tree 8759aecdfd21821ebc63269c6c6b9424c325839a
parent 8b2653de6f78741b6e5217fc74b538a7f67f1a82
author Steven Rostedt (VMware) <rostedt@goodmis.org> 1508266524 -0400
committer Greg Kroah-Hartman <gregkh@linuxfoundation.org> 1510132112 +0100

tracing/samples: Fix creation and deletion of simple_thread_fn creation

commit 6575257c60e1a26a5319ccf2b5ce5b6449001017 upstream.

Commit 7496946a8 ("tracing: Add samples of DECLARE_EVENT_CLASS() and
DEFINE_EVENT()") added template examples for all the events. It created a
DEFINE_EVENT_FN() example which reused the foo_bar_reg and foo_bar_unreg
functions.

Enabling both the TRACE_EVENT_FN() and DEFINE_EVENT_FN() example trace
events caused the foo_bar_reg to be called twice, creating the test thread
twice. The foo_bar_unreg would remove it only once, even if it was called
multiple times, leaving a thread existing when the module is unloaded,
causing an oops.

Add a ref count and allow foo_bar_reg() and foo_bar_unreg() be called by
multiple trace events.

Fixes: 7496946a8 ("tracing: Add samples of DECLARE_EVENT_CLASS() and DEFINE_EVENT()")
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>