Will Deacon 95bcade33a locking/qspinlock: Ensure node is initialised before updating prev->next ... When a locker ends up queuing on the qspinlock locking slowpath, we initialise the relevant mcs node and publish it indirectly by updating the tail portion of the lock word using xchg_tail. If we find that there was a pre-existing locker in the queue, we subsequently update their ->next field to point at our node so that we are notified when it's our turn to take the lock. This can be roughly illustrated as follows: /* Initialise the fields in node and encode a pointer to node in tail */ tail = initialise_node(node); /* * Exchange tail into the lockword using an atomic read-modify-write * operation with release semantics */ old = xchg_tail(lock, tail); /* If there was a pre-existing waiter ... */ if (old & _Q_TAIL_MASK) { prev = decode_tail(old); smp_read_barrier_depends(); /* ... then update their ->next field to point to node. WRITE_ONCE(prev->next, node); } The conditional update of prev->next therefore relies on the address dependency from the result of xchg_tail ensuring order against the prior initialisation of node. However, since the release semantics of the xchg_tail operation apply only to the write portion of the RmW, then this ordering is not guaranteed and it is possible for the CPU to return old before the writes to node have been published, consequently allowing us to point prev->next to an uninitialised node. This patch fixes the problem by making the update of prev->next a RELEASE operation, which also removes the reliance on dependency ordering. Signed-off-by: Will Deacon <will.deacon@arm.com> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/1518528177-19169-2-git-send-email-will.deacon@arm.com Signed-off-by: Ingo Molnar <mingo@kernel.org>		2018-02-13 14:50:14 +01:00
..
bpf	bpf: fix bpf_prog_array_copy_to_user() issues	2018-02-03 01:49:21 +01:00
cgroup	kernel/cpuset: current_cpuset_is_being_rebound can be boolean	2018-02-06 18:32:47 -08:00
configs	Makefile: introduce CONFIG_CC_STACKPROTECTOR_AUTO	2018-02-06 18:32:44 -08:00
debug	signal: Simplify and fix kdb_send_sig	2018-01-03 18:01:08 -06:00
events	Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next	2018-01-31 14:31:10 -08:00
gcov	License cleanup: add SPDX GPL-2.0 license identifier to files with no license	2017-11-02 11:10:55 +01:00
irq	genirq: remove unneeded kallsyms include	2018-02-06 18:32:47 -08:00
livepatch	Merge branch 'for-4.16/remove-immediate' into for-linus	2018-01-31 16:36:38 +01:00
locking	locking/qspinlock: Ensure node is initialised before updating prev->next	2018-02-13 14:50:14 +01:00
power	x86/power: Fix swsusp_arch_resume prototype	2018-02-02 23:33:50 +01:00
printk	Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/pmladek/printk	2018-02-01 13:36:15 -08:00
rcu	SCSI misc on 20180131	2018-01-31 11:23:28 -08:00
sched	Merge branch 'akpm' (patches from Andrew)	2018-02-06 22:15:42 -08:00
time	hrtimer: remove unneeded kallsyms include	2018-02-06 18:32:47 -08:00
trace	Mostly clean ups and small fixes	2018-02-01 13:15:23 -08:00
.gitignore	…
Kconfig.freezer	…
Kconfig.hz	…
Kconfig.locks	…
Kconfig.preempt	…
Makefile	error-injection: Support fault injection framework	2018-01-12 17:33:38 -08:00
acct.c	kernel/acct.c: fix the acct->needcheck check in check_free_space()	2018-01-04 16:45:09 -08:00
async.c	kernel/async.c: revert "async: simplify lowest_in_progress()"	2018-02-06 18:32:44 -08:00
audit.c	Audit: remove unused audit_log_secctx function	2017-11-10 16:08:47 -05:00
audit.h	audit/stable-4.15 PR 20171113	2017-11-15 13:28:48 -08:00
audit_fsnotify.c	Merge branch 'fsnotify' of git://git.kernel.org/pub/scm/linux/kernel/git/jack/linux-fs	2017-05-03 11:05:15 -07:00
audit_tree.c	Merge branch 'fsnotify' of git://git.kernel.org/pub/scm/linux/kernel/git/jack/linux-fs	2017-11-14 14:08:20 -08:00
audit_watch.c	audit/stable-4.13 PR 20170816	2017-08-16 16:48:34 -07:00
