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 12:47:39 -0500 |
commit | 847ba06139981c4c590bc5252663c9e529e0d49c (patch) | |
tree | c950f52b69d68db0436ecd5bd5f3041596b40137 | |
parent | 9d3e1b65dba2ae5e7da9444b94f831f3bba30ac0 (diff) |
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 12ae4104ee1e..055268b44f8b 100644 --- a/kernel/rcutree.c +++ b/kernel/rcutree.c @@ -177,7 +177,12 @@ 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) |