When exceptions or irq are about to resume userspace, if the task needs to be rescheduled, the arch low level code calls schedule() directly.
At that time we may be in extended quiescent state from RCU POV: the exception is not anymore protected inside rcu_user_exit() - rcu_user_enter() and the irq has called rcu_irq_exit() already. Create a new API schedule_user() that calls schedule() inside rcu_user_exit()-rcu_user_enter() in order to protect it. Archs will need to rely on it now to implement user preemption safely. Signed-off-by: Frederic Weisbecker <[email protected]> Cc: Alessio Igor Bogani <[email protected]> Cc: Andrew Morton <[email protected]> Cc: Avi Kivity <[email protected]> Cc: Chris Metcalf <[email protected]> Cc: Christoph Lameter <[email protected]> Cc: Geoff Levand <[email protected]> Cc: Gilad Ben Yossef <[email protected]> Cc: Hakan Akkan <[email protected]> Cc: H. Peter Anvin <[email protected]> Cc: Ingo Molnar <[email protected]> Cc: Josh Triplett <[email protected]> Cc: Kevin Hilman <[email protected]> Cc: Max Krasnyansky <[email protected]> Cc: Peter Zijlstra <[email protected]> Cc: Stephen Hemminger <[email protected]> Cc: Steven Rostedt <[email protected]> Cc: Sven-Thorsten Dietrich <[email protected]> Cc: Thomas Gleixner <[email protected]> --- kernel/sched/core.c | 7 +++++++ 1 files changed, 7 insertions(+), 0 deletions(-) diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 1e0fa5b..a37619a 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -3332,6 +3332,13 @@ asmlinkage void __sched schedule(void) } EXPORT_SYMBOL(schedule); +asmlinkage void __sched schedule_user(void) +{ + rcu_user_exit(); + schedule(); + rcu_user_enter(); +} + /** * schedule_preempt_disabled - called with preemption disabled * -- 1.7.5.4 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
