tracing: fix oops in tracepoint_update_probe_range()
Change this crash:
BUG: unable to handle kernel NULL pointer dereference at (null)
IP: [<ffffffff8107d4de>] tracepoint_update_probe_range+0x1f/0x9b
PGD 13d5fb067 PUD 13d688067 PMD 0
Oops: 0000 [#1] SMP
To a more debuggable WARN_ONCE().
Signed-off-by: Jaswinder Singh Rajput <jaswinderrajput@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
LKML-Reference: <1237394936.3132.1.camel@localhost.localdomain>
[ moved the check outside the lock and added a WARN_ON(). ]
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/kernel/tracepoint.c b/kernel/tracepoint.c
index 7960274..adf2873 100644
--- a/kernel/tracepoint.c
+++ b/kernel/tracepoint.c
@@ -272,12 +272,17 @@
*
* Updates the probe callback corresponding to a range of tracepoints.
*/
-void tracepoint_update_probe_range(struct tracepoint *begin,
- struct tracepoint *end)
+void
+tracepoint_update_probe_range(struct tracepoint *begin, struct tracepoint *end)
{
struct tracepoint *iter;
struct tracepoint_entry *mark_entry;
+ if (!begin) {
+ WARN_ON_ONCE(1);
+ return;
+ }
+
mutex_lock(&tracepoints_mutex);
for (iter = begin; iter < end; iter++) {
mark_entry = get_tracepoint(iter->name);
