Messages in this thread Patch in this message | | | From | Arnd Bergmann <> | Subject | [PATCH] mutex: make mutex_lock_nested an inline function | Date | Tue, 13 Oct 2015 22:30:08 +0200 |
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The second argument of the mutex_lock_nested() helper is only evaluated if CONFIG_DEBUG_LOCK_ALLOC is set. Otherwise we get this build warning for the new regulator_lock_supply function:
drivers/regulator/core.c: In function 'regulator_lock_supply': drivers/regulator/core.c:142:6: warning: unused variable 'i' [-Wunused-variable]
To avoid the warning, this patch changes the definition of mutex_lock_nested() to be static inline function rather than a macro, which tells gcc that the variable is potentially used.
Signed-off-by: Arnd Bergmann <arnd@arndb.de> Fixes: 9f01cd4a915 ("regulator: core: introduce function to lock regulators and its supplies") --- Second try, this time fixing the root of the problem rather than the code that triggered it, as suggested by Mark Brown.
I guess this means the fix should now probably go through Ingo's sched-locking branch or through Andrew's mm patches. The warning currently only shows up in Linux-next because of Mark's regulator branch that is destined for 4.4, so it's not needed for 4.3 but also harmless.
diff --git a/include/linux/mutex.h b/include/linux/mutex.h index 2cb7531e7d7a..9494dafd7a9c 100644 --- a/include/linux/mutex.h +++ b/include/linux/mutex.h @@ -158,7 +158,10 @@ extern void mutex_lock(struct mutex *lock); extern int __must_check mutex_lock_interruptible(struct mutex *lock); extern int __must_check mutex_lock_killable(struct mutex *lock); -# define mutex_lock_nested(lock, subclass) mutex_lock(lock) +static inline void mutex_lock_nested(struct mutex *lock, unsigned int subclass) +{ + return mutex_lock(lock); +} # define mutex_lock_interruptible_nested(lock, subclass) mutex_lock_interruptible(lock) # define mutex_lock_killable_nested(lock, subclass) mutex_lock_killable(lock) # define mutex_lock_nest_lock(lock, nest_lock) mutex_lock(lock)
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