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author | Alex Thorlton <athorlton@sgi.com> | 2013-07-03 15:04:59 -0700 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2013-07-03 16:07:41 -0700 |
commit | b58d977432c80ee60d6970042775a62e3f8d7675 (patch) | |
tree | ca998b67437265115d2d242b47f2ac52fa0091c5 /lib/dump_stack.c | |
parent | f170168b9a0b61ea1e647b082b38f605f1d3de3e (diff) | |
download | linux-stable-b58d977432c80ee60d6970042775a62e3f8d7675.tar.gz linux-stable-b58d977432c80ee60d6970042775a62e3f8d7675.tar.bz2 linux-stable-b58d977432c80ee60d6970042775a62e3f8d7675.zip |
dump_stack: serialize the output from dump_stack()
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>
Diffstat (limited to 'lib/dump_stack.c')
-rw-r--r-- | lib/dump_stack.c | 47 |
1 files changed, 45 insertions, 2 deletions
diff --git a/lib/dump_stack.c b/lib/dump_stack.c index 53bad099ebd6..c03154173cc7 100644 --- a/lib/dump_stack.c +++ b/lib/dump_stack.c @@ -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); |