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| author | Steven Rostedt (Red Hat) <rostedt@goodmis.org> | 2013-03-14 15:03:53 -0400 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2013-04-05 10:16:52 -0700 |
| commit | 396db58dbf922549ccc9c4c779419d9163da3224 (patch) | |
| tree | cda0c2c31b63daf613194ecc197df65893591cd6 /kernel/trace/trace_sched_wakeup.c | |
| parent | b9736c0eed0bfe68c89a269c89c3483d39ea1c83 (diff) | |
| download | kernel_samsung_espresso10-396db58dbf922549ccc9c4c779419d9163da3224.tar.gz kernel_samsung_espresso10-396db58dbf922549ccc9c4c779419d9163da3224.tar.bz2 kernel_samsung_espresso10-396db58dbf922549ccc9c4c779419d9163da3224.zip | |
tracing: Prevent buffer overwrite disabled for latency tracers
commit 613f04a0f51e6e68ac6fe571ab79da3c0a5eb4da upstream.
The latency tracers require the buffers to be in overwrite mode,
otherwise they get screwed up. Force the buffers to stay in overwrite
mode when latency tracers are enabled.
Added a flag_changed() method to the tracer structure to allow
the tracers to see what flags are being changed, and also be able
to prevent the change from happing.
[Backported for 3.4-stable. Re-added current_trace NULL checks; removed
allocated_snapshot field; adapted to tracing_trace_options_write without
trace_set_options.]
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Lingzhu Xiang <lxiang@redhat.com>
Reviewed-by: CAI Qian <caiqian@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'kernel/trace/trace_sched_wakeup.c')
| -rw-r--r-- | kernel/trace/trace_sched_wakeup.c | 18 |
1 files changed, 13 insertions, 5 deletions
diff --git a/kernel/trace/trace_sched_wakeup.c b/kernel/trace/trace_sched_wakeup.c index f029dd4fd2c..1beb25ec5d9 100644 --- a/kernel/trace/trace_sched_wakeup.c +++ b/kernel/trace/trace_sched_wakeup.c @@ -36,7 +36,7 @@ static void __wakeup_reset(struct trace_array *tr); static int wakeup_graph_entry(struct ftrace_graph_ent *trace); static void wakeup_graph_return(struct ftrace_graph_ret *trace); -static int save_lat_flag; +static int save_flags; #define TRACE_DISPLAY_GRAPH 1 @@ -526,8 +526,11 @@ static void stop_wakeup_tracer(struct trace_array *tr) static int __wakeup_tracer_init(struct trace_array *tr) { - save_lat_flag = trace_flags & TRACE_ITER_LATENCY_FMT; - trace_flags |= TRACE_ITER_LATENCY_FMT; + save_flags = trace_flags; + + /* non overwrite screws up the latency tracers */ + set_tracer_flag(TRACE_ITER_OVERWRITE, 1); + set_tracer_flag(TRACE_ITER_LATENCY_FMT, 1); tracing_max_latency = 0; wakeup_trace = tr; @@ -549,12 +552,15 @@ static int wakeup_rt_tracer_init(struct trace_array *tr) static void wakeup_tracer_reset(struct trace_array *tr) { + int lat_flag = save_flags & TRACE_ITER_LATENCY_FMT; + int overwrite_flag = save_flags & TRACE_ITER_OVERWRITE; + stop_wakeup_tracer(tr); /* make sure we put back any tasks we are tracing */ wakeup_reset(tr); - if (!save_lat_flag) - trace_flags &= ~TRACE_ITER_LATENCY_FMT; + set_tracer_flag(TRACE_ITER_LATENCY_FMT, lat_flag); + set_tracer_flag(TRACE_ITER_OVERWRITE, overwrite_flag); } static void wakeup_tracer_start(struct trace_array *tr) @@ -580,6 +586,7 @@ static struct tracer wakeup_tracer __read_mostly = .print_line = wakeup_print_line, .flags = &tracer_flags, .set_flag = wakeup_set_flag, + .flag_changed = trace_keep_overwrite, #ifdef CONFIG_FTRACE_SELFTEST .selftest = trace_selftest_startup_wakeup, #endif @@ -601,6 +608,7 @@ static struct tracer wakeup_rt_tracer __read_mostly = .print_line = wakeup_print_line, .flags = &tracer_flags, .set_flag = wakeup_set_flag, + .flag_changed = trace_keep_overwrite, #ifdef CONFIG_FTRACE_SELFTEST .selftest = trace_selftest_startup_wakeup, #endif |