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authorSteven Rostedt (Red Hat) <rostedt@goodmis.org>2013-07-23 22:21:59 -0400
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2013-08-04 16:50:44 +0800
commitc62771c88704f0814d0fead60eadc0397a5e832f (patch)
treeb0d6fedaa94d8f56ff69227236edde8c74ded190 /kernel
parente55679914313bbfc003dcdf8ff74a16dec2fe24d (diff)
tracing: Remove locking trace_types_lock from tracing_reset_all_online_cpus()
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/51EEC646.7070306@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> Signed-off-by: Steven Rostedt <rostedt@goodmis.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/trace/trace.c3
1 files changed, 1 insertions, 2 deletions
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 073b9e041d32..f7bc3ce6eaf6 100644
--- 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