| Message ID | 1346360743-3628-13-git-send-email-paulmck@linux.vnet.ibm.com |
|---|---|
| State | Accepted |
| Commit | edf55fda35c7dc7f2d9241c3abaddaf759b457c6 |
| Headers | show |
On Thu, Aug 30, 2012 at 02:05:30PM -0700, Paul E. McKenney wrote: > From: Frederic Weisbecker <fweisbec@gmail.com> > > 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 <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> > 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 >
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)