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Lv Zheng 7e3fd81371 ACPI / debugger: Fix regression introduced by IS_ERR_VALUE() removal
The FIFO unlocking mechanism in acpi_dbg has been broken by the
following commit:

  Commit: 287980e49f
  Subject: remove lots of IS_ERR_VALUE abuses

It converted !IS_ERR_VALUE(ret) into !ret which was not entirely
correct. Fix the regression by taking ret > 0 into account too as
appropriate.

Fixes: 287980e49f (remove lots of IS_ERR_VALUE abuses)
Signed-off-by: Lv Zheng <lv.zheng@intel.com>
[ rjw: Simplifications, changelog & subject massage ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2016-07-05 23:02:34 +02:00
Arnd Bergmann 287980e49f remove lots of IS_ERR_VALUE abuses
Most users of IS_ERR_VALUE() in the kernel are wrong, as they
pass an 'int' into a function that takes an 'unsigned long'
argument. This happens to work because the type is sign-extended
on 64-bit architectures before it gets converted into an
unsigned type.

However, anything that passes an 'unsigned short' or 'unsigned int'
argument into IS_ERR_VALUE() is guaranteed to be broken, as are
8-bit integers and types that are wider than 'unsigned long'.

Andrzej Hajda has already fixed a lot of the worst abusers that
were causing actual bugs, but it would be nice to prevent any
users that are not passing 'unsigned long' arguments.

This patch changes all users of IS_ERR_VALUE() that I could find
on 32-bit ARM randconfig builds and x86 allmodconfig. For the
moment, this doesn't change the definition of IS_ERR_VALUE()
because there are probably still architecture specific users
elsewhere.

Almost all the warnings I got are for files that are better off
using 'if (err)' or 'if (err < 0)'.
The only legitimate user I could find that we get a warning for
is the (32-bit only) freescale fman driver, so I did not remove
the IS_ERR_VALUE() there but changed the type to 'unsigned long'.
For 9pfs, I just worked around one user whose calling conventions
are so obscure that I did not dare change the behavior.

I was using this definition for testing:

 #define IS_ERR_VALUE(x) ((unsigned long*)NULL == (typeof (x)*)NULL && \
       unlikely((unsigned long long)(x) >= (unsigned long long)(typeof(x))-MAX_ERRNO))

which ends up making all 16-bit or wider types work correctly with
the most plausible interpretation of what IS_ERR_VALUE() was supposed
to return according to its users, but also causes a compile-time
warning for any users that do not pass an 'unsigned long' argument.

I suggested this approach earlier this year, but back then we ended
up deciding to just fix the users that are obviously broken. After
the initial warning that caused me to get involved in the discussion
(fs/gfs2/dir.c) showed up again in the mainline kernel, Linus
asked me to send the whole thing again.

[ Updated the 9p parts as per Al Viro  - Linus ]

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Cc: Andrzej Hajda <a.hajda@samsung.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Link: https://lkml.org/lkml/2016/1/7/363
Link: https://lkml.org/lkml/2016/5/27/486
Acked-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org> # For nvmem part
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-05-27 15:26:11 -07:00
Lv Zheng 59adb3988e ACPI / debugger: Fix a redundant mutex unlock issue in acpi_aml_open()
Fix a double mutex_unlock() issue where acpi_initialize_debugger() is
called with the mutex already unlocked.

Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Lv Zheng <lv.zheng@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2015-12-28 01:29:41 +01:00
Dan Carpenter ec74765d9f ACPI / debugger: copy_to_user doesn't return errors
The copy_to/from_user() functions don't return error codes, they return
the number of bytes remaining.  We had intended to return -EFUALT here.
We actually have already checked access_ok() in an earlier function so
I don't think these functions will fail but let's fix it anyway.

Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2015-12-28 01:29:41 +01:00
Dan Carpenter 436db5ce0d ACPI / debugger: remove some unneeded conditions
"count" is unsigned so checking for less than zero here causes a static
checker warning.  And really it's better to let the access_ok() check
fail if the user passes in a NULL "buf" pointer because -EFAULT is the
correct error code.

Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2015-12-28 01:29:40 +01:00
Lv Zheng 73af2d590a ACPI / debugger: Fix an issue a flag is modified without locking
There is one line of code, executed out of locking due to rebase mistakes.
This patch fixes this issue.

Signed-off-by: Lv Zheng <lv.zheng@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2015-12-28 01:29:40 +01:00
Lv Zheng 836d083018 ACPI / debugger: Add module support for ACPI debugger
This patch converts AML debugger into a loadable module.

Note that, it implements driver unloading at the level dependent on the
module reference count. Which means if ACPI debugger is being used by a
userspace program, "rmmod acpi_dbg" should result in failure.

Signed-off-by: Lv Zheng <lv.zheng@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2015-12-15 00:17:44 +01:00
Lv Zheng 8cfb0cdf07 ACPI / debugger: Add IO interface to access debugger functionalities
This patch adds /sys/kernel/debug/acpi/acpidbg, which can be used by
userspace programs to access ACPICA debugger functionalities.

Known issue:
1. IO flush support
   acpi_os_notify_command_complete() and acpi_os_wait_command_ready() can
   be used by acpi_dbg module to implement .flush() filesystem operation.
   While this patch doesn't go that far. It then becomes userspace tool's
   duty now to flush old commands before executing new batch mode commands.

Signed-off-by: Lv Zheng <lv.zheng@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2015-12-15 00:17:44 +01:00