquire
#define atomic_sub_return_acquire(...) \
__atomic_op_acquire(atomic_sub_return, __VA_ARGS__)
#endif
#ifndef atomic_sub_return_release
#define atomic_sub_return_release(...) \
__atomic_op_release(atomic_sub_return, __VA_ARGS__)
#endif
#ifndef atomic_sub_return
#define atomic_sub_return(...) \
__atomic_op_fence(atomic_sub_return, __VA_ARGS__)
#endif
#endif /* atomic_sub_return_relaxed */
#ifndef atomic_dec
#define atomic_dec(v) atomic_sub(1, (v))
#endif
/* atomic_dec_return_relaxed */
#ifndef atomic_dec_return_relaxed
#ifndef atomic_dec_return
#define atomic_dec_return(v) atomic_sub_return(1, (v))
#define atomic_dec_return_relaxed(v) atomic_sub_return_relaxed(1, (v))
#define atomic_dec_return_acquire(v) atomic_sub_return_acquire(1, (v))
#define atomic_dec_return_release(v) atomic_sub_return_release(1, (v))
#else /* atomic_dec_return */
#define atomic_dec_return_relaxed atomic_dec_return
#define atomic_dec_return_acquire atomic_dec_return
#define atomic_dec_return_release atomic_dec_return
#endif /* atomic_dec_return */
#else /* atomic_dec_return_relaxed */
#ifndef atomic_dec_return_acquire
#define atomic_dec_return_acquire(...) \
__atomic_op_acquire(atomic_dec_return, __VA_ARGS__)
#endif
#ifndef atomic_dec_return_release
#define atomic_dec_return_release(...) \
__atomic_op_release(atomic_dec_return, __VA_ARGS__)
#endif
#ifndef atomic_dec_return
#define atomic_dec_return(...) \
__atomic_op_fence(atomic_dec_return, __VA_ARGS__)
#endif
#endif /* atomic_dec_return_relaxed */
/* atomic_fetch_add_relaxed */
#ifndef atomic_fetch_add_relaxed
#define atomic_fetch_add_relaxed atomic_fetch_add
#define atomic_fetch_add_acquire atomic_fetch_add
#define atomic_fetch_add_release atomic_fetch_add
#else /* atomic_fetch_add_relaxed */
#ifndef atomic_fetch_add_acquire
#define atomic_fetch_add_acquire(...) \
__atomic_op_acquire(atomic_fetch_add, __VA_ARGS__)
#endif
#ifndef atomic_fetch_add_release
#define atomic_fetch_add_release(...) \
__atomic_op_release(atomic_fetch_add, __VA_ARGS__)
#endif
#ifndef atomic_fetch_add
#define atomic_fetch_add(...) \
__atomic_op_fence(atomic_fetch_add, __VA_ARGS__)
#endif
#endif /* atomic_fetch_add_relaxed */
/* atomic_fetch_inc_relaxed */
#ifndef atomic_fetch_inc_relaxed
#ifndef atomic_fetch_inc
#define atomic_fetch_inc(v) atomic_fetch_add(1, (v))
#define atomic_fetch_inc_relaxed(v) atomic_fetch_add_relaxed(1, (v))
#define atomic_fetch_inc_acquire(v) atomic_fetch_add_acquire(1, (v))
#define atomic_fetch_inc_release(v) atomic_fetch_add_release(1, (v))
#else /* atomic_fetch_inc */
#define atomic_fetch_inc_relaxed atomic_fetch_inc
#define atomic_fetch_inc_acquire atomic_fetch_inc
#define atomic_fetch_inc_release atomic_fetch_inc
#endif /* atomic_fetch_inc */
#else /* atomic_fetch_inc_relaxed */
#ifndef atomic_fetch_inc_acquire
#define atomic_fetch_inc_acquire(...) \
__atomic_op_acquire(atomic_fetch_inc, __VA_ARGS__)
#endif
#ifndef atomic_fetch_inc_release
#define atomic_fetch_inc_release(...) \
__atomic_op_release(atomic_fetch_inc, __VA_ARGS__)
#endif
#ifndef atomic_fetch_inc
#define atomic_fetch_inc(...) \
__atomic_op_fence(atomic_fetch_inc, __VA_ARGS__)
#endif
#endif /* atomic_fetch_inc_relaxed */
/* atomic_fetch_sub_relaxed */
#ifndef atomic_fetch_sub_relaxed
#define atomic_fetch_sub_relaxed atomic_fetch_sub
#define atomic_fetch_sub_acquire atomic_fetch_sub
#define atomic_fetch_sub_release atomic_fetch_sub
#else /* atomic_fetch_sub_relaxed */
#ifndef atomic_fetch_sub_acquire
#define atomic_fetch_sub_acquire(...) \
__atomic_op_acquire(atomic_fetch_sub, __VA_ARGS__)
#endif
#ifndef atomic_fetch_sub_release
#define atomic_fetch_sub_release(...) \
__atomic_op_release(atomic_fetch_sub, __VA_ARGS__)
#endif
#ifndef atomic_fetch_sub
#define atomic_fetch_sub(...) \
__atomic_op_fence(atomic_fetch_sub, __VA_ARGS__)
#endif
#endif /* atomic_fetch_sub_relaxed */
/* atomic_fetch_dec_relaxed */
#ifndef atomic_fetch_dec_relaxed
#ifndef atomic_fetch_dec
#define atomic_fetch_dec(v) atomic_fetch_sub(1, (v))
#define atomic_fetch_dec_relaxed(v) atomic_fetch_sub_relaxed(1, (v))
#define atomic_fetch_dec_acquire(v) atomic_fetch_sub_acquire(1, (v))
#define atomic_fetch_dec_release(v) atomic_fetch_sub_release(1, (v))
#else /* atomic_fetch_dec */
#define atomic_fetch_dec_relaxed atomic_fetch_dec
#define atomic_fetch_dec_acquire atomic_fetch_dec
#define atomic_fetch_dec_release atomic_fetch_dec
#endif /* atomic_fetch_dec */
#else /* atomic_fetch_dec_relaxed */
#ifndef atomic_fetch_dec_acquire
#define atomic_fetch_dec_acquire(...) \
__atomic_op_acquire(atomic_fetch_dec, __VA_ARGS__)
#endif
#ifndef atomic_fetch_dec_release
#define atomic_fetch_dec_release(...) \
__atomic_op_release(atomic_fetch_dec, __VA_ARGS__)
#endif
#ifndef atomic_fetch_dec
#define atomic_fetch_dec(...) \
__atomic_op_fence(atomic_fetch_dec, __VA_ARGS__)
#endif
#endif /* atomic_fetch_dec_relaxed */
/* atomic_fetch_or_relaxed */
#ifndef atomic_fetch_or_relaxed
#define atomic_fetch_or_relaxed atomic_fetch_or
#define atomic_fetch_or_acquire atomic_fetch_or
#define atomic_fetch_or_release atomic_fetch_or
#else /* atomic_fetch_or_relaxed */
#ifndef atomic_fetch_or_acquire
#define atomic_fetch_or_acquire(...) \
__atomic_op_acquire(atomic_fetch_or, __VA_ARGS__)
#endif
#ifndef atomic_fetch_or_release
#define atomic_fetch_or_release(...) \
__atomic_op_release(atomic_fetch_or, __VA_ARGS__)
#endif
#ifndef atomic_fetch_or
#define atomic_fetch_or(...) \
__atomic_op_fence(atomic_fetch_or, __VA_ARGS__)
#endif
#endif /* atomic_fetch_or_relaxed */
/* atomic_fetch_and_relaxed */