auditfilter.c	audit: filter PATH records keyed on filesystem magic	2017-11-10 16:08:56 -05:00
auditsc.c	audit/stable-4.15 PR 20171113	2017-11-15 13:28:48 -08:00
backtracetest.c	…
bounds.c	License cleanup: add SPDX GPL-2.0 license identifier to files with no license	2017-11-02 11:10:55 +01:00
capability.c	License cleanup: add SPDX GPL-2.0 license identifier to files with no license	2017-11-02 11:10:55 +01:00
compat.c	cpumask: make cpumask_size() return "unsigned int"	2018-02-06 18:32:45 -08:00
configs.c	…
context_tracking.c	…
cpu.c	Merge branch 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip	2017-12-31 12:30:34 -08:00
cpu_pm.c	PM / CPU: replace raw_notifier with atomic_notifier	2017-07-31 13:09:49 +02:00
crash_core.c	kdump: write correct address of mem_section into vmcoreinfo	2018-01-13 10:42:48 -08:00
crash_dump.c	…
cred.c	doc: ReSTify credentials.txt	2017-05-18 10:30:19 -06:00
delayacct.c	delayacct: Account blkio completion on the correct task	2018-01-16 03:29:36 +01:00
dma.c	License cleanup: add SPDX GPL-2.0 license identifier to files with no license	2017-11-02 11:10:55 +01:00
elfcore.c	License cleanup: add SPDX GPL-2.0 license identifier to files with no license	2017-11-02 11:10:55 +01:00
exec_domain.c	License cleanup: add SPDX GPL-2.0 license identifier to files with no license	2017-11-02 11:10:55 +01:00
exit.c	kernel/exit.c: export abort() to modules	2018-01-04 16:45:09 -08:00
extable.c	kprobes, x86/alternatives: Use text_mutex to protect smp_alt_modules	2017-11-07 12:20:09 +01:00
fail_function.c	error-injection: Support fault injection framework	2018-01-12 17:33:38 -08:00
fork.c	Merge branch 'akpm' (patches from Andrew)	2018-02-06 22:15:42 -08:00
freezer.c	…
futex.c	pids: introduce find_get_task_by_vpid() helper	2018-02-06 18:32:46 -08:00
futex_compat.c	License cleanup: add SPDX GPL-2.0 license identifier to files with no license	2017-11-02 11:10:55 +01:00
groups.c	kernel: make groups_sort calling a responsibility group_info allocators	2017-12-14 16:00:49 -08:00
hung_task.c	kernel/hung_task.c: defer showing held locks	2017-05-08 17:15:10 -07:00
irq_work.c	irq/work: Improve the flag definitions	2018-01-08 19:43:15 +01:00
jump_label.c	sched/core: Fix cpu.max vs. cpuhotplug deadlock	2018-01-24 10:03:44 +01:00
kallsyms.c	Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/pmladek/printk	2018-02-01 13:36:15 -08:00
kcmp.c	License cleanup: add SPDX GPL-2.0 license identifier to files with no license	2017-11-02 11:10:55 +01:00
kcov.c	kcov: detect double association with a single task	2018-02-06 18:32:46 -08:00
kexec.c	kdump: protect vmcoreinfo data under the crash memory	2017-07-12 16:26:00 -07:00
kexec_core.c	x86/mm, kexec: Allow kexec to be used with SME	2017-07-18 11:38:04 +02:00
kexec_file.c	resource: Provide resource struct in resource walk callback	2017-11-07 15:35:57 +01:00
kexec_internal.h	License cleanup: add SPDX GPL-2.0 license identifier to files with no license	2017-11-02 11:10:55 +01:00
kmod.c	kmod: move #ifdef CONFIG_MODULES wrapper to Makefile	2017-09-08 18:26:51 -07:00
kprobes.c	error-injection: Separate error-injection from kprobe	2018-01-12 17:33:38 -08:00
ksysfs.c	kexec: move vmcoreinfo out of the kernel's .bss section	2017-07-12 16:25:59 -07:00
kthread.c	treewide: Remove TIMER_FUNC_TYPE and TIMER_DATA_TYPE casts	2017-11-21 16:35:54 -08:00
latencytop.c	sched/headers: Prepare to move sched_info_on() and force_schedstat_enabled() from <linux/sched.h> to <linux/sched/stat.h>	2017-03-02 08:42:39 +01:00
memremap.c	mm: Fix devm_memremap_pages() collision handling	2018-01-19 16:29:56 -08:00
module-internal.h	…
module.c	Modules updates for v4.16	2018-02-07 14:29:34 -08:00
module_signing.c	…
notifier.c	kernel/notifier.c: simplify expression	2017-02-24 17:46:56 -08:00
nsproxy.c	perf: Add PERF_RECORD_NAMESPACES to include namespaces related info	2017-03-13 15:57:41 -03:00
padata.c	padata: add SPDX identifier	2018-01-05 18:43:00 +11:00
