Commit b021184e authored by linke li's avatar linke li Committed by sanglipeng1
Browse files

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

stable inclusion
from stable-v5.10.215
commit 91698804bbeed81aa248ba87200d690302d8c73a
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/IAJJ2D

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=91698804bbeed81aa248ba87200d690302d8c73a

--------------------------------

[ 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: default avatarlinke li <lilinke99@qq.com>
Signed-off-by: default avatarSteven Rostedt (Google) <rostedt@goodmis.org>
Signed-off-by: default avatarSasha Levin <sashal@kernel.org>
Signed-off-by: default avatarsanglipeng1 <sanglipeng1@jd.com>
parent 8411eab2

kernel/trace/ring_buffer.c

+1 −1
Original line number Diff line number Diff line
@@ -4220,7 +4220,7 @@ 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;



	/*