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_DFF7D3561A0686B5E8FC07915...
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 1ac6637895a44..0d98e847fd6c2 100644 --- a/kernel/trace/ring_buffer.c +++ b/kernel/trace/ring_buffer.c @@ -4389,7 +4389,7 @@ 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;
/*