tracing: protect ring_buffer_expanded with trace_types_lock
Impact: prevent races with ring_buffer_expanded
This patch places the expanding of the tracing buffer under the
protection of the trace_types_lock mutex. It is highly unlikely
that there would be any contention, but better safe than sorry.
Reported-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index c61ee85..04ab824 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -2391,8 +2391,10 @@
{
int ret = 0;
+ mutex_lock(&trace_types_lock);
if (!ring_buffer_expanded)
ret = tracing_resize_ring_buffer(trace_buf_size);
+ mutex_unlock(&trace_types_lock);
return ret;
}
@@ -2412,6 +2414,8 @@
struct tracer *t;
int ret = 0;
+ mutex_lock(&trace_types_lock);
+
if (!ring_buffer_expanded) {
ret = tracing_resize_ring_buffer(trace_buf_size);
if (ret < 0)
@@ -2419,7 +2423,6 @@
ret = 0;
}
- mutex_lock(&trace_types_lock);
for (t = trace_types; t; t = t->next) {
if (strcmp(t->name, buf) == 0)
break;