#ifndef atomic_fetch_and_relaxed
#define atomic_fetch_and_relaxed atomic_fetch_and
#define atomic_fetch_and_acquire atomic_fetch_and
#define atomic_fetch_and_release atomic_fetch_and
#else /* atomic_fetch_and_relaxed */
#ifndef atomic_fetch_and_acquire
#define atomic_fetch_and_acquire(...) \
__atomic_op_acquire(atomic_fetch_and, __VA_ARGS__)
#endif
#ifndef atomic_fetch_and_release
#define atomic_fetch_and_release(...) \
__atomic_op_release(atomic_fetch_and, __VA_ARGS__)
#endif
#ifndef atomic_fetch_and
#define atomic_fetch_and(...) \
__atomic_op_fence(atomic_fetch_and, __VA_ARGS__)
#endif
#endif /* atomic_fetch_and_relaxed */
#ifndef atomic_andnot
#define atomic_andnot(i, v) atomic_and(~(int)(i), (v))
#endif
#ifndef atomic_fetch_andnot_relaxed
#ifndef atomic_fetch_andnot
#define atomic_fetch_andnot(i, v) atomic_fetch_and(~(int)(i), (v))
#define atomic_fetch_andnot_relaxed(i, v) atomic_fetch_and_relaxed(~(int)(i), (v))
#define atomic_fetch_andnot_acquire(i, v) atomic_fetch_and_acquire(~(int)(i), (v))
#define atomic_fetch_andnot_release(i, v) atomic_fetch_and_release(~(int)(i), (v))
#else /* atomic_fetch_andnot */
#define atomic_fetch_andnot_relaxed atomic_fetch_andnot
#define atomic_fetch_andnot_acquire atomic_fetch_andnot
#define atomic_fetch_andnot_release atomic_fetch_andnot
#endif /* atomic_fetch_andnot */
#else /* atomic_fetch_andnot_relaxed */
#ifndef atomic_fetch_andnot_acquire
#define atomic_fetch_andnot_acquire(...) \
__atomic_op_acquire(atomic_fetch_andnot, __VA_ARGS__)
#endif
#ifndef atomic_fetch_andnot_release
#define atomic_fetch_andnot_release(...) \
__atomic_op_release(atomic_fetch_andnot, __VA_ARGS__)
#endif
#ifndef atomic_fetch_andnot
#define atomic_fetch_andnot(...) \
__atomic_op_fence(atomic_fetch_andnot, __VA_ARGS__)
#endif
#endif /* atomic_fetch_andnot_relaxed */
/* atomic_fetch_xor_relaxed */
#ifndef atomic_fetch_xor_relaxed
#define atomic_fetch_xor_relaxed atomic_fetch_xor
#define atomic_fetch_xor_acquire atomic_fetch_xor
#define atomic_fetch_xor_release atomic_fetch_xor
#else /* atomic_fetch_xor_relaxed */
#ifndef atomic_fetch_xor_acquire
#define atomic_fetch_xor_acquire(...) \
__atomic_op_acquire(atomic_fetch_xor, __VA_ARGS__)
#endif
#ifndef atomic_fetch_xor_release
#define atomic_fetch_xor_release(...) \
__atomic_op_release(atomic_fetch_xor, __VA_ARGS__)
#endif
#ifndef atomic_fetch_xor
#define atomic_fetch_xor(...) \
__atomic_op_fence(atomic_fetch_xor, __VA_ARGS__)
#endif
#endif /* atomic_fetch_xor_relaxed */
locking/atomics: Add _{acquire|release|relaxed}() variants of some atomic operations Whilst porting the generic qrwlock code over to arm64, it became apparent that any portable locking code needs finer-grained control of the memory-ordering guarantees provided by our atomic routines. In particular: xchg, cmpxchg, {add,sub}_return are often used in situations where full barrier semantics (currently the only option available) are not required. For example, when a reader increments a reader count to obtain a lock, checking the old value to see if a writer was present, only acquire semantics are strictly needed. This patch introduces three new ordering semantics for these operations: - *_relaxed: No ordering guarantees. This is similar to what we have already for the non-return atomics (e.g. atomic_add). - *_acquire: ACQUIRE semantics, similar to smp_load_acquire. - *_release: RELEASE semantics, similar to smp_store_release. In memory-ordering speak, this means that the acquire/release semantics are RCpc as opposed to RCsc. Consequently a RELEASE followed by an ACQUIRE does not imply a full barrier, as already documented in memory-barriers.txt. Currently, all the new macros are conditionally mapped to the full-mb variants, however if the *_relaxed version is provided by the architecture, then the acquire/release variants are constructed by supplementing the relaxed routine with an explicit barrier. Signed-off-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Waiman.Long@hp.com Cc: paulmck@linux.vnet.ibm.com Link: http://lkml.kernel.org/r/1438880084-18856-2-git-send-email-will.deacon@arm.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-08-06 19:54:37 +03:00
/* atomic_xchg_relaxed */
#ifndef atomic_xchg_relaxed
#define atomic_xchg_relaxed atomic_xchg
#define atomic_xchg_acquire atomic_xchg
#define atomic_xchg_release atomic_xchg
#else /* atomic_xchg_relaxed */
#ifndef atomic_xchg_acquire
#define atomic_xchg_acquire(...) \
__atomic_op_acquire(atomic_xchg, __VA_ARGS__)
#endif
#ifndef atomic_xchg_release
#define atomic_xchg_release(...) \
__atomic_op_release(atomic_xchg, __VA_ARGS__)
#endif
#ifndef atomic_xchg
#define atomic_xchg(...) \
__atomic_op_fence(atomic_xchg, __VA_ARGS__)
#endif
#endif /* atomic_xchg_relaxed */
/* atomic_cmpxchg_relaxed */
#ifndef atomic_cmpxchg_relaxed
#define atomic_cmpxchg_relaxed atomic_cmpxchg
#define atomic_cmpxchg_acquire atomic_cmpxchg
#define atomic_cmpxchg_release atomic_cmpxchg
#else /* atomic_cmpxchg_relaxed */
#ifndef atomic_cmpxchg_acquire
#define atomic_cmpxchg_acquire(...) \
__atomic_op_acquire(atomic_cmpxchg, __VA_ARGS__)
#endif
#ifndef atomic_cmpxchg_release
#define atomic_cmpxchg_release(...) \
__atomic_op_release(atomic_cmpxchg, __VA_ARGS__)
#endif
#ifndef atomic_cmpxchg
#define atomic_cmpxchg(...) \
__atomic_op_fence(atomic_cmpxchg, __VA_ARGS__)
#endif
#endif /* atomic_cmpxchg_relaxed */
#ifndef atomic_try_cmpxchg
#define __atomic_try_cmpxchg(type, _p, _po, _n) \
({ \
typeof(_po) __po = (_po); \
