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authorAlex Thorlton <athorlton@sgi.com>2013-07-03 15:04:59 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2013-07-03 16:07:41 -0700
commitb58d977432c80ee60d6970042775a62e3f8d7675 (patch)
treeca998b67437265115d2d242b47f2ac52fa0091c5 /lib/dump_stack.c
parentf170168b9a0b61ea1e647b082b38f605f1d3de3e (diff)
downloadlinux-sh-b58d977432c80ee60d6970042775a62e3f8d7675.tar.gz
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.c47
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);