Messages in this thread | | | Date | Fri, 6 Jul 2012 09:33:38 -0700 | From | "Paul E. McKenney" <> | Subject | Re: [PATCH 6/6] x86: Exit RCU extended QS on notify resume |
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On Fri, Jul 06, 2012 at 02:00:18PM +0200, Frederic Weisbecker wrote: > do_notify_resume() may be called on irq exit but it won't > be protected between rcu_irq_enter() and rcu_irq_exit() > and we don't call rcu_user_exit() on irq entry (unlike > syscalls/exceptions entry). > > Since it can use RCU read side critical section, we must call > rcu_user_exit() before doing anything there. > > This complete support for RCU userspace extended quiescent state > in x86. > > 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> > --- > arch/x86/Kconfig | 1 + > arch/x86/kernel/signal.c | 2 ++ > 2 files changed, 3 insertions(+), 0 deletions(-) > > diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig > index c70684f..38dfcc2 100644 > --- a/arch/x86/Kconfig > +++ b/arch/x86/Kconfig > @@ -95,6 +95,7 @@ config X86 > select KTIME_SCALAR if X86_32 > select GENERIC_STRNCPY_FROM_USER > select GENERIC_STRNLEN_USER > + select HAVE_RCU_USER_QS if X86_64
And I will bite yet again. Why only 64-bit kernels?
Thanx, Paul
> config INSTRUCTION_DECODER > def_bool (KPROBES || PERF_EVENTS || UPROBES) > diff --git a/arch/x86/kernel/signal.c b/arch/x86/kernel/signal.c > index 21af737..5af078e 100644 > --- a/arch/x86/kernel/signal.c > +++ b/arch/x86/kernel/signal.c > @@ -776,6 +776,8 @@ static void do_signal(struct pt_regs *regs) > void > do_notify_resume(struct pt_regs *regs, void *unused, __u32 thread_info_flags) > { > + rcu_user_exit(); > + > #ifdef CONFIG_X86_MCE > /* notify userspace of pending MCEs */ > if (thread_info_flags & _TIF_MCE_NOTIFY) > -- > 1.7.5.4 >
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