diff options
author | Tiejun Chen <tiejun.chen@windriver.com> | 2013-12-18 17:51:49 +0800 |
---|---|---|
committer | Steven Rostedt <rostedt@rostedt.homelinux.com> | 2014-03-07 12:12:01 -0500 |
commit | 193d4d215f68318befcaa43cb135d90eb0935b52 (patch) | |
tree | e5f305762132ba0369e0f5c0b306c287eeae22cf | |
parent | 0d4f987ffadb8f1ccd54de891c649d9a6a104918 (diff) | |
download | linux-rt-193d4d215f68318befcaa43cb135d90eb0935b52.tar.gz |
rcutree/rcu_bh_qs: disable irq while calling rcu_preempt_qs()
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.
Cc: stable-rt@vger.kernel.org
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>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
-rw-r--r-- | kernel/rcutree.c | 5 |
1 files changed, 5 insertions, 0 deletions
diff --git a/kernel/rcutree.c b/kernel/rcutree.c index 7ec834de1640..6f6d1333bbcc 100644 --- a/kernel/rcutree.c +++ b/kernel/rcutree.c @@ -186,7 +186,12 @@ static void rcu_preempt_qs(int cpu); void rcu_bh_qs(int cpu) { + unsigned long flags; + + /* Callers to this function, rcu_preempt_qs(), must disable irqs. */ + local_irq_save(flags); rcu_preempt_qs(cpu); + local_irq_restore(flags); } #else void rcu_bh_qs(int cpu) |