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Commit 4627e240 authored by Paul E. McKenney's avatar Paul E. McKenney
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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: default avatarPaul E. McKenney <paulmck@linux.vnet.ibm.com>
parent 6206ab9b

kernel/rcutree.c

+4 −2
Original line number Diff line number Diff line
@@ -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))