locking/atomic: Fix atomic_try_cmpxchg() semantics Dmitry noted that the new atomic_try_cmpxchg() primitive is broken when the old pointer doesn't point to the local stack. He writes: "Consider a classical lock-free stack push: node->next = atomic_read(&head); do { } while (!atomic_try_cmpxchg(&head, &node->next, node)); This code is broken with the current implementation, the problem is with unconditional update of *__po. In case of success it writes the same value back into *__po, but in case of cmpxchg success we might have lose ownership of some memory locations and potentially over what __po has pointed to. The same holds for the re-read of *__po. " He also points out that this makes it surprisingly different from the similar C/C++ atomic operation. After investigating the code-gen differences caused by this patch; and a number of alternatives (Linus dislikes this interface lots), we arrived at these results (size x86_64-defconfig/vmlinux): GCC-6.3.0: 10735757 cmpxchg 10726413 try_cmpxchg 10730509 try_cmpxchg + patch 10730445 try_cmpxchg-linus GCC-7 (20170327): 10709514 cmpxchg 10704266 try_cmpxchg 10704266 try_cmpxchg + patch 10704394 try_cmpxchg-linus From this we see that the patch has the advantage of better code-gen on GCC-7 and keeps the interface roughly consistent with the C language variant. Reported-by: Dmitry Vyukov <dvyukov@google.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-kernel@vger.kernel.org Fixes: a9ebf306f52c ("locking/atomic: Introduce atomic_try_cmpxchg()") Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-03-27 14:54:38 +03:00
typeof(*(_po)) __r, __o = *__po; \
__r = atomic_cmpxchg##type((_p), __o, (_n)); \
if (unlikely(__r != __o)) \
*__po = __r; \
likely(__r == __o); \
})
#define atomic_try_cmpxchg(_p, _po, _n) __atomic_try_cmpxchg(, _p, _po, _n)
#define atomic_try_cmpxchg_relaxed(_p, _po, _n) __atomic_try_cmpxchg(_relaxed, _p, _po, _n)
#define atomic_try_cmpxchg_acquire(_p, _po, _n) __atomic_try_cmpxchg(_acquire, _p, _po, _n)
#define atomic_try_cmpxchg_release(_p, _po, _n) __atomic_try_cmpxchg(_release, _p, _po, _n)
#else /* atomic_try_cmpxchg */
#define atomic_try_cmpxchg_relaxed atomic_try_cmpxchg
#define atomic_try_cmpxchg_acquire atomic_try_cmpxchg
#define atomic_try_cmpxchg_release atomic_try_cmpxchg
#endif /* atomic_try_cmpxchg */
locking/atomics: Add _{acquire|release|relaxed}() variants of some atomic operations Whilst porting the generic qrwlock code over to arm64, it became apparent that any portable locking code needs finer-grained control of the memory-ordering guarantees provided by our atomic routines. In particular: xchg, cmpxchg, {add,sub}_return are often used in situations where full barrier semantics (currently the only option available) are not required. For example, when a reader increments a reader count to obtain a lock, checking the old value to see if a writer was present, only acquire semantics are strictly needed. This patch introduces three new ordering semantics for these operations: - *_relaxed: No ordering guarantees. This is similar to what we have already for the non-return atomics (e.g. atomic_add). - *_acquire: ACQUIRE semantics, similar to smp_load_acquire. - *_release: RELEASE semantics, similar to smp_store_release. In memory-ordering speak, this means that the acquire/release semantics are RCpc as opposed to RCsc. Consequently a RELEASE followed by an ACQUIRE does not imply a full barrier, as already documented in memory-barriers.txt. Currently, all the new macros are conditionally mapped to the full-mb variants, however if the *_relaxed version is provided by the architecture, then the acquire/release variants are constructed by supplementing the relaxed routine with an explicit barrier. Signed-off-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Waiman.Long@hp.com Cc: paulmck@linux.vnet.ibm.com Link: http://lkml.kernel.org/r/1438880084-18856-2-git-send-email-will.deacon@arm.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-08-06 19:54:37 +03:00
/* cmpxchg_relaxed */
#ifndef cmpxchg_relaxed
#define cmpxchg_relaxed cmpxchg
#define cmpxchg_acquire cmpxchg
#define cmpxchg_release cmpxchg
#else /* cmpxchg_relaxed */
#ifndef cmpxchg_acquire
#define cmpxchg_acquire(...) \
__atomic_op_acquire(cmpxchg, __VA_ARGS__)
#endif
#ifndef cmpxchg_release
#define cmpxchg_release(...) \
__atomic_op_release(cmpxchg, __VA_ARGS__)
#endif
#ifndef cmpxchg
#define cmpxchg(...) \
__atomic_op_fence(cmpxchg, __VA_ARGS__)
#endif
#endif /* cmpxchg_relaxed */
/* cmpxchg64_relaxed */
#ifndef cmpxchg64_relaxed
#define cmpxchg64_relaxed cmpxchg64
#define cmpxchg64_acquire cmpxchg64
#define cmpxchg64_release cmpxchg64
#else /* cmpxchg64_relaxed */
#ifndef cmpxchg64_acquire
#define cmpxchg64_acquire(...) \
__atomic_op_acquire(cmpxchg64, __VA_ARGS__)
#endif
#ifndef cmpxchg64_release
#define cmpxchg64_release(...) \
__atomic_op_release(cmpxchg64, __VA_ARGS__)
#endif
#ifndef cmpxchg64
#define cmpxchg64(...) \
__atomic_op_fence(cmpxchg64, __VA_ARGS__)
#endif
#endif /* cmpxchg64_relaxed */
/* xchg_relaxed */
#ifndef xchg_relaxed
#define xchg_relaxed xchg
#define xchg_acquire xchg
#define xchg_release xchg
#else /* xchg_relaxed */
#ifndef xchg_acquire
#define xchg_acquire(...) __atomic_op_acquire(xchg, __VA_ARGS__)
#endif
#ifndef xchg_release
#define xchg_release(...) __atomic_op_release(xchg, __VA_ARGS__)
#endif
#ifndef xchg
#define xchg(...) __atomic_op_fence(xchg, __VA_ARGS__)
#endif
#endif /* xchg_relaxed */
/**
* atomic_fetch_add_unless - add unless the number is already a given value
* @v: pointer of type atomic_t
* @a: the amount to add to v...
