Messages in this thread Patch in this message | | | From | "Paul E. McKenney" <> | Subject | [PATCH tip/core/rcu 11/26] rcu: Exit RCU extended QS on user preemption | Date | Thu, 30 Aug 2012 14:05:28 -0700 |
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From: Frederic Weisbecker <fweisbec@gmail.com>
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 <fweisbec@gmail.com> Cc: Alessio Igor Bogani <abogani@kernel.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Avi Kivity <avi@redhat.com> Cc: Chris Metcalf <cmetcalf@tilera.com> Cc: Christoph Lameter <cl@linux.com> Cc: Geoff Levand <geoff@infradead.org> Cc: Gilad Ben Yossef <gilad@benyossef.com> Cc: Hakan Akkan <hakanakkan@gmail.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Josh Triplett <josh@joshtriplett.org> Cc: Kevin Hilman <khilman@ti.com> Cc: Max Krasnyansky <maxk@qualcomm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Stephen Hemminger <shemminger@vyatta.com> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Sven-Thorsten Dietrich <thebigcorporation@gmail.com> Cc: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> --- 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 0bd599b..e841dfc 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -3463,6 +3463,13 @@ 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 * -- 1.7.8
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