From: tip-bot for Thomas Gleixner <tipbot@zytor.com>
To: linux-tip-commits@vger.kernel.org
Cc: anna-maria@linutronix.de, mingo@kernel.org, tglx@linutronix.de,
linux-kernel@vger.kernel.org, hpa@zytor.com,
peterz@infradead.org
Subject: [tip:timers/core] posix-timers: Rework cancel retry loops
Date: Thu, 1 Aug 2019 12:09:11 -0700 [thread overview]
Message-ID: <tip-6945e5c2abe008302b20266248d6de95575311a8@git.kernel.org> (raw)
In-Reply-To: <20190730223828.874901027@linutronix.de>
Commit-ID: 6945e5c2abe008302b20266248d6de95575311a8
Gitweb: https://git.kernel.org/tip/6945e5c2abe008302b20266248d6de95575311a8
Author: Thomas Gleixner <tglx@linutronix.de>
AuthorDate: Wed, 31 Jul 2019 00:33:53 +0200
Committer: Thomas Gleixner <tglx@linutronix.de>
CommitDate: Thu, 1 Aug 2019 20:51:24 +0200
posix-timers: Rework cancel retry loops
As a preparatory step for adding the PREEMPT RT specific synchronization
mechanism to wait for a running timer callback, rework the timer cancel
retry loops so they call a common function. This allows trivial
substitution in one place.
Originally-by: Anna-Maria Gleixner <anna-maria@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20190730223828.874901027@linutronix.de
---
kernel/time/posix-timers.c | 29 +++++++++++++++++++++++------
1 file changed, 23 insertions(+), 6 deletions(-)
diff --git a/kernel/time/posix-timers.c b/kernel/time/posix-timers.c
index f5aedd2f60df..bbe8f9686a70 100644
--- a/kernel/time/posix-timers.c
+++ b/kernel/time/posix-timers.c
@@ -805,6 +805,17 @@ static int common_hrtimer_try_to_cancel(struct k_itimer *timr)
return hrtimer_try_to_cancel(&timr->it.real.timer);
}
+static struct k_itimer *timer_wait_running(struct k_itimer *timer,
+ unsigned long *flags)
+{
+ timer_t timer_id = READ_ONCE(timer->it_id);
+
+ unlock_timer(timer, *flags);
+ cpu_relax();
+ /* Relock the timer. It might be not longer hashed. */
+ return lock_timer(timer_id, flags);
+}
+
/* Set a POSIX.1b interval timer. */
int common_timer_set(struct k_itimer *timr, int flags,
struct itimerspec64 *new_setting,
@@ -859,8 +870,9 @@ static int do_timer_settime(timer_t timer_id, int tmr_flags,
if (old_spec64)
memset(old_spec64, 0, sizeof(*old_spec64));
-retry:
+
timr = lock_timer(timer_id, &flags);
+retry:
if (!timr)
return -EINVAL;
@@ -870,11 +882,14 @@ retry:
else
error = kc->timer_set(timr, tmr_flags, new_spec64, old_spec64);
- unlock_timer(timr, flags);
if (error == TIMER_RETRY) {
- old_spec64 = NULL; // We already got the old time...
+ // We already got the old time...
+ old_spec64 = NULL;
+ /* Unlocks and relocks the timer if it still exists */
+ timr = timer_wait_running(timr, &flags);
goto retry;
}
+ unlock_timer(timr, flags);
return error;
}
@@ -951,13 +966,15 @@ SYSCALL_DEFINE1(timer_delete, timer_t, timer_id)
struct k_itimer *timer;
unsigned long flags;
-retry_delete:
timer = lock_timer(timer_id, &flags);
+
+retry_delete:
if (!timer)
return -EINVAL;
- if (timer_delete_hook(timer) == TIMER_RETRY) {
- unlock_timer(timer, flags);
+ if (unlikely(timer_delete_hook(timer) == TIMER_RETRY)) {
+ /* Unlocks and relocks the timer if it still exists */
+ timer = timer_wait_running(timer, &flags);
goto retry_delete;
}
next prev parent reply other threads:[~2019-08-01 19:09 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-07-30 22:33 [patch 0/7] posix-timers: Prepare for PREEMPT_RT - part 1 Thomas Gleixner
2019-07-30 22:33 ` [patch 1/7] alarmtimer: Prepare for PREEMPT_RT Thomas Gleixner
2019-08-01 16:04 ` [tip:timers/core] " tip-bot for Anna-Maria Gleixner
2019-08-01 19:06 ` tip-bot for Anna-Maria Gleixner
2019-07-30 22:33 ` [patch 2/7] timerfd: " Thomas Gleixner
2019-08-01 16:04 ` [tip:timers/core] " tip-bot for Anna-Maria Gleixner
2019-08-01 19:07 ` tip-bot for Anna-Maria Gleixner
2019-07-30 22:33 ` [patch 3/7] itimers: " Thomas Gleixner
2019-08-01 16:05 ` [tip:timers/core] " tip-bot for Anna-Maria Gleixner
2019-08-01 19:07 ` tip-bot for Anna-Maria Gleixner
2019-07-30 22:33 ` [patch 4/7] posix-timers: Cleanup the flag/flags confusion Thomas Gleixner
2019-08-01 16:06 ` [tip:timers/core] " tip-bot for Anna-Maria Gleixner
2019-08-01 19:08 ` tip-bot for Thomas Gleixner
2019-07-30 22:33 ` [patch 5/7] posix-timers: Rework cancel retry loops Thomas Gleixner
2019-08-01 16:07 ` [tip:timers/core] " tip-bot for Thomas Gleixner
2019-08-01 19:09 ` tip-bot for Thomas Gleixner [this message]
2019-07-30 22:33 ` [patch 6/7] posix-timers: Move rcu_head out of it union Thomas Gleixner
2019-08-01 16:08 ` [tip:timers/core] " tip-bot for Sebastian Andrzej Siewior
2019-08-01 19:09 ` tip-bot for Sebastian Andrzej Siewior
2019-07-30 22:33 ` [patch 7/7] posix-timers: Prepare for PREEMPT_RT Thomas Gleixner
2019-07-31 9:49 ` Peter Zijlstra
2019-07-31 11:03 ` Thomas Gleixner
2019-08-01 16:08 ` [tip:timers/core] " tip-bot for Thomas Gleixner
2019-08-01 19:10 ` tip-bot for Thomas Gleixner
2019-07-31 9:49 ` [patch 0/7] posix-timers: Prepare for PREEMPT_RT - part 1 Peter Zijlstra
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