From 0a4ffc921c8c63dbbc2ee27eb7a18549692bf2e4 Mon Sep 17 00:00:00 2001 Message-Id: <0a4ffc921c8c63dbbc2ee27eb7a18549692bf2e4.1601675153.git.zanussi@kernel.org> In-Reply-To: <5b5a156f9808b1acf1205606e03da117214549ea.1601675151.git.zanussi@kernel.org> References: <5b5a156f9808b1acf1205606e03da117214549ea.1601675151.git.zanussi@kernel.org> From: Julien Grall Date: Wed, 21 Aug 2019 10:24:09 +0100 Subject: [PATCH 295/333] hrtimer: Prevent using hrtimer_grab_expiry_lock() on migration_base Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/4.19/older/patches-4.19.148-rt64.tar.xz [ Upstream commit cef1b87f98823af923a386f3f69149acb212d4a1 ] 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 Link: https://lkml.kernel.org/r/alpine.DEB.2.21.1908211557420.2223@nanos.tec.linutronix.de Signed-off-by: Steven Rostedt (VMware) [bigeasy: rewrite changelog] Signed-off-by: Sebastian Andrzej Siewior --- kernel/time/hrtimer.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/kernel/time/hrtimer.c b/kernel/time/hrtimer.c index 49d20fe8570f..1a5167c68310 100644 --- a/kernel/time/hrtimer.c +++ b/kernel/time/hrtimer.c @@ -943,7 +943,7 @@ void hrtimer_grab_expiry_lock(const struct hrtimer *timer) { 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); } -- 2.17.1