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Commit 4bd19084 authored by Davidlohr Bueso's avatar Davidlohr Bueso Committed by Ingo Molnar
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locking/mutex: Introduce ww_mutex_set_context_slowpath() 



... which is equivalent to the fastpath counter part.
This mainly allows getting some WW specific code out
of generic mutex paths.

Signed-off-by: default avatarDavidlohr Bueso <dbueso@suse.de>
Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/1420573509-24774-4-git-send-email-dave@stgolabs.net


Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent e42f678a

kernel/locking/mutex.c

+26 −18
Original line number Diff line number Diff line
@@ -147,7 +147,7 @@ static __always_inline void ww_mutex_lock_acquired(struct ww_mutex *ww, 
}



/*

 * after acquiring lock with fastpath or when we lost out in contested

 * After acquiring lock with fastpath or when we lost out in contested

 * slowpath, set ctx and wake up any waiters so they can recheck.

 *

 * This function is never called when CONFIG_DEBUG_LOCK_ALLOC is set,
@@ -191,6 +191,30 @@ ww_mutex_set_context_fastpath(struct ww_mutex *lock, 
	spin_unlock_mutex(&lock->base.wait_lock, flags);

}



/*

 * After acquiring lock in the slowpath set ctx and wake up any

 * waiters so they can recheck.

 *

 * Callers must hold the mutex wait_lock.

 */

static __always_inline void

ww_mutex_set_context_slowpath(struct ww_mutex *lock,

			      struct ww_acquire_ctx *ctx)

{

	struct mutex_waiter *cur;



	ww_mutex_lock_acquired(lock, ctx);

	lock->ctx = ctx;



	/*

	 * Give any possible sleeping processes the chance to wake up,

	 * so they can recheck if they have to back off.

	 */

	list_for_each_entry(cur, &lock->base.wait_list, list) {

		debug_mutex_wake_waiter(&lock->base, cur);

		wake_up_process(cur->task);

	}

}



#ifdef CONFIG_MUTEX_SPIN_ON_OWNER

static inline bool owner_running(struct mutex *lock, struct task_struct *owner)
@@ -576,23 +600,7 @@ __mutex_lock_common(struct mutex *lock, long state, unsigned int subclass, 


	if (use_ww_ctx) {

		struct ww_mutex *ww = container_of(lock, struct ww_mutex, base);

		struct mutex_waiter *cur;



		/*

		 * This branch gets optimized out for the common case,

		 * and is only important for ww_mutex_lock.

		 */

		ww_mutex_lock_acquired(ww, ww_ctx);

		ww->ctx = ww_ctx;



		/*

		 * Give any possible sleeping processes the chance to wake up,

		 * so they can recheck if they have to back off.

		 */

		list_for_each_entry(cur, &lock->wait_list, list) {

			debug_mutex_wake_waiter(lock, cur);

			wake_up_process(cur->task);

		}

		ww_mutex_set_context_slowpath(ww, ww_ctx);

	}



	spin_unlock_mutex(&lock->wait_lock, flags);