dump_stack: avoid the livelock of the dump_lock

[platform/kernel/linux-rpi.git] / lib / dump_stack.c

diff --git a/lib/dump_stack.c b/lib/dump_stack.c
index 5cff72f..33ffbf3 100644 (file)
--- a/lib/dump_stack.c
+++ b/lib/dump_stack.c
@@ -106,7 +106,12 @@ retry:
                was_locked = 1;
        } else {
                local_irq_restore(flags);
-               cpu_relax();
+               /*
+                * 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;
        }