From: Sasha Levin <sashal@kernel.org>
To: linux-kernel@vger.kernel.org, stable@vger.kernel.org
Cc: linke li <lilinke99@qq.com>,
Masami Hiramatsu <mhiramat@kernel.org>,
Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
Steven Rostedt <rostedt@goodmis.org>,
Sasha Levin <sashal@kernel.org>,
linux-trace-kernel@vger.kernel.org
Subject: [PATCH AUTOSEL 6.1 52/52] ring-buffer: use READ_ONCE() to read cpu_buffer->commit_page in concurrent environment
Date: Fri, 29 Mar 2024 08:45:46 -0400 [thread overview]
Message-ID: <20240329124605.3091273-52-sashal@kernel.org> (raw)
In-Reply-To: <20240329124605.3091273-1-sashal@kernel.org>
From: linke li <lilinke99@qq.com>
[ Upstream commit f1e30cb6369251c03f63c564006f96a54197dcc4 ]
In function ring_buffer_iter_empty(), cpu_buffer->commit_page is read
while other threads may change it. It may cause the time_stamp that read
in the next line come from a different page. Use READ_ONCE() to avoid
having to reason about compiler optimizations now and in future.
Link: https://lore.kernel.org/linux-trace-kernel/tencent_DFF7D3561A0686B5E8FC079150A02505180A@qq.com
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: linke li <lilinke99@qq.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
kernel/trace/ring_buffer.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c
index e019a9278794f..7ed92f311dc9b 100644
--- a/kernel/trace/ring_buffer.c
+++ b/kernel/trace/ring_buffer.c
@@ -4384,7 +4384,7 @@ int ring_buffer_iter_empty(struct ring_buffer_iter *iter)
cpu_buffer = iter->cpu_buffer;
reader = cpu_buffer->reader_page;
head_page = cpu_buffer->head_page;
- commit_page = cpu_buffer->commit_page;
+ commit_page = READ_ONCE(cpu_buffer->commit_page);
commit_ts = commit_page->page->time_stamp;
/*
--
2.43.0
parent reply other threads:[~2024-03-29 12:47 UTC|newest]
Thread overview: expand[flat|nested] mbox.gz Atom feed
[parent not found: <20240329124605.3091273-1-sashal@kernel.org>]
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