diff options
| author | Tahsin Erdogan <tahsin@google.com> | 2017-09-17 03:23:48 -0700 |
|---|---|---|
| committer | Ben Hutchings <ben@decadent.org.uk> | 2018-01-01 20:51:33 +0000 |
| commit | ffd5ae08fa7174e237f05547aa4ed8a83477b464 (patch) | |
| tree | 4613de65f3f906e0fa389c8f5dc2f6ac145d2b5b /kernel | |
| parent | 8d50600f295857bdc7bf24c27e590b3f05c37afd (diff) | |
tracing: Fix trace_pipe behavior for instance traces
commit 75df6e688ccd517e339a7c422ef7ad73045b18a2 upstream.
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
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: Ben Hutchings <ben@decadent.org.uk>
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 f295d8b8a7cd..99b46db656e0 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -4414,7 +4414,7 @@ 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); |