Pull tracing fix from Steven Rostedt:
"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"
* tag 'trace-v4.11-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace:
ring-buffer: Fix return value check in test_ringbuffer()