asmlinkage __visible void dump_stack(void)
{
+ unsigned long flags;
int was_locked;
int old;
int cpu;
* Permit this cpu to perform nested stack dumps while serialising
* against other CPUs
*/
- preempt_disable();
-
retry:
+ local_irq_save(flags);
cpu = smp_processor_id();
old = atomic_cmpxchg(&dump_lock, -1, cpu);
if (old == -1) {
} else if (old == cpu) {
was_locked = 1;
} else {
- cpu_relax();
+ local_irq_restore(flags);
+ /*
+ * Wait for the lock to release before jumping to
+ * atomic_cmpxchg() in order to mitigate the thundering herd
+ * problem.
+ */
+ do { cpu_relax(); } while (atomic_read(&dump_lock) != -1);
goto retry;
}
if (!was_locked)
atomic_set(&dump_lock, -1);
- preempt_enable();
+ local_irq_restore(flags);
}
#else
asmlinkage __visible void dump_stack(void)