From 2b0fd9a59b7990c161fa1cb7b79edb22847c87c2 Mon Sep 17 00:00:00 2001 From: "Steven Rostedt (Google)" Date: Wed, 28 Sep 2022 18:22:20 -0400 Subject: [PATCH] tracing: Wake up waiters when tracing is disabled 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) --- 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); }