* @u: ...unless v is equal to u.
*
* Atomically adds @a to @v, if @v was not already @u.
* Returns the original value of @v.
*/
#ifndef atomic_fetch_add_unless
static inline int atomic_fetch_add_unless(atomic_t *v, int a, int u)
{
int c = atomic_read(v);
do {
if (unlikely(c == u))
break;
} while (!atomic_try_cmpxchg(v, &c, c + a));
return c;
}
#endif
/**
* atomic_add_unless - add unless the number is already a given value
* @v: pointer of type atomic_t
* @a: the amount to add to v...
* @u: ...unless v is equal to u.
*
* Atomically adds @a to @v, if @v was not already @u.
* Returns true if the addition was done.
*/
static inline bool atomic_add_unless(atomic_t *v, int a, int u)
{
atomics/treewide: Rename __atomic_add_unless() => atomic_fetch_add_unless() While __atomic_add_unless() was originally intended as a building-block for atomic_add_unless(), it's now used in a number of places around the kernel. It's the only common atomic operation named __atomic*(), rather than atomic_*(), and for consistency it would be better named atomic_fetch_add_unless(). This lack of consistency is slightly confusing, and gets in the way of scripting atomics. Given that, let's clean things up and promote it to an official part of the atomics API, in the form of atomic_fetch_add_unless(). This patch converts definitions and invocations over to the new name, including the instrumented version, using the following script: ---- git grep -w __atomic_add_unless | while read line; do sed -i '{s/\<__atomic_add_unless\>/atomic_fetch_add_unless/}' "${line%%:*}"; done git grep -w __arch_atomic_add_unless | while read line; do sed -i '{s/\<__arch_atomic_add_unless\>/arch_atomic_fetch_add_unless/}' "${line%%:*}"; done ---- Note that we do not have atomic{64,_long}_fetch_add_unless(), which will be introduced by later patches. There should be no functional change as a result of this patch. Signed-off-by: Mark Rutland <mark.rutland@arm.com> Reviewed-by: Will Deacon <will.deacon@arm.com> Acked-by: Geert Uytterhoeven <geert@linux-m68k.org> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Palmer Dabbelt <palmer@sifive.com> Cc: Boqun Feng <boqun.feng@gmail.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: https://lore.kernel.org/lkml/20180621121321.4761-2-mark.rutland@arm.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2018-06-21 15:13:04 +03:00
return atomic_fetch_add_unless(v, a, u) != u;
}
/**
* atomic_inc_not_zero - increment unless the number is zero
* @v: pointer of type atomic_t
*
* Atomically increments @v by 1, if @v is non-zero.
* Returns true if the increment was done.
*/
#ifndef atomic_inc_not_zero
#define atomic_inc_not_zero(v) atomic_add_unless((v), 1, 0)
#endif
2018-06-21 15:13:18 +03:00
/**
* atomic_inc_and_test - increment and test
* @v: pointer of type atomic_t
*
* Atomically increments @v by 1
* and returns true if the result is zero, or false for all
* other cases.
*/
#ifndef atomic_inc_and_test
static inline bool atomic_inc_and_test(atomic_t *v)
{
return atomic_inc_return(v) == 0;
}
#endif
/**
* atomic_dec_and_test - decrement and test
* @v: pointer of type atomic_t
*
* Atomically decrements @v by 1 and
* returns true if the result is 0, or false for all other
* cases.
*/
#ifndef atomic_dec_and_test
static inline bool atomic_dec_and_test(atomic_t *v)
{
return atomic_dec_return(v) == 0;
}
#endif
/**
* atomic_sub_and_test - subtract value from variable and test result
* @i: integer value to subtract
* @v: pointer of type atomic_t
*
* Atomically subtracts @i from @v and returns
* true if the result is zero, or false for all
* other cases.
*/
#ifndef atomic_sub_and_test
static inline bool atomic_sub_and_test(int i, atomic_t *v)
{
return atomic_sub_return(i, v) == 0;
}
#endif
/**
* atomic_add_negative - add and test if negative
* @i: integer value to add
* @v: pointer of type atomic_t
*
* Atomically adds @i to @v and returns true
* if the result is negative, or false when
* result is greater than or equal to zero.
*/
#ifndef atomic_add_negative
static inline bool atomic_add_negative(int i, atomic_t *v)
{
return atomic_add_return(i, v) < 0;
}
#endif
#ifndef atomic_inc_unless_negative
static inline bool atomic_inc_unless_negative(atomic_t *v)
{
int c = atomic_read(v);
do {
if (unlikely(c < 0))
return false;
} while (!atomic_try_cmpxchg(v, &c, c + 1));
return true;
}
#endif
#ifndef atomic_dec_unless_positive
static inline bool atomic_dec_unless_positive(atomic_t *v)
{
int c = atomic_read(v);
do {
if (unlikely(c > 0))
return false;
} while (!atomic_try_cmpxchg(v, &c, c - 1));
return true;
}
#endif
/*
* atomic_dec_if_positive - decrement by 1 if old value positive
* @v: pointer of type atomic_t
*
* The function returns the old value of *v minus 1, even if
* the atomic variable, v, was not decremented.
