From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
To: linux-kernel@vger.kernel.org
Cc: Thomas Gleixner <tglx@linutronix.de>,
Julien Grall <julien.grall@arm.com>
Subject: [PATCH] hrtimer: Add a missing bracket and hide `migration_base' on !SMP
Date: Wed, 4 Sep 2019 16:15:40 +0200 [thread overview]
Message-ID: <20190904141540.xucehzbndjmgkrio@linutronix.de> (raw)
In-Reply-To: <156652633520.11649.15892124550118329976.tip-bot2@tip-bot2>
Commit
68b2c8c1e4210 ("hrtimer: Don't take expiry_lock when timer is currently migrated")
missed to add a bracket at the end of the if statement leading to
compile errors.
Since that commit the variable `migration_base' is always used but only
available on SMP configuration thus leading to another compile error.
The changelog says
"The timer base and base->cpu_base cannot be NULL in the code path"
so it is safe to limit this check to SMP configurations only.
Add the missing bracket to the if statement and hide `migration_base'
behind CONFIG_SMP bars.
Fixes: 68b2c8c1e4210 ("hrtimer: Don't take expiry_lock when timer is currently migrated")
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
---
kernel/time/hrtimer.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/kernel/time/hrtimer.c b/kernel/time/hrtimer.c
index f5a1a5e16216c..bc84c74ae5b96 100644
--- a/kernel/time/hrtimer.c
+++ b/kernel/time/hrtimer.c
@@ -1216,12 +1216,16 @@ void hrtimer_cancel_wait_running(const struct hrtimer *timer)
{
/* Lockless read. Prevent the compiler from reloading it below */
struct hrtimer_clock_base *base = READ_ONCE(timer->base);
+ bool is_migration_base = false;
/*
* Just relax if the timer expires in hard interrupt context or if
* it is currently on the migration base.
*/
- if (!timer->is_soft || base == &migration_base)
+#ifdef CONFIG_SMP
+ is_migration_base = base == &migration_base;
+#endif
+ if (timer->is_soft || is_migration_base) {
cpu_relax();
return;
}
--
2.23.0
next prev parent reply other threads:[~2019-09-04 14:15 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-21 9:24 [RT PATCH 0/3] hrtimer: RT fixes for hrtimer_grab_expiry_lock() Julien Grall
2019-08-21 9:24 ` [RT PATCH 1/3] hrtimer: Use READ_ONCE to access timer->base in hrimer_grab_expiry_lock() Julien Grall
2019-08-21 13:44 ` Sebastian Andrzej Siewior
2019-08-21 13:50 ` Thomas Gleixner
2019-08-21 13:59 ` Sebastian Andrzej Siewior
2019-09-26 21:47 ` Eric Dumazet
2019-08-23 2:12 ` [tip: timers/core] hrtimer: Protect lockless access to timer->base tip-bot2 for Julien Grall
2019-08-21 9:24 ` [RT PATCH 2/3] hrtimer: Don't grab the expiry lock for non-soft hrtimer Julien Grall
2019-08-21 13:49 ` Sebastian Andrzej Siewior
2019-08-21 9:24 ` [RT PATCH 3/3] hrtimer: Prevent using uninitialized spin_lock in hrtimer_grab_expiry_lock() Julien Grall
2019-08-21 14:02 ` Thomas Gleixner
2019-08-22 10:59 ` Julien Grall
2019-08-23 2:12 ` [tip: timers/core] hrtimer: Don't take expiry_lock when timer is currently migrated tip-bot2 for Julien Grall
2019-09-04 14:15 ` Sebastian Andrzej Siewior [this message]
2019-09-04 14:39 ` [PATCH] hrtimer: Add a missing bracket and hide `migration_base' on !SMP Thomas Gleixner
2019-09-04 14:55 ` [PATCH v2] " Sebastian Andrzej Siewior
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