dump_stack: serialize the output from dump_stack() (b58d9774) · Commits · 戴 / test

Add functionality to serialize the output from dump_stack() to avoid mangling of the output when dump_stack is called simultaneously from multiple cpus. [akpm@linux-foundation.org: fix comment indenting, avoid inclusion of <asm/> files - use <linux/> where possiblem fix uniprocessor build (__dump_stack undefined), remove unneeded ifdef around smp.h inclusion] Signed-off-by:

Alex Thorlton <athorlton@sgi.com> Reported-by:

Russ Anderson <rja@sgi.com> Reviewed-by:

Robin Holt <holt@sgi.com> Cc: Vineet Gupta <vgupta@synopsys.com> Cc: David S. Miller <davem@davemloft.net> Cc: Richard Kuo <rkuo@codeaurora.org> Cc: Jesper Nilsson <jesper.nilsson@axis.com> Signed-off-by:

Andrew Morton <akpm@linux-foundation.org> Signed-off-by:

Linus Torvalds <torvalds@linux-foundation.org>

lib/dump_stack.c

+45 −2

Original line number	Diff line number	Diff line
		@@ -6,15 +6,58 @@
		#include <linux/kernel.h>
		#include <linux/export.h>
		#include <linux/sched.h>
		#include <linux/smp.h>
		#include <linux/atomic.h>

		static void __dump_stack(void)
		{
		dump_stack_print_info(KERN_DEFAULT);
		show_stack(NULL, NULL);
		}

		/**
		* dump_stack - dump the current task information and its stack trace
		*
		* Architectures can override this implementation by implementing its own.
		*/
		#ifdef CONFIG_SMP
		static atomic_t dump_lock = ATOMIC_INIT(-1);

		void dump_stack(void)
		{
		dump_stack_print_info(KERN_DEFAULT);
		show_stack(NULL, NULL);
		int was_locked;
		int old;
		int cpu;

		/*
		* Permit this cpu to perform nested stack dumps while serialising
		* against other CPUs
		*/
		preempt_disable();

		retry:
		cpu = smp_processor_id();
		old = atomic_cmpxchg(&dump_lock, -1, cpu);
		if (old == -1) {
		was_locked = 0;
		} else if (old == cpu) {
		was_locked = 1;
		} else {
		cpu_relax();
		goto retry;
		}

		__dump_stack();

		if (!was_locked)
		atomic_set(&dump_lock, -1);

		preempt_enable();
		}
		#else
		void dump_stack(void)
		{
		__dump_stack();
		}
		#endif
		EXPORT_SYMBOL(dump_stack);

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