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| author | Steven Rostedt (Red Hat) <rostedt@goodmis.org> | 2013-07-23 22:21:59 -0400 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2013-08-04 16:50:44 +0800 |
| commit | c62771c88704f0814d0fead60eadc0397a5e832f (patch) | |
| tree | b0d6fedaa94d8f56ff69227236edde8c74ded190 | |
| parent | e55679914313bbfc003dcdf8ff74a16dec2fe24d (diff) | |
| download | kernel-common-c62771c88704f0814d0fead60eadc0397a5e832f.tar.gz kernel-common-c62771c88704f0814d0fead60eadc0397a5e832f.tar.bz2 kernel-common-c62771c88704f0814d0fead60eadc0397a5e832f.zip | |
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>
| -rw-r--r-- | kernel/trace/trace.c | 3 |
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 |