Commit 3822da3e authored Dec 21, 2016 by Nicolai Hähnle Committed by Ingo Molnar Jan 14, 2017

locking/ww_mutex: Extract stamp comparison to __ww_mutex_stamp_after()

The function will be re-used in subsequent patches.

Signed-off-by: Nicolai Hähnle <Nicolai.Haehnle@amd.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Daniel Vetter <daniel@ffwll.ch>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Maarten Lankhorst <dev@mblankhorst.nl>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: dri-devel@lists.freedesktop.org
Link: http://lkml.kernel.org/r/1482346000-9927-4-git-send-email-nhaehnle@gmail.com

Signed-off-by: Ingo Molnar <mingo@kernel.org>

parent e274795e

kernel/locking/mutex.c

+8 −2

Original line number	Diff line number	Diff line
		@@ -281,6 +281,13 @@ static __always_inline void ww_mutex_lock_acquired(struct ww_mutex *ww,
		ww_ctx->acquired++;
		}

		static inline bool __sched
		__ww_ctx_stamp_after(struct ww_acquire_ctx a, struct ww_acquire_ctx b)
		{
		return a->stamp - b->stamp <= LONG_MAX &&
		(a->stamp != b->stamp \|\| a > b);
		}

		/*
		* After acquiring lock with fastpath or when we lost out in contested
		* slowpath, set ctx and wake up any waiters so they can recheck.
		@@ -597,8 +604,7 @@ __ww_mutex_lock_check_stamp(struct mutex lock, struct ww_acquire_ctx ctx)
		if (!hold_ctx)
		return 0;

		if (ctx->stamp - hold_ctx->stamp <= LONG_MAX &&
		(ctx->stamp != hold_ctx->stamp \|\| ctx > hold_ctx)) {
		if (__ww_ctx_stamp_after(ctx, hold_ctx)) {
		#ifdef CONFIG_DEBUG_MUTEXES
		DEBUG_LOCKS_WARN_ON(ctx->contending_lock);
		ctx->contending_lock = ww;