From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id AEEE6199E8E; Fri, 29 Mar 2024 12:42:52 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1711716172; cv=none; b=OsMdZlYDTrWrNm+MPZgRRYi2Lpk+V6/NfYKN3pqed3VMvm3TJV1/CWnfOD4FJpLDF9psVWjhYB4dbonAZSWXV8CsuIfsZ9+oneKDGuFPt5dCPMyBgnK4jCp866kIunWVQ7i2OBFr1+quc1FxkQKvVY586/68N539t2qRxycJDTQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1711716172; c=relaxed/simple; bh=cHQxS9eKOaxd8Sh2UiR3ItlynHa0OS46OHcIPltCVeM=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=ZLx7VOpFGQvkdQ29Eor9H2lnmMSqdEXzA5nW2bLMs+H049N6+2kKjzdK+/pVSSd3EyQ+3RmuXSKHt5B5T6o7Wj14oNDH+DyYRdKkx5pNFisMXFRHIzAZc2LpkzEol2G50Bxzh9ZQTZJzNrZVsetut/Jb0SuqayHSJjWaBZqmze8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=NAKG0q8S; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="NAKG0q8S" Received: by smtp.kernel.org (Postfix) with ESMTPSA id AC108C43399; Fri, 29 Mar 2024 12:42:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1711716172; bh=cHQxS9eKOaxd8Sh2UiR3ItlynHa0OS46OHcIPltCVeM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=NAKG0q8Sjmjfsl+b1D2/nIaVHURz/wo5LLe6LtEuQLxrkZUaivpxqfdXMDhsI18su 3PIe4JpXZ28qu9Ve4nH7sU4oOcgMD0EfpP4mger6C77UV7tOe2uc7uSGZyRfC7pANn AN36698+VQNxxoRfTi3A6KKEH6964g/0rwvKsc4T18Naryv3h3BN9/tHKMi6dhNI9l ns/az+xG5bMVePP+NOXhklUGJOPvADLrRj5i9L7pNvLGPWJIJn9PoMoCboznqTPwUz 1n2QnlSFJr3k735NTlDxDjDOG4urplGFzJUWe3XJ2zrW/JvPlyDL12l8xetasguyg3 UlUeG5hJJIdTg== From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: linke li , Masami Hiramatsu , Mathieu Desnoyers , Steven Rostedt , Sasha Levin , linux-trace-kernel@vger.kernel.org Subject: [PATCH AUTOSEL 6.8 98/98] ring-buffer: use READ_ONCE() to read cpu_buffer->commit_page in concurrent environment Date: Fri, 29 Mar 2024 08:38:09 -0400 Message-ID: <20240329123919.3087149-98-sashal@kernel.org> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20240329123919.3087149-1-sashal@kernel.org> References: <20240329123919.3087149-1-sashal@kernel.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore X-stable-base: Linux 6.8.2 Content-Transfer-Encoding: 8bit From: linke li [ 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 Cc: Mathieu Desnoyers Signed-off-by: linke li Signed-off-by: Steven Rostedt (Google) Signed-off-by: Sasha Levin --- 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 aa332ace108b1..54410c8cacbe8 100644 --- a/kernel/trace/ring_buffer.c +++ b/kernel/trace/ring_buffer.c @@ -4350,7 +4350,7 @@ 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