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dump_stack: serialize the output from dump_stack()

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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>
This commit is contained in:
Alex Thorlton 2013-07-03 15:04:59 -07:00 committed by Linus Torvalds
parent f170168b9a
commit b58d977432
1 changed files with 45 additions and 2 deletions
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47
lib/dump_stack.c
View File

@ -6,15 +6,58 @@
#include <linux/kernel.h> #include <linux/kernel.h>
#include <linux/export.h> #include <linux/export.h>
#include <linux/sched.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 * dump_stack - dump the current task information and its stack trace
* *
* Architectures can override this implementation by implementing its own. * Architectures can override this implementation by implementing its own.
*/ */
#ifdef CONFIG_SMP
static atomic_t dump_lock = ATOMIC_INIT(-1);
void dump_stack(void) void dump_stack(void)
{ {
dump_stack_print_info(KERN_DEFAULT); int was_locked;
show_stack(NULL, NULL); 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); EXPORT_SYMBOL(dump_stack);