On Thu, Aug 30, 2012 at 02:05:30PM -0700, Paul E. McKenney wrote: > From: Frederic Weisbecker <[email protected]> > > do_notify_resume() may be called on irq or exception > exit. But at that time the exception has already called > rcu_user_enter() and the irq has already called rcu_irq_exit(). > > Since it can use RCU read side critical section, we must call > rcu_user_exit() before doing anything there. Then we must call > back rcu_user_enter() after this function because we know we are > going to userspace from there. > > This complete support for userspace RCU extended quiescent state > in x86-64. > > 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]> > Signed-off-by: Paul E. McKenney <[email protected]>
Reviewed-by: Josh Triplett <[email protected]> > arch/x86/Kconfig | 1 + > arch/x86/kernel/signal.c | 4 ++++ > 2 files changed, 5 insertions(+), 0 deletions(-) > > diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig > index ba2657c..5cd953a 100644 > --- a/arch/x86/Kconfig > +++ b/arch/x86/Kconfig > @@ -97,6 +97,7 @@ 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 > > config INSTRUCTION_DECODER > def_bool (KPROBES || PERF_EVENTS || UPROBES) > diff --git a/arch/x86/kernel/signal.c b/arch/x86/kernel/signal.c > index b280908..bca0ab9 100644 > --- a/arch/x86/kernel/signal.c > +++ b/arch/x86/kernel/signal.c > @@ -779,6 +779,8 @@ 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) > @@ -804,6 +806,8 @@ do_notify_resume(struct pt_regs *regs, void *unused, > __u32 thread_info_flags) > #ifdef CONFIG_X86_32 > clear_thread_flag(TIF_IRET); > #endif /* CONFIG_X86_32 */ > + > + rcu_user_enter(); > } > > void signal_fault(struct pt_regs *regs, void __user *frame, char *where) > -- > 1.7.8 > -- 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/