*/
#ifndef atomic_dec_if_positive
static inline int atomic_dec_if_positive(atomic_t *v)
{
int dec, c = atomic_read(v);
do {
dec = c - 1;
if (unlikely(dec < 0))
break;
} while (!atomic_try_cmpxchg(v, &c, dec));
return dec;
}
#endif
#define atomic_cond_read_relaxed(v, c) smp_cond_load_relaxed(&(v)->counter, (c))
#define atomic_cond_read_acquire(v, c) smp_cond_load_acquire(&(v)->counter, (c))
#ifdef CONFIG_GENERIC_ATOMIC64
#include <asm-generic/atomic64.h>
#endif
#ifndef atomic64_read_acquire
#define atomic64_read_acquire(v) smp_load_acquire(&(v)->counter)
#endif
#ifndef atomic64_set_release
#define atomic64_set_release(v, i) smp_store_release(&(v)->counter, (i))
#endif
/* atomic64_add_return_relaxed */
#ifndef atomic64_add_return_relaxed
#define atomic64_add_return_relaxed atomic64_add_return
#define atomic64_add_return_acquire atomic64_add_return
#define atomic64_add_return_release atomic64_add_return
#else /* atomic64_add_return_relaxed */
#ifndef atomic64_add_return_acquire
#define atomic64_add_return_acquire(...) \
__atomic_op_acquire(atomic64_add_return, __VA_ARGS__)
#endif
#ifndef atomic64_add_return_release
#define atomic64_add_return_release(...) \
__atomic_op_release(atomic64_add_return, __VA_ARGS__)
#endif
#ifndef atomic64_add_return
#define atomic64_add_return(...) \
__atomic_op_fence(atomic64_add_return, __VA_ARGS__)
#endif
#endif /* atomic64_add_return_relaxed */
#ifndef atomic64_inc
#define atomic64_inc(v) atomic64_add(1, (v))
#endif
/* atomic64_inc_return_relaxed */
#ifndef atomic64_inc_return_relaxed
#ifndef atomic64_inc_return
#define atomic64_inc_return(v) atomic64_add_return(1, (v))
#define atomic64_inc_return_relaxed(v) atomic64_add_return_relaxed(1, (v))
#define atomic64_inc_return_acquire(v) atomic64_add_return_acquire(1, (v))
#define atomic64_inc_return_release(v) atomic64_add_return_release(1, (v))
#else /* atomic64_inc_return */
#define atomic64_inc_return_relaxed atomic64_inc_return
#define atomic64_inc_return_acquire atomic64_inc_return
#define atomic64_inc_return_release atomic64_inc_return
#endif /* atomic64_inc_return */
#else /* atomic64_inc_return_relaxed */
#ifndef atomic64_inc_return_acquire
#define atomic64_inc_return_acquire(...) \
__atomic_op_acquire(atomic64_inc_return, __VA_ARGS__)
#endif
#ifndef atomic64_inc_return_release
#define atomic64_inc_return_release(...) \
__atomic_op_release(atomic64_inc_return, __VA_ARGS__)
#endif
#ifndef atomic64_inc_return
#define atomic64_inc_return(...) \
__atomic_op_fence(atomic64_inc_return, __VA_ARGS__)
#endif
#endif /* atomic64_inc_return_relaxed */
/* atomic64_sub_return_relaxed */
#ifndef atomic64_sub_return_relaxed
#define atomic64_sub_return_relaxed atomic64_sub_return
#define atomic64_sub_return_acquire atomic64_sub_return
#define atomic64_sub_return_release atomic64_sub_return
#else /* atomic64_sub_return_relaxed */
#ifndef atomic64_sub_return_acquire
#define atomic64_sub_return_acquire(...) \
__atomic_op_acquire(atomic64_sub_return, __VA_ARGS__)
#endif
#ifndef atomic64_sub_return_release
#define atomic64_sub_return_release(...) \
__atomic_op_release(atomic64_sub_return, __VA_ARGS__)
#endif
#ifndef atomic64_sub_return
#define atomic64_sub_return(...) \
__atomic_op_fence(atomic64_sub_return, __VA_ARGS__)
#endif
#endif /* atomic64_sub_return_relaxed */
#ifndef atomic64_dec
#define atomic64_dec(v) atomic64_sub(1, (v))
#endif
/* atomic64_dec_return_relaxed */
#ifndef atomic64_dec_return_relaxed
#ifndef atomic64_dec_return
#define atomic64_dec_return(v) atomic64_sub_return(1, (v))
#define atomic64_dec_return_relaxed(v) atomic64_sub_return_relaxed(1, (v))
#define atomic64_dec_return_acquire(v) atomic64_sub_return_acquire(1, (v))
#define atomic64_dec_return_release(v) atomic64_sub_return_release(1, (v))
#else /* atomic64_dec_return */
#define atomic64_dec_return_relaxed atomic64_dec_return
#define atomic64_dec_return_acquire atomic64_dec_return
#define atomic64_dec_return_release atomic64_dec_return
#endif /* atomic64_dec_return */
#else /* atomic64_dec_return_relaxed */
#ifndef atomic64_dec_return_acquire
#define atomic64_dec_return_acquire(...) \
__atomic_op_acquire(atomic64_dec_return, __VA_ARGS__)
#endif
#ifndef atomic64_dec_return_release
#define atomic64_dec_return_release(...) \
__atomic_op_release(atomic64_dec_return, __VA_ARGS__)
#endif
#ifndef atomic64_dec_return
#define atomic64_dec_return(...) \
__atomic_op_fence(atomic64_dec_return, __VA_ARGS__)
#endif
#endif /* atomic64_dec_return_relaxed */
/* atomic64_fetch_add_relaxed */
#ifndef atomic64_fetch_add_relaxed
#define atomic64_fetch_add_relaxed atomic64_fetch_add
#define atomic64_fetch_add_acquire atomic64_fetch_add
#define atomic64_fetch_add_release atomic64_fetch_add
#else /* atomic64_fetch_add_relaxed */
#ifndef atomic64_fetch_add_acquire
#define atomic64_fetch_add_acquire(...) \
__atomic_op_acquire(atomic64_fetch_add, __VA_ARGS__)
#endif
#ifndef atomic64_fetch_add_release
#define atomic64_fetch_add_release(...) \
__atomic_op_release(atomic64_fetch_add, __VA_ARGS__)
#endif
#ifndef atomic64_fetch_add
#define atomic64_fetch_add(...) \
