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From: "Nicolai Hähnle" <nhaehnle@gmail.com>
To: linux-kernel@vger.kernel.org
Cc: "Maarten Lankhorst" <dev@mblankhorst.nl>,
	"Nicolai Hähnle" <Nicolai.Haehnle@amd.com>,
	"Peter Zijlstra" <peterz@infradead.org>,
	dri-devel@lists.freedesktop.org, "Ingo Molnar" <mingo@redhat.com>
Subject: [PATCH v3 03/12] locking/ww_mutex: Extract stamp comparison to __ww_mutex_stamp_after
Date: Wed, 21 Dec 2016 19:46:31 +0100	[thread overview]
Message-ID: <1482346000-9927-4-git-send-email-nhaehnle@gmail.com> (raw)
In-Reply-To: <1482346000-9927-1-git-send-email-nhaehnle@gmail.com>

From: Nicolai Hähnle <Nicolai.Haehnle@amd.com>

The function will be re-used in subsequent patches.

v3: rename to __ww_ctx_stamp_after (Chris Wilson)

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>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
---
 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 c02c566..66718d6 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_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.
@@ -602,8 +609,7 @@ __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;
-- 
2.7.4

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  parent reply	other threads:[~2016-12-21 18:46 UTC|newest]

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <1482346000-9927-1-git-send-email-nhaehnle@gmail.com>
2016-12-21 18:46 ` [PATCH v3 01/12] drm/vgem: Use ww_mutex_(un)lock even with a NULL context Nicolai Hähnle
2016-12-21 18:46 ` [PATCH v3 02/12] locking/mutex: Fix a race with handoffs and interruptible waits Nicolai Hähnle
2016-12-21 18:46 ` Nicolai Hähnle [this message]
2016-12-22  1:58   ` [PATCH v3 03/12] locking/ww_mutex: Extract stamp comparison to __ww_mutex_stamp_after zhoucm1
2016-12-22  8:43     ` Nicolai Hähnle
2016-12-21 18:46 ` [PATCH v3 04/12] locking/ww_mutex: Set use_ww_ctx even when locking without a context Nicolai Hähnle
2016-12-21 18:46 ` [PATCH v3 05/12] locking/ww_mutex: Remove the __ww_mutex_lock inline wrappers Nicolai Hähnle
2016-12-23 10:48   ` Peter Zijlstra
2016-12-23 11:16     ` Nicolai Hähnle
2016-12-23 12:13       ` Peter Zijlstra
2016-12-21 18:46 ` [PATCH v3 06/12] locking/ww_mutex: Add waiters in stamp order Nicolai Hähnle
2016-12-21 18:46 ` [PATCH v3 07/12] locking/ww_mutex: Notify waiters that have to back off while adding tasks to wait list Nicolai Hähnle
2016-12-21 18:46 ` [PATCH v3 08/12] locking/ww_mutex: Wake at most one waiter for back off when acquiring the lock Nicolai Hähnle
2016-12-21 18:46 ` [PATCH v3 09/12] locking/ww_mutex: Re-check ww->ctx in the inner optimistic spin loop Nicolai Hähnle
2016-12-21 18:46 ` [PATCH v3 10/12] locking/ww_mutex: Yield to other waiters from optimistic spin Nicolai Hähnle
2017-01-05 17:47   ` Peter Zijlstra
2016-12-21 18:46 ` [PATCH v3 11/12] locking/mutex: Initialize mutex_waiter::ww_ctx with poison when debugging Nicolai Hähnle
2016-12-21 18:46 ` [PATCH v3 12/12] Documentation/locking/ww_mutex: Update the design document Nicolai Hähnle

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