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authorFrederic Weisbecker <fweisbec@gmail.com>2013-02-24 12:59:30 +0100
committerFrederic Weisbecker <fweisbec@gmail.com>2013-03-07 17:10:21 +0100
commitb22366cd54c6fe05db426f20adb10f461c19ec06 (patch)
tree3eb42a6ae0c6b25c27d946e6ffa4787f82ac952f /kernel/sched
parent6c1e0256fad84a843d915414e4b5973b7443d48d (diff)
downloadlinaro-lsk-b22366cd54c6fe05db426f20adb10f461c19ec06.tar.gz
context_tracking: Restore preempted context state after preempt_schedule_irq()
From the context tracking POV, preempt_schedule_irq() behaves pretty much like an exception: It can be called anytime and schedule another task. But currently it doesn't restore the context tracking state of the preempted code on preempt_schedule_irq() return. As a result, if preempt_schedule_irq() is called in the tiny frame between user_enter() and the actual return to userspace, we resume userspace with the wrong context tracking state. Fix this by using exception_enter/exit() which are a perfect fit for this kind of issue. Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Cc: Li Zhong <zhong@linux.vnet.ibm.com> Cc: Kevin Hilman <khilman@linaro.org> Cc: Mats Liljegren <mats.liljegren@enea.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Ingo Molnar <mingo@kernel.org> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Namhyung Kim <namhyung.kim@lge.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Diffstat (limited to 'kernel/sched')
-rw-r--r--kernel/sched/core.c6
1 files changed, 5 insertions, 1 deletions
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 7f12624a393..af7a8c84b79 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -3082,11 +3082,13 @@ EXPORT_SYMBOL(preempt_schedule);
asmlinkage void __sched preempt_schedule_irq(void)
{
struct thread_info *ti = current_thread_info();
+ enum ctx_state prev_state;
/* Catch callers which need to be fixed */
BUG_ON(ti->preempt_count || !irqs_disabled());
- user_exit();
+ prev_state = exception_enter();
+
do {
add_preempt_count(PREEMPT_ACTIVE);
local_irq_enable();
@@ -3100,6 +3102,8 @@ asmlinkage void __sched preempt_schedule_irq(void)
*/
barrier();
} while (need_resched());
+
+ exception_exit(prev_state);
}
#endif /* CONFIG_PREEMPT */