ring-buffer: use READ_ONCE() to read cpu_buffer->commit_page in concurrent environment
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>
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@ -4382,7 +4382,7 @@ int ring_buffer_iter_empty(struct ring_buffer_iter *iter)
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cpu_buffer = iter->cpu_buffer;
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reader = cpu_buffer->reader_page;
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head_page = cpu_buffer->head_page;
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commit_page = cpu_buffer->commit_page;
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commit_page = READ_ONCE(cpu_buffer->commit_page);
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commit_ts = commit_page->page->time_stamp;
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/*
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