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tracing: Quiet gcc warning about maybe unused link variable 

commit 2519c1bbe3 upstream.

Commit 57ea2a34ad ("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: 57ea2a34ad ("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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
pull/10/head
Steven Rostedt (VMware) 2018-07-25 22:28:56 -04:00 committed by Greg Kroah-Hartman
parent 86428ec165
commit 4681e8820f
1 changed files with 4 additions and 2 deletions
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6
kernel/trace/trace_kprobe.c
View File

@ -376,7 +376,7 @@ 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) {
@ -402,7 +402,9 @@ enable_trace_kprobe(struct trace_kprobe *tk, struct trace_event_file *file)
if (ret) {
if (file) {
list_del_rcu(&link->list);
/* 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;
} else {