[GIT PULL] ring-buffer: Fix return value check in test_ringbuffer()

[Steven Rostedt]

Linus,

Wei Yongjun fixed a long standing bug in the ring buffer startup test.
If for some unknown reason, the kthread that is created fails to be
created, the return from kthread_create() is an PTR_ERR and not a NULL.
The test incorrectly checks for NULL instead of an error.


Please pull the latest trace-v4.11-rc5 tree, which can be found at:


  git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace.git
trace-v4.11-rc5

Tag SHA1: 727df954e9f7ff3ac10b34633ef3109ce7fcded7
Head SHA1: 62277de758b155dc04b78f195a1cb5208c37b2df


Wei Yongjun (1):
      ring-buffer: Fix return value check in test_ringbuffer()

----
 kernel/trace/ring_buffer.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)
---------------------------
commit 62277de758b155dc04b78f195a1cb5208c37b2df
Author: Wei Yongjun <yongjun_wei@xxxxxxxxxxxxxxxxx>
Date:   Fri Jun 17 17:33:59 2016 +0000

    ring-buffer: Fix return value check in test_ringbuffer()
    
    In case of error, the function kthread_run() returns ERR_PTR()
    and never returns NULL. The NULL test in the return value check
    should be replaced with IS_ERR().
    
    Link: http://lkml.kernel.org/r/1466184839-14927-1-git-send-email-weiyj_lk@xxxxxxx
    
    Cc: stable@xxxxxxxxxxxxxxx
    Fixes: 6c43e554a ("ring-buffer: Add ring buffer startup selftest")
    Signed-off-by: Wei Yongjun <yongjun_wei@xxxxxxxxxxxxxxxxx>
    Signed-off-by: Steven Rostedt (VMware) <rostedt@xxxxxxxxxxx>

diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c
index 96fc3c043ad6..54e7a90db848 100644
--- a/kernel/trace/ring_buffer.c
+++ b/kernel/trace/ring_buffer.c
@@ -4826,9 +4826,9 @@ static __init int test_ringbuffer(void)
 		rb_data[cpu].cnt = cpu;
 		rb_threads[cpu] = kthread_create(rb_test, &rb_data[cpu],
 						 "rbtester/%d", cpu);
-		if (WARN_ON(!rb_threads[cpu])) {
+		if (WARN_ON(IS_ERR(rb_threads[cpu]))) {
 			pr_cont("FAILED\n");
-			ret = -1;
+			ret = PTR_ERR(rb_threads[cpu]);
 			goto out_free;
 		}
 
@@ -4838,9 +4838,9 @@ static __init int test_ringbuffer(void)
 
 	/* Now create the rb hammer! */
 	rb_hammer = kthread_run(rb_hammer_test, NULL, "rbhammer");
-	if (WARN_ON(!rb_hammer)) {
+	if (WARN_ON(IS_ERR(rb_hammer))) {
 		pr_cont("FAILED\n");
-		ret = -1;
+		ret = PTR_ERR(rb_hammer);
 		goto out_free;
 	}