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 CDED11A5D7F; Fri, 29 Mar 2024 12:47:33 +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=1711716453; cv=none; b=umSM+1WCyiBxbFgk6gMKHU8kHFW6BGwAEDQHCLXsjMbgjZAwUt9yYQEXIHJhO6tXC7uX101hISLBOVuu9d7s2aQpbd95ci+wFQ0f8Geo4uxo4V2biNBUdAx6GsOxR8OlX8O9a6onFdaMTmnc0wBf9/6uPM9XQUaUrXSnlgU9rR8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1711716453; c=relaxed/simple; bh=/mV5g2u4Bgi3sJcKcC/duOfJ8yg/8UzMmXb6B1zUg2A=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=qsqXANjWCWVbKauEP3hEzP09J4g8Pp5PDKbGB0WIQF3sxxBmOk/vE/8rbQEE37+88AMWsvr7VTjQRVYzXWwm+X49JJB9WAx9G+sS6i8d5U1rCT73XqDEacKt1Jjp0ECcUTX6nZ45yOqYkJrHWpk4mYd2MqEFAYc0PsCq7Qpm49s= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=NjMNluy3; 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="NjMNluy3" Received: by smtp.kernel.org (Postfix) with ESMTPSA id B8640C433A6; Fri, 29 Mar 2024 12:47:32 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1711716453; bh=/mV5g2u4Bgi3sJcKcC/duOfJ8yg/8UzMmXb6B1zUg2A=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=NjMNluy3d7NUA4pQVabD7zH6NDiqg6NQGA751XNQxFs/fDKhPYsdLcoyH2jXA2OwO XCHxkTnTJRuCm2MZp5GFCVci9XjdggJNLOG09exBYaJ7x0nZOw+BqKH6g72Tm2y9cJ mTbgfcG58KuaRaRKxh3IYC74SBRsYaopKh66gohXGDt6u+V+eNd+O2R1N1zwZ47aZ1 iiBvxSkkQ1qd3OGDxHSrV9tAmijHbpMqoenWkLhTPMZLVLUcbF76M2I5FxSufGu1Qy 0JlbROIYLTmOCg1pCsHSC2+ps22D65T1f6c/JMACPFhzMkYmUZUNv35LSACCTw7DI3 FAdKTHA3NttoA== 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 6.1 52/52] ring-buffer: use READ_ONCE() to read cpu_buffer->commit_page in concurrent environment Date: Fri, 29 Mar 2024 08:45:46 -0400 Message-ID: <20240329124605.3091273-52-sashal@kernel.org> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20240329124605.3091273-1-sashal@kernel.org> References: <20240329124605.3091273-1-sashal@kernel.org> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore X-stable-base: Linux 6.1.83 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 e019a9278794f..7ed92f311dc9b 100644 --- a/kernel/trace/ring_buffer.c +++ b/kernel/trace/ring_buffer.c @@ -4384,7 +4384,7 @@ 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