From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org, Julien Grall <julien.grall@arm.com>
Subject: [PATCH v2] hrtimer: Add a missing bracket and hide `migration_base' on !SMP
Date: Wed, 4 Sep 2019 16:55:27 +0200 [thread overview]
Message-ID: <20190904145527.eah7z56ntwobqm6j@linutronix.de> (raw)
In-Reply-To: <alpine.DEB.2.21.1909041633580.1902@nanos.tec.linutronix.de>
The recent change to avoid taking the expiry lock when a 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>
---
v1…v2:
- use is_migration_base() as a helper function
- slightly reword the commit message
kernel/time/hrtimer.c | 12 +++++++++++-
1 file changed, 11 insertions(+), 1 deletion(-)
diff --git a/kernel/time/hrtimer.c b/kernel/time/hrtimer.c
index f5a1a5e16216c..eaf31ac38efbb 100644
--- a/kernel/time/hrtimer.c
+++ b/kernel/time/hrtimer.c
@@ -140,6 +140,11 @@ static struct hrtimer_cpu_base migration_cpu_base = {
#define migration_base migration_cpu_base.clock_base[0]
+static bool is_migration_base(struct hrtimer_clock_base *base)
+{
+ return base == &migration_base;
+}
+
/*
* We are using hashed locking: holding per_cpu(hrtimer_bases)[n].lock
* means that all timers which are tied to this base via timer->base are
@@ -264,6 +269,11 @@ switch_hrtimer_base(struct hrtimer *timer, struct hrtimer_clock_base *base,
#else /* CONFIG_SMP */
+static bool is_migration_base(struct hrtimer_clock_base *base)
+{
+ return false;
+}
+
static inline struct hrtimer_clock_base *
lock_hrtimer_base(const struct hrtimer *timer, unsigned long *flags)
{
@@ -1221,7 +1231,7 @@ void hrtimer_cancel_wait_running(const struct hrtimer *timer)
* 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)
+ if (!timer->is_soft || is_migration_base(base)) {
cpu_relax();
return;
}
--
2.23.0
prev parent reply other threads:[~2019-09-04 14:55 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 ` [PATCH] hrtimer: Add a missing bracket and hide `migration_base' on !SMP Sebastian Andrzej Siewior
2019-09-04 14:39 ` Thomas Gleixner
2019-09-04 14:55 ` Sebastian Andrzej Siewior [this message]
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