From 1460cb65a10f6c7a6e3a1c76513338861a0a43b6 Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Fri, 28 Oct 2016 12:58:11 -0400 Subject: [PATCH] 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: Tejun Heo Signed-off-by: Peter Zijlstra (Intel) Cc: Andrew Morton Cc: Jens Axboe Cc: Linus Torvalds Cc: Mike Galbraith Cc: Peter Zijlstra Cc: Thomas Gleixner 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: Ingo Molnar --- include/linux/mutex.h | 4 ++++ kernel/locking/mutex.c | 24 ++++++++++++++++++++++++ 2 files changed, 28 insertions(+) diff --git a/include/linux/mutex.h b/include/linux/mutex.h index b97870f2debd..980ba16b8749 100644 --- a/include/linux/mutex.h +++ b/include/linux/mutex.h @@ -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 /* diff --git a/kernel/locking/mutex.c b/kernel/locking/mutex.c index 9b349619f431..8464a5cbab97 100644 --- a/kernel/locking/mutex.c +++ b/kernel/locking/mutex.c @@ -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) { -- 2.20.1