From: Steven Rostedt (Google) rostedt@goodmis.org
commit 2b0fd9a59b7990c161fa1cb7b79edb22847c87c2 upstream.
When tracing is disabled, there's no reason that waiters should stay waiting, wake them up, otherwise tasks get stuck when they should be flushing the buffers.
Cc: stable@vger.kernel.org Fixes: e30f53aad2202 ("tracing: Do not busy wait in buffer splice") Signed-off-by: Steven Rostedt (Google) rostedt@goodmis.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- kernel/trace/trace.c | 6 ++++++ 1 file changed, 6 insertions(+)
--- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -8334,6 +8334,10 @@ tracing_buffers_splice_read(struct file if (ret) goto out;
+ /* No need to wait after waking up when tracing is off */ + if (!tracer_tracing_is_on(iter->tr)) + goto out; + /* Make sure we see the new wait_index */ smp_rmb(); if (wait_index != iter->wait_index) @@ -9043,6 +9047,8 @@ rb_simple_write(struct file *filp, const tracer_tracing_off(tr); if (tr->current_trace->stop) tr->current_trace->stop(tr); + /* Wake up any waiters */ + ring_buffer_wake_waiters(buffer, RING_BUFFER_ALL_CPUS); } mutex_unlock(&trace_types_lock); }