__atomic_op_fence(atomic64_fetch_add, __VA_ARGS__)
#endif
#endif /* atomic64_fetch_add_relaxed */
/* atomic64_fetch_inc_relaxed */
#ifndef atomic64_fetch_inc_relaxed
#ifndef atomic64_fetch_inc
#define atomic64_fetch_inc(v) atomic64_fetch_add(1, (v))
#define atomic64_fetch_inc_relaxed(v) atomic64_fetch_add_relaxed(1, (v))
#define atomic64_fetch_inc_acquire(v) atomic64_fetch_add_acquire(1, (v))
#define atomic64_fetch_inc_release(v) atomic64_fetch_add_release(1, (v))
#else /* atomic64_fetch_inc */
#define atomic64_fetch_inc_relaxed atomic64_fetch_inc
#define atomic64_fetch_inc_acquire atomic64_fetch_inc
#define atomic64_fetch_inc_release atomic64_fetch_inc
#endif /* atomic64_fetch_inc */
#else /* atomic64_fetch_inc_relaxed */
#ifndef atomic64_fetch_inc_acquire
#define atomic64_fetch_inc_acquire(...) \
__atomic_op_acquire(atomic64_fetch_inc, __VA_ARGS__)
#endif
#ifndef atomic64_fetch_inc_release
#define atomic64_fetch_inc_release(...) \
__atomic_op_release(atomic64_fetch_inc, __VA_ARGS__)
#endif
#ifndef atomic64_fetch_inc
#define atomic64_fetch_inc(...) \
__atomic_op_fence(atomic64_fetch_inc, __VA_ARGS__)
#endif
#endif /* atomic64_fetch_inc_relaxed */
/* atomic64_fetch_sub_relaxed */
#ifndef atomic64_fetch_sub_relaxed
#define atomic64_fetch_sub_relaxed atomic64_fetch_sub
#define atomic64_fetch_sub_acquire atomic64_fetch_sub
#define atomic64_fetch_sub_release atomic64_fetch_sub
#else /* atomic64_fetch_sub_relaxed */
#ifndef atomic64_fetch_sub_acquire
#define atomic64_fetch_sub_acquire(...) \
__atomic_op_acquire(atomic64_fetch_sub, __VA_ARGS__)
#endif
#ifndef atomic64_fetch_sub_release
#define atomic64_fetch_sub_release(...) \
__atomic_op_release(atomic64_fetch_sub, __VA_ARGS__)
#endif
#ifndef atomic64_fetch_sub
#define atomic64_fetch_sub(...) \
__atomic_op_fence(atomic64_fetch_sub, __VA_ARGS__)
#endif
#endif /* atomic64_fetch_sub_relaxed */
/* atomic64_fetch_dec_relaxed */
#ifndef atomic64_fetch_dec_relaxed
#ifndef atomic64_fetch_dec
#define atomic64_fetch_dec(v) atomic64_fetch_sub(1, (v))
#define atomic64_fetch_dec_relaxed(v) atomic64_fetch_sub_relaxed(1, (v))
#define atomic64_fetch_dec_acquire(v) atomic64_fetch_sub_acquire(1, (v))
#define atomic64_fetch_dec_release(v) atomic64_fetch_sub_release(1, (v))
#else /* atomic64_fetch_dec */
#define atomic64_fetch_dec_relaxed atomic64_fetch_dec
#define atomic64_fetch_dec_acquire atomic64_fetch_dec
#define atomic64_fetch_dec_release atomic64_fetch_dec
#endif /* atomic64_fetch_dec */
#else /* atomic64_fetch_dec_relaxed */
#ifndef atomic64_fetch_dec_acquire
#define atomic64_fetch_dec_acquire(...) \
__atomic_op_acquire(atomic64_fetch_dec, __VA_ARGS__)
#endif
#ifndef atomic64_fetch_dec_release
#define atomic64_fetch_dec_release(...) \
__atomic_op_release(atomic64_fetch_dec, __VA_ARGS__)
#endif
#ifndef atomic64_fetch_dec
#define atomic64_fetch_dec(...) \
__atomic_op_fence(atomic64_fetch_dec, __VA_ARGS__)
#endif
#endif /* atomic64_fetch_dec_relaxed */
/* atomic64_fetch_or_relaxed */
#ifndef atomic64_fetch_or_relaxed
#define atomic64_fetch_or_relaxed atomic64_fetch_or
#define atomic64_fetch_or_acquire atomic64_fetch_or
#define atomic64_fetch_or_release atomic64_fetch_or
#else /* atomic64_fetch_or_relaxed */
#ifndef atomic64_fetch_or_acquire
#define atomic64_fetch_or_acquire(...) \
__atomic_op_acquire(atomic64_fetch_or, __VA_ARGS__)
#endif
#ifndef atomic64_fetch_or_release
#define atomic64_fetch_or_release(...) \
__atomic_op_release(atomic64_fetch_or, __VA_ARGS__)
#endif
#ifndef atomic64_fetch_or
#define atomic64_fetch_or(...) \
__atomic_op_fence(atomic64_fetch_or, __VA_ARGS__)
#endif
#endif /* atomic64_fetch_or_relaxed */
/* atomic64_fetch_and_relaxed */
#ifndef atomic64_fetch_and_relaxed
#define atomic64_fetch_and_relaxed atomic64_fetch_and
#define atomic64_fetch_and_acquire atomic64_fetch_and
#define atomic64_fetch_and_release atomic64_fetch_and
#else /* atomic64_fetch_and_relaxed */
#ifndef atomic64_fetch_and_acquire
#define atomic64_fetch_and_acquire(...) \
__atomic_op_acquire(atomic64_fetch_and, __VA_ARGS__)
#endif
#ifndef atomic64_fetch_and_release
#define atomic64_fetch_and_release(...) \
__atomic_op_release(atomic64_fetch_and, __VA_ARGS__)
#endif
#ifndef atomic64_fetch_and
#define atomic64_fetch_and(...) \
__atomic_op_fence(atomic64_fetch_and, __VA_ARGS__)
#endif
#endif /* atomic64_fetch_and_relaxed */
#ifndef atomic64_andnot
#define atomic64_andnot(i, v) atomic64_and(~(long long)(i), (v))
#endif
#ifndef atomic64_fetch_andnot_relaxed
#ifndef atomic64_fetch_andnot
#define atomic64_fetch_andnot(i, v) atomic64_fetch_and(~(long long)(i), (v))
#define atomic64_fetch_andnot_relaxed(i, v) atomic64_fetch_and_relaxed(~(long long)(i), (v))
#define atomic64_fetch_andnot_acquire(i, v) atomic64_fetch_and_acquire(~(long long)(i), (v))
#define atomic64_fetch_andnot_release(i, v) atomic64_fetch_and_release(~(long long)(i), (v))
#else /* atomic64_fetch_andnot */
#define atomic64_fetch_andnot_relaxed atomic64_fetch_andnot
#define atomic64_fetch_andnot_acquire atomic64_fetch_andnot
#define atomic64_fetch_andnot_release atomic64_fetch_andnot
#endif /* atomic64_fetch_andnot */
