diff options
authorSteven Rostedt (Red Hat) <rostedt@goodmis.org>2013-07-24 02:21:59 (GMT)
committerSteven Rostedt <rostedt@goodmis.org>2013-07-26 12:57:32 (GMT)
commit09d8091c024ec88d1541d93eb8ddb2bd5cf10c39 (patch)
parent195a8afc7ac962f8da795549fe38e825f1372b0d (diff)
tracing: Remove locking trace_types_lock from tracing_reset_all_online_cpus()
Commit a82274151af "tracing: Protect ftrace_trace_arrays list in trace_events.c" added taking the trace_types_lock mutex in trace_events.c as there were several locations that needed it for protection. Unfortunately, it also encapsulated a call to tracing_reset_all_online_cpus() which also takes the trace_types_lock, causing a deadlock. This happens when a module has tracepoints and has been traced. When the module is removed, the trace events module notifier will grab the trace_types_lock, do a bunch of clean ups, and also clears the buffer by calling tracing_reset_all_online_cpus. This doesn't happen often which explains why it wasn't caught right away. Commit a82274151af was marked for stable, which means this must be sent to stable too. Link: http://lkml.kernel.org/r/51EEC646.7070306@broadcom.com Reported-by: Arend van Spril <arend@broadcom.com> Tested-by: Arend van Spriel <arend@broadcom.com> Cc: Alexander Z Lam <azl@google.com> Cc: Vaibhav Nagarnaik <vnagarnaik@google.com> Cc: David Sharp <dhsharp@google.com> Cc: stable@vger.kernel.org # 3.10 Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
1 files changed, 1 insertions, 2 deletions
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 69cba47..882ec1d 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -1224,18 +1224,17 @@ void tracing_reset_current(int cpu)
tracing_reset(&global_trace.trace_buffer, cpu);
+/* Must have trace_types_lock held */
void tracing_reset_all_online_cpus(void)
struct trace_array *tr;
- mutex_lock(&trace_types_lock);
list_for_each_entry(tr, &ftrace_trace_arrays, list) {
- mutex_unlock(&trace_types_lock);
#define SAVED_CMDLINES 128

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