The patch titled
Subject: dump_stack: serialize the output from dump_stack()
has been added to the -mm tree. Its filename is
dump_stack-serialize-the-output-from-dump_stack.patch
Before you just go and hit "reply", please:
a) Consider who else should be cc'ed
b) Prefer to cc a suitable mailing list as well
c) Ideally: find the original patch on the mailing list and do a
reply-to-all to that, adding suitable additional cc's
*** Remember to use Documentation/SubmitChecklist when testing your code ***
The -mm tree is included into linux-next and is updated
there every 3-4 working days
------------------------------------------------------
From: Alex Thorlton <athorlton@xxxxxxx>
Subject: dump_stack: serialize the output from dump_stack()
tAdd adds functionality to serialize the output from dump_stack() to avoid
mangling of the output when dump_stack is called simultaneously from
multiple cpus.
Signed-off-by: Alex Thorlton <athorlton@xxxxxxx>
Reported-by: Russ Anderson <rja@xxxxxxx>
Reviewed-by: Robin Holt <holt@xxxxxxx>
Cc: Vineet Gupta <vgupta@xxxxxxxxxxxx>
Cc: David S. Miller <davem@xxxxxxxxxxxxx>
Cc: Richard Kuo <rkuo@xxxxxxxxxxxxxx>
Cc: Jesper Nilsson <jesper.nilsson@xxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
lib/dump_stack.c | 49 ++++++++++++++++++++++++++++++++++++++++++++-
1 file changed, 48 insertions(+), 1 deletion(-)
diff -puN lib/dump_stack.c~dump_stack-serialize-the-output-from-dump_stack lib/dump_stack.c
--- a/lib/dump_stack.c~dump_stack-serialize-the-output-from-dump_stack
+++ a/lib/dump_stack.c
@@ -6,15 +6,62 @@
#include <linux/kernel.h>
#include <linux/export.h>
#include <linux/sched.h>
+#include <asm/processor.h>
+#include <asm/atomic.h>
+
+#ifdef CONFIG_SMP
+#include <linux/smp.h>
+#endif
/**
* 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)
{
+ 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);
+
+static void __dump_stack(void)
+{
dump_stack_print_info(KERN_DEFAULT);
show_stack(NULL, NULL);
}
-EXPORT_SYMBOL(dump_stack);
_
Patches currently in -mm which might be from athorlton@xxxxxxx are
origin.patch
dump_stack-serialize-the-output-from-dump_stack.patch
dump_stack-serialize-the-output-from-dump_stack-fix.patch
panic-add-cpu-pid-to-warn_slowpath_common-in-warning-printks.patch
--
To unsubscribe from this list: send the line "unsubscribe mm-commits" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