panic.c	kernel/panic.c: add TAINT_AUX	2017-11-17 16:10:04 -08:00
params.c	kernel/params.c: improve STANDARD_PARAM_DEF readability	2017-10-03 17:54:26 -07:00
pid.c	pids: introduce find_get_task_by_vpid() helper	2018-02-06 18:32:46 -08:00
pid_namespace.c	pid: remove pidhash	2017-11-17 16:10:04 -08:00
profile.c	sched/headers: Prepare to move sched_info_on() and force_schedstat_enabled() from <linux/sched.h> to <linux/sched/stat.h>	2017-03-02 08:42:39 +01:00
ptrace.c	pids: introduce find_get_task_by_vpid() helper	2018-02-06 18:32:46 -08:00
range.c	License cleanup: add SPDX GPL-2.0 license identifier to files with no license	2017-11-02 11:10:55 +01:00
reboot.c	kernel/reboot.c: add devm_register_reboot_notifier()	2017-11-17 16:10:04 -08:00
relay.c	kernel/relay.c: revert "kernel/relay.c: fix potential memory leak"	2018-02-06 18:32:46 -08:00
resource.c	Merge branch 'akpm' (patches from Andrew)	2018-02-06 22:15:42 -08:00
seccomp.c	Merge branch 'next-seccomp' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security	2018-01-31 13:44:45 -08:00
signal.c	Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/livepatching	2018-01-31 13:02:18 -08:00
smp.c	smp/core: Use lockdep to assert IRQs are disabled/enabled	2017-11-08 11:13:50 +01:00
smpboot.c	watchdog/core, powerpc: Lock cpus across reconfiguration	2017-10-04 10:53:54 +02:00
smpboot.h	License cleanup: add SPDX GPL-2.0 license identifier to files with no license	2017-11-02 11:10:55 +01:00
softirq.c	softirq: Eliminate cond_resched_rcu_qs() in favor of cond_resched()	2017-12-04 10:28:58 -08:00
stacktrace.c	stacktrace/x86: add function for detecting reliable stack traces	2017-03-08 09:18:02 +01:00
stop_machine.c	stop_machine: Provide stop_machine_cpuslocked()	2017-05-26 10:10:36 +02:00
sys.c	fix typo in assignment of fs default overflow gid	2017-12-14 16:01:45 -06:00
sys_ni.c	License cleanup: add SPDX GPL-2.0 license identifier to files with no license	2017-11-02 11:10:55 +01:00
sysctl.c	pipe: reject F_SETPIPE_SZ with size over UINT_MAX	2018-02-06 18:32:47 -08:00
sysctl_binary.c	License cleanup: add SPDX GPL-2.0 license identifier to files with no license	2017-11-02 11:10:55 +01:00
task_work.c	locking/barriers: Convert users of lockless_dereference() to READ_ONCE()	2017-12-17 13:57:15 +01:00
taskstats.c	pids: introduce find_get_task_by_vpid() helper	2018-02-06 18:32:46 -08:00
test_kprobes.c	kprobes: Disable the jprobes test code	2017-10-20 11:02:54 +02:00
torture.c	torture: Save a line in stutter_wait(): while -> for	2017-12-11 09:18:30 -08:00
tracepoint.c	tracepoint: Remove smp_read_barrier_depends() from comment	2017-12-04 10:52:56 -08:00
tsacct.c	sched/headers: Prepare to move cputime functionality from <linux/sched.h> into <linux/sched/cputime.h>	2017-03-02 08:42:39 +01:00
ucount.c	ucount: Remove the atomicity from ucount->count	2017-03-06 15:26:37 -06:00
uid16.c	kernel: make groups_sort calling a responsibility group_info allocators	2017-12-14 16:00:49 -08:00
umh.c	kernel/umh.c: optimize 'proc_cap_handler()'	2017-11-17 16:10:01 -08:00
up.c	smp: Avoid using two cache lines for struct call_single_data	2017-08-29 15:14:38 +02:00
user-return-notifier.c	…
user.c	userns: use union in {g,u}idmap struct	2017-10-31 17:22:58 -05:00
user_namespace.c	Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace	2017-11-16 12:20:15 -08:00
utsname.c	sched/headers: Prepare to move the task_lock()/unlock() APIs to <linux/sched/task.h>	2017-03-02 08:42:38 +01:00
utsname_sysctl.c	sched/headers: Remove <linux/rwsem.h> from <linux/sched.h>	2017-03-03 01:45:36 +01:00
watchdog.c	Merge branch 'linus' into sched/core, to pick up fixes	2017-11-08 10:17:15 +01:00
watchdog_hld.c	Merge branch 'linus' into core/urgent, to pick up dependent commits	2017-11-04 08:53:04 +01:00
workqueue.c	Staging/IIO patches for 4.16-rc1	2018-02-01 09:51:57 -08:00
workqueue_internal.h	Merge branch 'for-4.14-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq	2017-11-06 12:26:49 -08:00