diff options
Diffstat (limited to 'debian/patches-rt/0293-hrtimer-Use-READ_ONCE-to-access-timer-base-in-hrimer.patch')
| -rw-r--r-- | debian/patches-rt/0293-hrtimer-Use-READ_ONCE-to-access-timer-base-in-hrimer.patch | 42 |
1 files changed, 42 insertions, 0 deletions
diff --git a/debian/patches-rt/0293-hrtimer-Use-READ_ONCE-to-access-timer-base-in-hrimer.patch b/debian/patches-rt/0293-hrtimer-Use-READ_ONCE-to-access-timer-base-in-hrimer.patch new file mode 100644 index 000000000..2f06144ba --- /dev/null +++ b/debian/patches-rt/0293-hrtimer-Use-READ_ONCE-to-access-timer-base-in-hrimer.patch @@ -0,0 +1,42 @@ +From 656b33d3842f931f31f5149e458db52b85c4af3e Mon Sep 17 00:00:00 2001 +From: Julien Grall <julien.grall@arm.com> +Date: Wed, 21 Aug 2019 10:24:07 +0100 +Subject: [PATCH 293/347] hrtimer: Use READ_ONCE to access timer->base in + hrimer_grab_expiry_lock() +Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/4.19/older/patches-4.19.246-rt110.tar.xz + +[ Upstream commit 2c8fdbe7ef0ad06c1a326886c5954e117b5657d6 ] + +The update to timer->base is protected by the base->cpu_base->lock(). +However, hrtimer_grab_expirty_lock() does not access it with the lock. + +So it would theorically be possible to have timer->base changed under +our feet. We need to prevent the compiler to refetch timer->base so the +check and the access is performed on the same base. + +Other access of timer->base are either done with a lock or protected +with READ_ONCE(). So use READ_ONCE() in hrtimer_grab_expirty_lock(). + +Signed-off-by: Julien Grall <julien.grall@arm.com> +Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> +Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org> +--- + 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 eb2db7e6a241..dff440fd968b 100644 +--- a/kernel/time/hrtimer.c ++++ b/kernel/time/hrtimer.c +@@ -959,7 +959,7 @@ EXPORT_SYMBOL_GPL(hrtimer_forward); + + void hrtimer_grab_expiry_lock(const struct hrtimer *timer) + { +- struct hrtimer_clock_base *base = timer->base; ++ struct hrtimer_clock_base *base = READ_ONCE(timer->base); + + if (base && base->cpu_base) { + spin_lock(&base->cpu_base->softirq_expiry_lock); +-- +2.36.1 + |