#else /* atomic64_fetch_andnot_relaxed */
#ifndef atomic64_fetch_andnot_acquire
#define atomic64_fetch_andnot_acquire(...) \
__atomic_op_acquire(atomic64_fetch_andnot, __VA_ARGS__)
#endif
#ifndef atomic64_fetch_andnot_release
#define atomic64_fetch_andnot_release(...) \
__atomic_op_release(atomic64_fetch_andnot, __VA_ARGS__)
#endif
#ifndef atomic64_fetch_andnot
#define atomic64_fetch_andnot(...) \
__atomic_op_fence(atomic64_fetch_andnot, __VA_ARGS__)
#endif
#endif /* atomic64_fetch_andnot_relaxed */
/* atomic64_fetch_xor_relaxed */
#ifndef atomic64_fetch_xor_relaxed
#define atomic64_fetch_xor_relaxed atomic64_fetch_xor
#define atomic64_fetch_xor_acquire atomic64_fetch_xor
#define atomic64_fetch_xor_release atomic64_fetch_xor
#else /* atomic64_fetch_xor_relaxed */
#ifndef atomic64_fetch_xor_acquire
#define atomic64_fetch_xor_acquire(...) \
__atomic_op_acquire(atomic64_fetch_xor, __VA_ARGS__)
#endif
#ifndef atomic64_fetch_xor_release
#define atomic64_fetch_xor_release(...) \
__atomic_op_release(atomic64_fetch_xor, __VA_ARGS__)
#endif
#ifndef atomic64_fetch_xor
#define atomic64_fetch_xor(...) \
__atomic_op_fence(atomic64_fetch_xor, __VA_ARGS__)
#endif
#endif /* atomic64_fetch_xor_relaxed */
/* atomic64_xchg_relaxed */
#ifndef atomic64_xchg_relaxed
#define atomic64_xchg_relaxed atomic64_xchg
#define atomic64_xchg_acquire atomic64_xchg
#define atomic64_xchg_release atomic64_xchg
#else /* atomic64_xchg_relaxed */
#ifndef atomic64_xchg_acquire
#define atomic64_xchg_acquire(...) \
__atomic_op_acquire(atomic64_xchg, __VA_ARGS__)
#endif
#ifndef atomic64_xchg_release
#define atomic64_xchg_release(...) \
__atomic_op_release(atomic64_xchg, __VA_ARGS__)
#endif
#ifndef atomic64_xchg
#define atomic64_xchg(...) \
__atomic_op_fence(atomic64_xchg, __VA_ARGS__)
#endif
#endif /* atomic64_xchg_relaxed */
/* atomic64_cmpxchg_relaxed */
#ifndef atomic64_cmpxchg_relaxed
#define atomic64_cmpxchg_relaxed atomic64_cmpxchg
#define atomic64_cmpxchg_acquire atomic64_cmpxchg
#define atomic64_cmpxchg_release atomic64_cmpxchg
#else /* atomic64_cmpxchg_relaxed */
#ifndef atomic64_cmpxchg_acquire
#define atomic64_cmpxchg_acquire(...) \
__atomic_op_acquire(atomic64_cmpxchg, __VA_ARGS__)
#endif
#ifndef atomic64_cmpxchg_release
#define atomic64_cmpxchg_release(...) \
__atomic_op_release(atomic64_cmpxchg, __VA_ARGS__)
#endif
#ifndef atomic64_cmpxchg
#define atomic64_cmpxchg(...) \
__atomic_op_fence(atomic64_cmpxchg, __VA_ARGS__)
#endif
#endif /* atomic64_cmpxchg_relaxed */
#ifndef atomic64_try_cmpxchg
#define __atomic64_try_cmpxchg(type, _p, _po, _n) \
({ \
typeof(_po) __po = (_po); \
locking/atomic: Fix atomic_try_cmpxchg() semantics Dmitry noted that the new atomic_try_cmpxchg() primitive is broken when the old pointer doesn't point to the local stack. He writes: "Consider a classical lock-free stack push: node->next = atomic_read(&head); do { } while (!atomic_try_cmpxchg(&head, &node->next, node)); This code is broken with the current implementation, the problem is with unconditional update of *__po. In case of success it writes the same value back into *__po, but in case of cmpxchg success we might have lose ownership of some memory locations and potentially over what __po has pointed to. The same holds for the re-read of *__po. " He also points out that this makes it surprisingly different from the similar C/C++ atomic operation. After investigating the code-gen differences caused by this patch; and a number of alternatives (Linus dislikes this interface lots), we arrived at these results (size x86_64-defconfig/vmlinux): GCC-6.3.0: 10735757 cmpxchg 10726413 try_cmpxchg 10730509 try_cmpxchg + patch 10730445 try_cmpxchg-linus GCC-7 (20170327): 10709514 cmpxchg 10704266 try_cmpxchg 10704266 try_cmpxchg + patch 10704394 try_cmpxchg-linus From this we see that the patch has the advantage of better code-gen on GCC-7 and keeps the interface roughly consistent with the C language variant. Reported-by: Dmitry Vyukov <dvyukov@google.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-kernel@vger.kernel.org Fixes: a9ebf306f52c ("locking/atomic: Introduce atomic_try_cmpxchg()") Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-03-27 14:54:38 +03:00
typeof(*(_po)) __r, __o = *__po; \
__r = atomic64_cmpxchg##type((_p), __o, (_n)); \
if (unlikely(__r != __o)) \
*__po = __r; \
likely(__r == __o); \
})
#define atomic64_try_cmpxchg(_p, _po, _n) __atomic64_try_cmpxchg(, _p, _po, _n)
#define atomic64_try_cmpxchg_relaxed(_p, _po, _n) __atomic64_try_cmpxchg(_relaxed, _p, _po, _n)
#define atomic64_try_cmpxchg_acquire(_p, _po, _n) __atomic64_try_cmpxchg(_acquire, _p, _po, _n)
#define atomic64_try_cmpxchg_release(_p, _po, _n) __atomic64_try_cmpxchg(_release, _p, _po, _n)
#else /* atomic64_try_cmpxchg */
#define atomic64_try_cmpxchg_relaxed atomic64_try_cmpxchg
#define atomic64_try_cmpxchg_acquire atomic64_try_cmpxchg
#define atomic64_try_cmpxchg_release atomic64_try_cmpxchg
#endif /* atomic64_try_cmpxchg */
/**
* atomic64_fetch_add_unless - add unless the number is already a given value
* @v: pointer of type atomic64_t
* @a: the amount to add to v...
