diff options
| author | Tahsin Erdogan <tahsin@google.com> | 2017-09-17 03:23:48 -0700 |
|---|---|---|
| committer | Sasha Levin <alexander.levin@verizon.com> | 2017-11-04 20:17:51 -0400 |
| commit | 7919ec276cc3846b14ec677905d92a8c78a3d649 (patch) | |
| tree | 9fffb388fd1b79a6e52f8731ae854cdeec2530d8 /kernel | |
| parent | bb8cb63cdb91730943b2682c0fd6c4ec0948127c (diff) | |
tracing: Fix trace_pipe behavior for instance traces
[ Upstream commit 75df6e688ccd517e339a7c422ef7ad73045b18a2 ]
When reading data from trace_pipe, tracing_wait_pipe() performs a
check to see if tracing has been turned off after some data was read.
Currently, this check always looks at global trace state, but it
should be checking the trace instance where trace_pipe is located at.
Because of this bug, cat instances/i1/trace_pipe in the following
script will immediately exit instead of waiting for data:
cd /sys/kernel/debug/tracing
echo 0 > tracing_on
mkdir -p instances/i1
echo 1 > instances/i1/tracing_on
echo 1 > instances/i1/events/sched/sched_process_exec/enable
cat instances/i1/trace_pipe
Link: http://lkml.kernel.org/r/20170917102348.1615-1-tahsin@google.com
Cc: stable@vger.kernel.org
Fixes: 10246fa35d4f ("tracing: give easy way to clear trace buffer")
Signed-off-by: Tahsin Erdogan <tahsin@google.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Sasha Levin <alexander.levin@verizon.com>
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/trace/trace.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index 17213d74540b..760fa813726c 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -4668,7 +4668,7 @@ static int tracing_wait_pipe(struct file *filp) * * iter->pos will be 0 if we haven't read anything. */ - if (!tracing_is_on() && iter->pos) + if (!tracer_tracing_is_on(iter->tr) && iter->pos) break; mutex_unlock(&iter->mutex); |