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

[weiyj_lk]

From: Wei Yongjun <yongjun_...@trendmicro.com.cn>

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().

Signed-off-by: Wei Yongjun <yongjun_...@trendmicro.com.cn>
---
 kernel/trace/ring_buffer.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c
index 9c14373..f30847a 100644
--- a/kernel/trace/ring_buffer.c
+++ b/kernel/trace/ring_buffer.c
@@ -4870,9 +4870,9 @@ 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;
                }
 
@@ -4882,9 +4882,9 @@ 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;
        }