From: linke li <lilink...@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_dff7d3561a0686b5e8fc079150a025051...@qq.com Cc: Masami Hiramatsu <mhira...@kernel.org> Cc: Mathieu Desnoyers <mathieu.desnoy...@efficios.com> Signed-off-by: linke li <lilink...@qq.com> Signed-off-by: Steven Rostedt (Google) <rost...@goodmis.org> Signed-off-by: Sasha Levin <sas...@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 4a43b8846b49f..70b6cb6bfb56e 100644 --- a/kernel/trace/ring_buffer.c +++ b/kernel/trace/ring_buffer.c @@ -4184,7 +4184,7 @@ 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
