Merge tag 'perf-urgent-2020-10-11' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull perf fix from Ingo Molnar:
"Fix an error handling bug that can cause a lockup if a CPU is offline
(doh ...)"
* tag 'perf-urgent-2020-10-11' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
perf: Fix task_function_call() error handling
diff --git a/kernel/events/core.c b/kernel/events/core.c
index 7ed5248..e8bf9220 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -99,7 +99,7 @@
* retry due to any failures in smp_call_function_single(), such as if the
* task_cpu() goes offline concurrently.
*
- * returns @func return value or -ESRCH when the process isn't running
+ * returns @func return value or -ESRCH or -ENXIO when the process isn't running
*/
static int
task_function_call(struct task_struct *p, remote_function_f func, void *info)
@@ -115,7 +115,8 @@
for (;;) {
ret = smp_call_function_single(task_cpu(p), remote_function,
&data, 1);
- ret = !ret ? data.ret : -EAGAIN;
+ if (!ret)
+ ret = data.ret;
if (ret != -EAGAIN)
break;
