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ring-buffer: use READ_ONCE() to read cpu_buffer->commit_page in concurrent environment 

[ Upstream commit f1e30cb636 ]

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>
This commit is contained in:
linke li 2024-03-02 12:42:21 +08:00 committed by Greg Kroah-Hartman
parent 5e7da5bb2d
commit 1e9f5619d9
1 changed files with 1 additions and 1 deletions
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2
kernel/trace/ring_buffer.c
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@ -4431,7 +4431,7 @@ 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;
/*