1 files changed, 38 insertions, 0 deletions
diff --git a/debian/patches-rt/0292-hrtimer-Use-READ_ONCE-to-access-timer-base-in-hrimer.patch b/debian/patches-rt/0292-hrtimer-Use-READ_ONCE-to-access-timer-base-in-hrimer.patch
new file mode 100644
index 000000000..96b0c6320
--- /dev/null
+++ b/debian/patches-rt/0292-hrtimer-Use-READ_ONCE-to-access-timer-base-in-hrimer.patch
@@ -0,0 +1,38 @@
+From: Julien Grall <julien.grall@arm.com>
+Date: Wed, 21 Aug 2019 10:24:07 +0100
+Subject: [PATCH 292/342] hrtimer: Use READ_ONCE to access timer->base in
+ hrimer_grab_expiry_lock()
+Origin: https://git.kernel.org/cgit/linux/kernel/git/rt/linux-stable-rt.git/commit?id=651af665014e442103551831276cb17778ec5ffa
+
+[ 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);