[RFC PATCH 2/2] rcu,debug_core: allow the kernel debugger to reset the rcu stall timer
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From: Jason Wessel on 9 Aug 2010 01:20 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 <jason.wessel(a)windriver.com> CC: Dipankar Sarma <dipankar(a)in.ibm.com> CC: Paul E. McKenney <paulmck(a)linux.vnet.ibm.com> CC: Ingo Molnar <mingo(a)elte.hu> --- 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 <linux/pid.h> #include <linux/smp.h> #include <linux/mm.h> +#include <linux/rcupdate.h> #include <asm/cacheflush.h> #include <asm/byteorder.h> @@ -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(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/ |