* @u: ...unless v is equal to u.
*
* Atomically adds @a to @v, if @v was not already @u.
* Returns the original value of @v.
*/
#ifndef atomic64_fetch_add_unless
static inline long long atomic64_fetch_add_unless(atomic64_t *v, long long a,
long long u)
{
long long c = atomic64_read(v);
do {
if (unlikely(c == u))
break;
} while (!atomic64_try_cmpxchg(v, &c, c + a));
return c;
}
#endif
atomics: Prepare for atomic64_fetch_add_unless() Currently all architectures must implement atomic_fetch_add_unless(), with common code providing atomic_add_unless(). Architectures must also implement atomic64_add_unless() directly, with no corresponding atomic64_fetch_add_unless(). This divergence is unfortunate, and means that the APIs for atomic_t, atomic64_t, and atomic_long_t differ. In preparation for unifying things, with architectures providing atomic64_fetch_add_unless, this patch adds a generic atomic64_add_unless() which will use atomic64_fetch_add_unless(). The instrumented atomics are updated to take this case into account. There should be no functional change as a result of this patch. Signed-off-by: Mark Rutland <mark.rutland@arm.com> Reviewed-by: Will Deacon <will.deacon@arm.com> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Albert Ou <albert@sifive.com> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Boqun Feng <boqun.feng@gmail.com> Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Matt Turner <mattst88@gmail.com> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Palmer Dabbelt <palmer@sifive.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Richard Henderson <rth@twiddle.net> Cc: Russell King <linux@armlinux.org.uk> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Vineet Gupta <vgupta@synopsys.com> Link: https://lore.kernel.org/lkml/20180621121321.4761-8-mark.rutland@arm.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2018-06-21 15:13:10 +03:00
/**
* atomic64_add_unless - add unless the number is already a given value
* @v: pointer of type atomic_t
* @a: the amount to add to v...
* @u: ...unless v is equal to u.
*
* Atomically adds @a to @v, if @v was not already @u.
* Returns true if the addition was done.
*/
static inline bool atomic64_add_unless(atomic64_t *v, long long a, long long u)
{
return atomic64_fetch_add_unless(v, a, u) != u;
}
/**
* atomic64_inc_not_zero - increment unless the number is zero
* @v: pointer of type atomic64_t
*
* Atomically increments @v by 1, if @v is non-zero.
* Returns true if the increment was done.
*/
#ifndef atomic64_inc_not_zero
#define atomic64_inc_not_zero(v) atomic64_add_unless((v), 1, 0)
#endif
2018-06-21 15:13:18 +03:00
/**
* atomic64_inc_and_test - increment and test
* @v: pointer of type atomic64_t
*
* Atomically increments @v by 1
* and returns true if the result is zero, or false for all
* other cases.
*/
#ifndef atomic64_inc_and_test
static inline bool atomic64_inc_and_test(atomic64_t *v)
{
return atomic64_inc_return(v) == 0;
}
#endif
/**
* atomic64_dec_and_test - decrement and test
* @v: pointer of type atomic64_t
*
* Atomically decrements @v by 1 and
* returns true if the result is 0, or false for all other
* cases.
*/
#ifndef atomic64_dec_and_test
static inline bool atomic64_dec_and_test(atomic64_t *v)
{
return atomic64_dec_return(v) == 0;
}
#endif
/**
* atomic64_sub_and_test - subtract value from variable and test result
* @i: integer value to subtract
* @v: pointer of type atomic64_t
*
* Atomically subtracts @i from @v and returns
* true if the result is zero, or false for all
* other cases.
*/
#ifndef atomic64_sub_and_test
static inline bool atomic64_sub_and_test(long long i, atomic64_t *v)
{
return atomic64_sub_return(i, v) == 0;
}
#endif
/**
* atomic64_add_negative - add and test if negative
* @i: integer value to add
* @v: pointer of type atomic64_t
*
* Atomically adds @i to @v and returns true
* if the result is negative, or false when
* result is greater than or equal to zero.
*/
#ifndef atomic64_add_negative
static inline bool atomic64_add_negative(long long i, atomic64_t *v)
{
return atomic64_add_return(i, v) < 0;
}
#endif
#ifndef atomic64_inc_unless_negative
static inline bool atomic64_inc_unless_negative(atomic64_t *v)
{
long long c = atomic64_read(v);
do {
if (unlikely(c < 0))
return false;
} while (!atomic64_try_cmpxchg(v, &c, c + 1));
return true;
}
#endif
#ifndef atomic64_dec_unless_positive
static inline bool atomic64_dec_unless_positive(atomic64_t *v)
{
long long c = atomic64_read(v);
do {
if (unlikely(c > 0))
return false;
} while (!atomic64_try_cmpxchg(v, &c, c - 1));
return true;
}
#endif
/*
* atomic64_dec_if_positive - decrement by 1 if old value positive
* @v: pointer of type atomic64_t
*
* The function returns the old value of *v minus 1, even if
* the atomic64 variable, v, was not decremented.
*/
#ifndef atomic64_dec_if_positive
static inline long long atomic64_dec_if_positive(atomic64_t *v)
{
long long dec, c = atomic64_read(v);
do {
dec = c - 1;
if (unlikely(dec < 0))
break;
} while (!atomic64_try_cmpxchg(v, &c, dec));
return dec;
}
#endif
#define atomic64_cond_read_relaxed(v, c) smp_cond_load_relaxed(&(v)->counter, (c))
#define atomic64_cond_read_acquire(v, c) smp_cond_load_acquire(&(v)->counter, (c))
#include <asm-generic/atomic-long.h>
#endif /* _LINUX_ATOMIC_H */