From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1031096Ab2CUOCO (ORCPT ); Wed, 21 Mar 2012 10:02:14 -0400 Received: from mail-wg0-f44.google.com ([74.125.82.44]:47416 "EHLO mail-wg0-f44.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1031081Ab2CUOAN (ORCPT ); Wed, 21 Mar 2012 10:00:13 -0400 From: Frederic Weisbecker To: LKML , linaro-sched-sig@lists.linaro.org Cc: Frederic Weisbecker , Alessio Igor Bogani , Andrew Morton , Avi Kivity , Chris Metcalf , Christoph Lameter , Daniel Lezcano , Geoff Levand , Gilad Ben Yossef , Ingo Molnar , Max Krasnyansky , "Paul E. McKenney" , Peter Zijlstra , Stephen Hemminger , Steven Rostedt , Sven-Thorsten Dietrich , Thomas Gleixner , Zen Lin Subject: [PATCH 26/32] x86: Add adaptive tickless hooks on do_notify_resume() Date: Wed, 21 Mar 2012 14:58:32 +0100 Message-Id: <1332338318-5958-28-git-send-email-fweisbec@gmail.com> X-Mailer: git-send-email 1.7.5.4 In-Reply-To: <1332338318-5958-1-git-send-email-fweisbec@gmail.com> References: <1332338318-5958-1-git-send-email-fweisbec@gmail.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Before resuming to userspace, we may fall into do_notify_resume() to handle signals or other things. And because we may be coming from syscall/exception or interrupt exit, we may be running into RCU idle mode as we resume tickless to userspace. However do_notify_resume() may make use of RCU read side critical sections so we need to exit RCU idle mode before doing anything in that path. Signed-off-by: Frederic Weisbecker Cc: Alessio Igor Bogani Cc: Andrew Morton Cc: Avi Kivity Cc: Chris Metcalf Cc: Christoph Lameter Cc: Daniel Lezcano Cc: Geoff Levand Cc: Gilad Ben Yossef Cc: Ingo Molnar Cc: Max Krasnyansky Cc: Paul E. McKenney Cc: Peter Zijlstra Cc: Stephen Hemminger Cc: Steven Rostedt Cc: Sven-Thorsten Dietrich Cc: Thomas Gleixner Cc: Zen Lin --- arch/x86/kernel/signal.c | 3 +++ 1 files changed, 3 insertions(+), 0 deletions(-) diff --git a/arch/x86/kernel/signal.c b/arch/x86/kernel/signal.c index 46a01bd..577fd93 100644 --- a/arch/x86/kernel/signal.c +++ b/arch/x86/kernel/signal.c @@ -20,6 +20,7 @@ #include #include #include +#include #include #include @@ -810,6 +811,7 @@ static void do_signal(struct pt_regs *regs) void do_notify_resume(struct pt_regs *regs, void *unused, __u32 thread_info_flags) { + tick_nohz_enter_kernel(); #ifdef CONFIG_X86_MCE /* notify userspace of pending MCEs */ if (thread_info_flags & _TIF_MCE_NOTIFY) @@ -832,6 +834,7 @@ 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 */ + tick_nohz_exit_kernel(); } void signal_fault(struct pt_regs *regs, void __user *frame, char *where) -- 1.7.5.4