From: Peter Zijlstra <peterz@infradead.org>
To: Ingo Molnar <mingo@kernel.org>
Cc: Oleg Nesterov <oleg@redhat.com>,
Paul McKenney <paulmck@linux.vnet.ibm.com>,
Linus Torvalds <torvalds@linux-foundation.org>,
Thomas Gleixner <tglx@linutronix.de>,
Andrew Morton <akpm@linux-foundation.org>,
linux-kernel@vger.kernel.org,
Peter Zijlstra <peterz@infradead.org>
Subject: [PATCH 2/6] sched, wait: Change timeout logic
Date: Mon, 30 Sep 2013 17:22:44 +0200 [thread overview]
Message-ID: <20130930152624.809243897@infradead.org> (raw)
In-Reply-To: <20130930152242.207382649@infradead.org>
[-- Attachment #1: peterz-wait-change-sched-timo.patch --]
[-- Type: text/plain, Size: 2498 bytes --]
Commit 4c663cf ("wait: fix false timeouts when using
wait_event_timeout()") introduced an additional condition check after
a timeout but there's a few issues;
- it forgot one site
- it put the check after the main loop; not at the actual timeout
check.
Cure both; by wrapping the condition (as suggested by Oleg), this
avoids double evaluation of 'condition' which could be quite big.
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
---
include/linux/wait.h | 24 +++++++++++-------------
1 file changed, 11 insertions(+), 13 deletions(-)
--- a/include/linux/wait.h
+++ b/include/linux/wait.h
@@ -179,6 +179,14 @@ wait_queue_head_t *bit_waitqueue(void *,
#define wake_up_interruptible_sync_poll(x, m) \
__wake_up_sync_key((x), TASK_INTERRUPTIBLE, 1, (void *) (m))
+#define ___wait_cond_timeout(condition, ret) \
+({ \
+ bool __cond = (condition); \
+ if (__cond && !ret) \
+ ret = 1; \
+ __cond || !ret; \
+})
+
#define __wait_event(wq, condition) \
do { \
DEFINE_WAIT(__wait); \
@@ -217,14 +225,10 @@ do { \
\
for (;;) { \
prepare_to_wait(&wq, &__wait, TASK_UNINTERRUPTIBLE); \
- if (condition) \
+ if (___wait_cond_timeout(condition, ret)) \
break; \
ret = schedule_timeout(ret); \
- if (!ret) \
- break; \
} \
- if (!ret && (condition)) \
- ret = 1; \
finish_wait(&wq, &__wait); \
} while (0)
@@ -299,18 +303,14 @@ do { \
\
for (;;) { \
prepare_to_wait(&wq, &__wait, TASK_INTERRUPTIBLE); \
- if (condition) \
+ if (___wait_cond_timeout(condition, ret)) \
break; \
if (signal_pending(current)) { \
ret = -ERESTARTSYS; \
break; \
} \
ret = schedule_timeout(ret); \
- if (!ret) \
- break; \
} \
- if (!ret && (condition)) \
- ret = 1; \
finish_wait(&wq, &__wait); \
} while (0)
@@ -815,7 +815,7 @@ do { \
\
for (;;) { \
prepare_to_wait(&wq, &__wait, TASK_INTERRUPTIBLE); \
- if (condition) \
+ if (___wait_cond_timeout(condition, ret)) \
break; \
if (signal_pending(current)) { \
ret = -ERESTARTSYS; \
@@ -824,8 +824,6 @@ do { \
spin_unlock_irq(&lock); \
ret = schedule_timeout(ret); \
spin_lock_irq(&lock); \
- if (!ret) \
- break; \
} \
finish_wait(&wq, &__wait); \
} while (0)
next prev parent reply other threads:[~2013-09-30 15:33 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-09-30 15:22 [PATCH 0/6] sched, wait: Collapse __wait_event macros -v4 Peter Zijlstra
2013-09-30 15:22 ` [PATCH 1/6] sched, wait: Make the signal_pending() checks consistent Peter Zijlstra
2013-09-30 15:22 ` Peter Zijlstra [this message]
2013-09-30 15:48 ` [PATCH 2/6] sched, wait: Change timeout logic Linus Torvalds
2013-09-30 16:09 ` Peter Zijlstra
2013-09-30 15:22 ` [PATCH 3/6] sched, wait: Change the wait_exclusive control flow Peter Zijlstra
2013-09-30 15:22 ` [PATCH 4/6] sched, wait: Collapse __wait_event macros Peter Zijlstra
2013-09-30 15:22 ` [PATCH 5/6] sched, wait: Also use ___wait_event() for __wait_event_hrtimeout Peter Zijlstra
2013-09-30 15:22 ` [PATCH 6/6] sched, wait: Make the __wait_event*() interface more friendly Peter Zijlstra
2013-10-01 6:39 ` Ingo Molnar
2013-09-30 15:50 ` [PATCH 0/6] sched, wait: Collapse __wait_event macros -v4 Linus Torvalds
2013-09-30 16:11 ` Peter Zijlstra
2013-09-30 17:40 ` Oleg Nesterov
2013-09-30 18:00 ` Oleg Nesterov
2013-09-30 18:09 ` Peter Zijlstra
2013-09-30 18:13 ` Oleg Nesterov
2013-10-01 14:09 ` Oleg Nesterov
2013-10-01 14:39 ` Peter Zijlstra
2013-10-01 15:16 ` Oleg Nesterov
2013-10-01 17:01 ` [RFC] introduce prepare_to_wait_event() Oleg Nesterov
2013-10-01 17:25 ` Peter Zijlstra
2013-10-01 17:33 ` Oleg Nesterov
2013-10-01 17:44 ` Peter Zijlstra
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