[PATCH 02/16] tracing: protect ring_buffer_expanded with trace_types_lock

Steven Rostedt
2009-03-13T02:39:36Z

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From: Steven Rostedt <srostedt@redhat.com>

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>
---
kernel/trace/trace.c | 5 ++++-
1 files changed, 4 insertions(+), 1 deletions(-)

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 tracing_update_buffers(void)
{
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 @@ static int tracing_set_tracer(const char *buf)
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 @@ static int tracing_set_tracer(const char *buf)
ret = 0;
}

- mutex_lock(&trace_types_lock);
for (t = trace_types; t; t = t->next) {
if (strcmp(t->name, buf) == 0)
break;
--
1.6.1.3

--