3.10-stable review patch. If anyone has any objections, please let me know.
------------------ From: "Steven Rostedt (Red Hat)" <rost...@goodmis.org> commit 09d8091c024ec88d1541d93eb8ddb2bd5cf10c39 upstream. 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/51eec646.7070...@broadcom.com Reported-by: Arend van Spril <ar...@broadcom.com> Tested-by: Arend van Spriel <ar...@broadcom.com> Cc: Alexander Z Lam <a...@google.com> Cc: Vaibhav Nagarnaik <vnagarn...@google.com> Cc: David Sharp <dhsh...@google.com> Signed-off-by: Steven Rostedt <rost...@goodmis.org> Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org> --- kernel/trace/trace.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -1163,18 +1163,17 @@ 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) { tracing_reset_online_cpus(&tr->trace_buffer); #ifdef CONFIG_TRACER_MAX_TRACE tracing_reset_online_cpus(&tr->max_buffer); #endif } - mutex_unlock(&trace_types_lock); } #define SAVED_CMDLINES 128 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
