From: "Steven Rostedt (Google)" <rostedt@goodmis.org>
Date: Wed, 28 Sep 2022 18:22:20 -0400
Subject: tracing: Wake up waiters when tracing is disabled
Git-commit: 2b0fd9a59b7990c161fa1cb7b79edb22847c87c2
Patch-mainline: v6.1-rc1
References: git-fixes
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>
Acked-by: Petr Pavlu <petr.pavlu@suse.com>
---
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);
}