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Commit 1460cb65 authored by Tejun Heo's avatar Tejun Heo Committed by Ingo Molnar
Browse files

locking/mutex, sched/wait: Add mutex_lock_io() 



We sometimes end up propagating IO blocking through mutexes; however,
because there currently is no way of annotating mutex sleeps as
iowait, there are cases where iowait and /proc/stat:procs_blocked
report misleading numbers obscuring the actual state of the system.

This patch adds mutex_lock_io() so that mutex sleeps can be marked as
iowait in those cases.

Signed-off-by: default avatarTejun Heo <tj@kernel.org>
Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: adilger.kernel@dilger.ca
Cc: jack@suse.com
Cc: kernel-team@fb.com
Cc: mingbo@fb.com
Cc: tytso@mit.edu
Link: http://lkml.kernel.org/r/1477673892-28940-4-git-send-email-tj@kernel.org


Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent 10ab5643

include/linux/mutex.h

+4 −0
Original line number Diff line number Diff line
@@ -156,10 +156,12 @@ extern int __must_check mutex_lock_interruptible_nested(struct mutex *lock, 
					unsigned int subclass);

extern int __must_check mutex_lock_killable_nested(struct mutex *lock,

					unsigned int subclass);

extern void mutex_lock_io_nested(struct mutex *lock, unsigned int subclass);



#define mutex_lock(lock) mutex_lock_nested(lock, 0)

#define mutex_lock_interruptible(lock) mutex_lock_interruptible_nested(lock, 0)

#define mutex_lock_killable(lock) mutex_lock_killable_nested(lock, 0)

#define mutex_lock_io(lock) mutex_lock_io_nested(lock, 0)



#define mutex_lock_nest_lock(lock, nest_lock)				\

do {									\
@@ -171,11 +173,13 @@ do { \ 
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);

extern void mutex_lock_io(struct mutex *lock);



# define mutex_lock_nested(lock, subclass) 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)

# define mutex_lock_nest_io(lock, nest_lock) mutex_io(lock)

#endif



/*

kernel/locking/mutex.c

+24 −0
Original line number Diff line number Diff line
@@ -783,6 +783,20 @@ mutex_lock_interruptible_nested(struct mutex *lock, unsigned int subclass) 
}

EXPORT_SYMBOL_GPL(mutex_lock_interruptible_nested);



void __sched

mutex_lock_io_nested(struct mutex *lock, unsigned int subclass)

{

	int token;



	might_sleep();



	token = io_schedule_prepare();

	__mutex_lock_common(lock, TASK_UNINTERRUPTIBLE,

			    subclass, NULL, _RET_IP_, NULL, 0);

	io_schedule_finish(token);

}

EXPORT_SYMBOL_GPL(mutex_lock_io_nested);



static inline int

ww_mutex_deadlock_injection(struct ww_mutex *lock, struct ww_acquire_ctx *ctx)

{
@@ -950,6 +964,16 @@ int __sched mutex_lock_killable(struct mutex *lock) 
}

EXPORT_SYMBOL(mutex_lock_killable);



void __sched mutex_lock_io(struct mutex *lock)

{

	int token;



	token = io_schedule_prepare();

	mutex_lock(lock);

	io_schedule_finish(token);

}

EXPORT_SYMBOL_GPL(mutex_lock_io);



static noinline void __sched

__mutex_lock_slowpath(struct mutex *lock)

{