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Subject[PATCH 03/11] locking/ww_mutex: Extract stamp comparison to __ww_mutex_stamp_after
Date
From: Nicolai Hähnle <Nicolai.Haehnle@amd.com>

The function will be re-used in subsequent patches.

Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Maarten Lankhorst <dev@mblankhorst.nl>
Cc: Daniel Vetter <daniel@ffwll.ch>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: dri-devel@lists.freedesktop.org
Signed-off-by: Nicolai Hähnle <Nicolai.Haehnle@amd.com>
---
kernel/locking/mutex.c | 10 ++++++++--
1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/kernel/locking/mutex.c b/kernel/locking/mutex.c
index 0afa998..200629a 100644
--- a/kernel/locking/mutex.c
+++ b/kernel/locking/mutex.c
@@ -277,6 +277,13 @@ static __always_inline void ww_mutex_lock_acquired(struct ww_mutex *ww,
ww_ctx->acquired++;
}

+static inline bool __sched
+__ww_mutex_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.
@@ -610,8 +617,7 @@ __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_mutex_stamp_after(ctx, hold_ctx)) {
#ifdef CONFIG_DEBUG_MUTEXES
DEBUG_LOCKS_WARN_ON(ctx->contending_lock);
ctx->contending_lock = ww;
--
2.7.4
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