50 lines
1.5 KiB
Diff
50 lines
1.5 KiB
Diff
From: Tiejun Chen <tiejun.chen@windriver.com>
|
|
Date: Wed, 18 Dec 2013 17:51:49 +0800
|
|
Subject: rcutree/rcu_bh_qs: Disable irq while calling rcu_preempt_qs()
|
|
Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/4.9/older/patches-4.9-rt1.tar.xz
|
|
|
|
Any callers to the function rcu_preempt_qs() must disable irqs in
|
|
order to protect the assignment to ->rcu_read_unlock_special. In
|
|
RT case, rcu_bh_qs() as the wrapper of rcu_preempt_qs() is called
|
|
in some scenarios where irq is enabled, like this path,
|
|
|
|
do_single_softirq()
|
|
|
|
|
+ local_irq_enable();
|
|
+ handle_softirq()
|
|
| |
|
|
| + rcu_bh_qs()
|
|
| |
|
|
| + rcu_preempt_qs()
|
|
|
|
|
+ local_irq_disable()
|
|
|
|
So here we'd better disable irq directly inside of rcu_bh_qs() to
|
|
fix this, otherwise the kernel may be freezable sometimes as
|
|
observed. And especially this way is also kind and safe for the
|
|
potential rcu_bh_qs() usage elsewhere in the future.
|
|
|
|
|
|
Signed-off-by: Tiejun Chen <tiejun.chen@windriver.com>
|
|
Signed-off-by: Bin Jiang <bin.jiang@windriver.com>
|
|
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
|
|
---
|
|
kernel/rcu/tree.c | 5 +++++
|
|
1 file changed, 5 insertions(+)
|
|
|
|
--- a/kernel/rcu/tree.c
|
|
+++ b/kernel/rcu/tree.c
|
|
@@ -262,7 +262,12 @@ static void rcu_preempt_qs(void);
|
|
|
|
void rcu_bh_qs(void)
|
|
{
|
|
+ unsigned long flags;
|
|
+
|
|
+ /* Callers to this function, rcu_preempt_qs(), must disable irqs. */
|
|
+ local_irq_save(flags);
|
|
rcu_preempt_qs();
|
|
+ local_irq_restore(flags);
|
|
}
|
|
#else
|
|
void rcu_bh_qs(void)
|