Commit 2519c1bb authored Jul 25, 2018 by Steven Rostedt (VMware)

tracing: Quiet gcc warning about maybe unused link variable



Commit 57ea2a34 ("tracing/kprobes: Fix trace_probe flags on
enable_trace_kprobe() failure") added an if statement that depends on another
if statement that gcc doesn't see will initialize the "link" variable and
gives the warning:

 "warning: 'link' may be used uninitialized in this function"

It is really a false positive, but to quiet the warning, and also to make
sure that it never actually is used uninitialized, initialize the "link"
variable to NULL and add an if (!WARN_ON_ONCE(!link)) where the compiler
thinks it could be used uninitialized.

Cc: stable@vger.kernel.org
Fixes: 57ea2a34 ("tracing/kprobes: Fix trace_probe flags on enable_trace_kprobe() failure")
Reported-by: kbuild test robot <lkp@intel.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

parent 15cc7864

kernel/trace/trace_kprobe.c

+4 −2

Original line number	Diff line number	Diff line
		@@ -400,7 +400,7 @@ static struct trace_kprobe find_trace_kprobe(const char event,
		static int
		enable_trace_kprobe(struct trace_kprobe tk, struct trace_event_file file)
		{
		struct event_file_link *link;
		struct event_file_link *link = NULL;
		int ret = 0;

		if (file) {
		@@ -426,6 +426,8 @@ enable_trace_kprobe(struct trace_kprobe tk, struct trace_event_file file)

		if (ret) {
		if (file) {
		/* Notice the if is true on not WARN() */
		if (!WARN_ON_ONCE(!link))
		list_del_rcu(&link->list);
		kfree(link);
		tk->tp.flags &= ~TP_FLAG_TRACE;