From: "Steven Rostedt (Google)" rostedt@goodmis.org

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 --- kernel/trace/trace.c | 6 ++++++ 1 file changed, 6 insertions(+)

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index 58afc83afc9d..bb5597c6bfc1 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -8334,6 +8334,10 @@ tracing_buffers_splice_read(struct file *file, loff_t *ppos, 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) @@ -9065,6 +9069,8 @@ rb_simple_write(struct file *filp, const char __user *ubuf, 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); }