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From: Julien Grall <julien.grall@arm.com>
Date: Wed, 21 Aug 2019 10:24:09 +0100
Subject: [PATCH 3/3] hrtimer: Prevent using hrtimer_grab_expiry_lock() on
migration_base
Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/5.2/older/patches-5.2.17-rt9.tar.xz
As tglx puts it:
|If base == migration_base then there is no point to lock soft_expiry_lock
|simply because the timer is not executing the callback in soft irq context
|and the whole lock/unlock dance can be avoided.
Furthermore, all the path leading to hrtimer_grab_expiry_lock() assumes
timer->base and timer->base->cpu_base are always non-NULL. So it is safe
to remove the NULL checks here.
Signed-off-by: Julien Grall <julien.grall@arm.com>
Link: https://lkml.kernel.org/r/alpine.DEB.2.21.1908211557420.2223@nanos.tec.linutronix.de
[bigeasy: rewrite changelog]
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
---
kernel/time/hrtimer.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/kernel/time/hrtimer.c
+++ b/kernel/time/hrtimer.c
@@ -934,7 +934,7 @@ void hrtimer_grab_expiry_lock(const stru
{
struct hrtimer_clock_base *base = READ_ONCE(timer->base);
- if (timer->is_soft && base && base->cpu_base) {
+ if (timer->is_soft && base != &migration_base) {
spin_lock(&base->cpu_base->softirq_expiry_lock);
spin_unlock(&base->cpu_base->softirq_expiry_lock);
}
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