Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752814Ab0HIFNc (ORCPT ); Mon, 9 Aug 2010 01:13:32 -0400 Received: from mail.windriver.com ([147.11.1.11]:39139 "EHLO mail.windriver.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752384Ab0HIFNT (ORCPT ); Mon, 9 Aug 2010 01:13:19 -0400 From: Jason Wessel To: paulmck@linux.vnet.ibm.com Cc: linux-kernel@vger.kernel.org, kgdb-bugreport@lists.sourceforge.net, Jason Wessel , Dipankar Sarma , Ingo Molnar Subject: [RFC PATCH 2/2] rcu,debug_core: allow the kernel debugger to reset the rcu stall timer Date: Mon, 9 Aug 2010 00:12:12 -0500 Message-Id: <1281330732-17164-3-git-send-email-jason.wessel@windriver.com> X-Mailer: git-send-email 1.6.4.rc1 In-Reply-To: <1281330732-17164-2-git-send-email-jason.wessel@windriver.com> References: <1281330732-17164-1-git-send-email-jason.wessel@windriver.com> <1281330732-17164-2-git-send-email-jason.wessel@windriver.com> X-OriginalArrivalTime: 09 Aug 2010 05:12:49.0615 (UTC) FILETIME=[82DEF5F0:01CB3781] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2831 Lines: 86 When returning from the kernel debugger allow a reset of the rcu jiffies_stall value to prevent the rcu stall detector from sending NMI events which stack dumps on all the cpus in the system. Signed-off-by: Jason Wessel CC: Dipankar Sarma CC: Paul E. McKenney CC: Ingo Molnar --- include/linux/rcupdate.h | 8 ++++++++ kernel/debug/debug_core.c | 2 ++ kernel/rcutree.c | 9 +++++++++ 3 files changed, 19 insertions(+), 0 deletions(-) diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h index 9fbc54a..abd3ab6 100644 --- a/include/linux/rcupdate.h +++ b/include/linux/rcupdate.h @@ -599,4 +599,12 @@ static inline void debug_rcu_head_unqueue(struct rcu_head *head) #define rcu_dereference_index_check(p, c) \ __rcu_dereference_index_check((p), (c)) +#ifdef CONFIG_RCU_CPU_STALL_DETECTOR +extern void rcu_cpu_stall_reset(void); +#else /* #ifdef CONFIG_RCU_CPU_STALL_DETECTOR */ +static inline void rcu_cpu_stall_reset(void) +{ +} +#endif /* #ifdef CONFIG_RCU_CPU_STALL_DETECTOR */ + #endif /* __LINUX_RCUPDATE_H */ diff --git a/kernel/debug/debug_core.c b/kernel/debug/debug_core.c index e4d6819..1600e90 100644 --- a/kernel/debug/debug_core.c +++ b/kernel/debug/debug_core.c @@ -47,6 +47,7 @@ #include #include #include +#include #include #include @@ -474,6 +475,7 @@ static void dbg_touch_watchdogs(void) { touch_softlockup_watchdog_sync(); clocksource_touch_watchdog(); + rcu_cpu_stall_reset(); } static int kgdb_cpu_enter(struct kgdb_state *ks, struct pt_regs *regs) diff --git a/kernel/rcutree.c b/kernel/rcutree.c index d5bc439..209b755 100644 --- a/kernel/rcutree.c +++ b/kernel/rcutree.c @@ -532,6 +532,9 @@ static void check_cpu_stall(struct rcu_state *rsp, struct rcu_data *rdp) if (rcu_cpu_stall_panicking) return; + /* Gracefully handle a watch dog reset when jiffies_stall == 0 */ + if (!rsp->jiffies_stall) + return; delta = jiffies - rsp->jiffies_stall; rnp = rdp->mynode; if ((rnp->qsmask & rdp->grpmask) && delta >= 0) { @@ -561,6 +564,12 @@ static void __init check_cpu_stall_init(void) atomic_notifier_chain_register(&panic_notifier_list, &rcu_panic_block); } +void rcu_cpu_stall_reset(void) +{ + rcu_sched_state.jiffies_stall = 0; + rcu_bh_state.jiffies_stall = 0; +} + #else /* #ifdef CONFIG_RCU_CPU_STALL_DETECTOR */ static void record_gp_stall_check_time(struct rcu_state *rsp) -- 1.6.3.3 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/