[GIT PULL] perf fix

[Ingo Molnar]

Linus,

Please pull the latest perf/urgent git tree from:

   git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git perf-urgent-2020-10-11

   # HEAD: 6d6b8b9f4fceab7266ca03d194f60ec72bd4b654 perf: Fix task_function_call() error handling

Fix an error handling bug that can cause a lockup if a CPU is offline. (doh ...)

 Thanks,

	Ingo

------------------>
Kajol Jain (1):
      perf: Fix task_function_call() error handling


 kernel/events/core.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/kernel/events/core.c b/kernel/events/core.c
index 7ed5248f0445..e8bf92202542 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -99,7 +99,7 @@ static void remote_function(void *data)
  * 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 @@ task_function_call(struct task_struct *p, remote_function_f func, void *info)
 	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;