[PATCH] ring-buffer: mark racy accesses on work->wait_index

From: linke li <lilinke99@qq.com>
Cc: lilinke99@qq.com, Steven Rostedt <rostedt@goodmis.org>,
	Masami Hiramatsu <mhiramat@kernel.org>,
	Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
	linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org
Subject: [PATCH] ring-buffer: mark racy accesses on work->wait_index
Date: Wed,  6 Mar 2024 10:55:34 +0800	[thread overview]
Message-ID: <tencent_BA1473492BC618B473864561EA3AB1418908@qq.com> (raw)

Mark data races to work->wait_index as benign using READ_ONCE and WRITE_ONCE. These accesses are expected to be racy.

Signed-off-by: linke li <lilinke99@qq.com>
---
 kernel/trace/ring_buffer.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c
index 0699027b4f4c..a47e9e9750cc 100644
--- a/kernel/trace/ring_buffer.c
+++ b/kernel/trace/ring_buffer.c
@@ -798,7 +798,7 @@ void ring_buffer_wake_waiters(struct trace_buffer *buffer, int cpu)
 		rbwork = &cpu_buffer->irq_work;
 	}
 
-	rbwork->wait_index++;
+	WRITE_ONCE(rbwork->wait_index, READ_ONCE(rbwork->wait_index) + 1);
 	/* make sure the waiters see the new index */
 	smp_wmb();
 
@@ -906,7 +906,7 @@ int ring_buffer_wait(struct trace_buffer *buffer, int cpu, int full)
 
 		/* Make sure to see the new wait index */
 		smp_rmb();
-		if (wait_index != work->wait_index)
+		if (wait_index != READ_ONCE(work->wait_index))
 			break;
 	}
 
-- 
2.39.3 (Apple Git-145)

