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-rw-r--r--kernel/panic.c26
1 files changed, 23 insertions, 3 deletions
diff --git a/kernel/panic.c b/kernel/panic.c
index 3458469eb7c..80aed44e345 100644
--- a/kernel/panic.c
+++ b/kernel/panic.c
@@ -49,6 +49,15 @@ static long no_blink(int state)
long (*panic_blink)(int state);
EXPORT_SYMBOL(panic_blink);
+/*
+ * Stop ourself in panic -- architecture code may override this
+ */
+void __weak panic_smp_self_stop(void)
+{
+ while (1)
+ cpu_relax();
+}
+
/**
* panic - halt the system
* @fmt: The text string to print
@@ -57,8 +66,9 @@ EXPORT_SYMBOL(panic_blink);
*
* This function never returns.
*/
-NORET_TYPE void panic(const char * fmt, ...)
+void panic(const char *fmt, ...)
{
+ static DEFINE_SPINLOCK(panic_lock);
static char buf[1024];
va_list args;
long i, i_next = 0;
@@ -68,8 +78,14 @@ NORET_TYPE void panic(const char * fmt, ...)
* It's possible to come here directly from a panic-assertion and
* not have preempt disabled. Some functions called from here want
* preempt to be disabled. No point enabling it later though...
+ *
+ * Only one CPU is allowed to execute the panic code from here. For
+ * multiple parallel invocations of panic, all other CPUs either
+ * stop themself or will wait until they are stopped by the 1st CPU
+ * with smp_send_stop().
*/
- preempt_disable();
+ if (!spin_trylock(&panic_lock))
+ panic_smp_self_stop();
console_verbose();
bust_spinlocks(1);
@@ -78,7 +94,11 @@ NORET_TYPE void panic(const char * fmt, ...)
va_end(args);
printk(KERN_EMERG "Kernel panic - not syncing: %s\n",buf);
#ifdef CONFIG_DEBUG_BUGVERBOSE
- dump_stack();
+ /*
+ * Avoid nested stack-dumping if a panic occurs during oops processing
+ */
+ if (!oops_in_progress)
+ dump_stack();
#endif
/*