From 4627e240dfee4a0a46a58010b1b721b4ded1918f Mon Sep 17 00:00:00 2001 From: "Paul E. McKenney" Date: Wed, 3 Aug 2011 03:34:24 -0700 Subject: [PATCH] rcu: Dump local stack if cannot dump all CPUs' stacks The trigger_all_cpu_backtrace() function is a no-op in architectures that do not define arch_trigger_all_cpu_backtrace. On such architectures, RCU CPU stall warning messages contain no stack trace information, which makes debugging quite difficult. This commit therefore substitutes dump_stack() for architectures that do not define arch_trigger_all_cpu_backtrace, so that at least the local CPU's stack is dumped as part of the RCU CPU stall warning message. Signed-off-by: Paul E. McKenney --- kernel/rcutree.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/kernel/rcutree.c b/kernel/rcutree.c index ebd18e56947b..a07bf553e02a 100644 --- a/kernel/rcutree.c +++ b/kernel/rcutree.c @@ -583,7 +583,8 @@ static void print_other_cpu_stall(struct rcu_state *rsp) } printk("} (detected by %d, t=%ld jiffies)\n", smp_processor_id(), (long)(jiffies - rsp->gp_start)); - trigger_all_cpu_backtrace(); + if (!trigger_all_cpu_backtrace()) + dump_stack(); /* If so configured, complain about tasks blocking the grace period. */ @@ -604,7 +605,8 @@ static void print_cpu_stall(struct rcu_state *rsp) */ printk(KERN_ERR "INFO: %s detected stall on CPU %d (t=%lu jiffies)\n", rsp->name, smp_processor_id(), jiffies - rsp->gp_start); - trigger_all_cpu_backtrace(); + if (!trigger_all_cpu_backtrace()) + dump_stack(); raw_spin_lock_irqsave(&rnp->lock, flags); if (ULONG_CMP_GE(jiffies, rsp->jiffies_stall)) -- 2.34.1