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authorFrederic Weisbecker <fweisbec@gmail.com>2012-07-11 20:26:39 +0200
committerFrederic Weisbecker <fweisbec@gmail.com>2012-09-26 15:47:14 +0200
commitedf55fda35c7dc7f2d9241c3abaddaf759b457c6 (patch)
tree5350fcb03d0a6db3a212e11787c598d1df184df0 /arch/x86/kernel
parent0430499ce9d78691f3985962021b16bf8f8a8048 (diff)
x86: Exit RCU extended QS on notify resume
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>
Diffstat (limited to 'arch/x86/kernel')
-rw-r--r--arch/x86/kernel/signal.c4
1 files changed, 4 insertions, 0 deletions
diff --git a/arch/x86/kernel/signal.c b/arch/x86/kernel/signal.c
index b280908a376e..bca0ab903e57 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)