Messages in this thread | | | Date | Fri, 31 Aug 2012 16:52:25 -0700 | From | Josh Triplett <> | Subject | Re: [PATCH tip/core/rcu 11/26] rcu: Exit RCU extended QS on user preemption |
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On Thu, Aug 30, 2012 at 02:05:28PM -0700, Paul E. McKenney wrote: > 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>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
> 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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