linux-kernel - [PATCH] ring-buffer: mark racy accesses on work->wait

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Date: Wed,  6 Mar 2024 10:55:34 +0800
From: linke li <lilinke99@...com>
To: 
Cc: lilinke99@...com,
	Steven Rostedt <rostedt@...dmis.org>,
	Masami Hiramatsu <mhiramat@...nel.org>,
	Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
	linux-kernel@...r.kernel.org,
	linux-trace-kernel@...r.kernel.org
Subject: [PATCH] ring-buffer: mark racy accesses on work->wait_index

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@...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)