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 9827B21C177; Fri, 29 Mar 2024 12:45:43 +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=1711716343; cv=none; b=oAvFc3gKPN3//xWXjDagKiVMBkUBGZtHunLtPg/BLXloxReu3RZH82f9OUjWdO0NhQUm/5QaQZJiHoq6WnCIOXDjcBE+y5VIrlAgJ4/r3i9gu58BFcoYlXYDtLN9PmHdtWaJPP/Olwm8xKsqsrxPWSGTJG5ZetRsBebp2fx4YAo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1711716343; c=relaxed/simple; bh=S7tMWHWPalm7jOEL4BvFLD+RrDQ085rm20ckplEMUdQ=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=UMoy172OrAnFcHvtJTaG97X+ltjOu7B2Nzij0WkAiay9KN8/3jJ+sWAbsYsPHdgS4Gr0d7GbHfL7lvUBz4xDVl7cTaqDsO04Kbc0VnbD2CHyFdt/HaxJshphwpQjP/zBdFKiCOCmgP6vkNqecsPpZAr7PoYIy0kS8UclEuHtNpE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=bmHSoc6C; 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="bmHSoc6C" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 4217DC433F1; Fri, 29 Mar 2024 12:45:42 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1711716343; bh=S7tMWHWPalm7jOEL4BvFLD+RrDQ085rm20ckplEMUdQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=bmHSoc6CSM0/PagqwgDD2HgoOaL9ZYA+s4Sl4njBYGFdbk2EPM6YA93LK7i92k1DE RB5QZYNH+tvgP2KJ7nDi+c58MN0tOjsIDAuZP3UaZdBd6L5uSO/W+KOLHOyGvsa9tg h/f9S3fgmiKcbXlVfhwfCaeBGMm+YDpELIJy3NF5/sRHLO/xP44ZOb19fHlDxL8YjV F/sft7iPRpBQIDHbUkV3AWnid7OdSFwBG4stTfJpdOtH6H5oRtBfD8vCxnJmSyQGl7 bj10fD/NxhWTvGpnxkULxivhuLlYuDaOKyjqdeLdp6qnxcJ+4QKL11MvHXLjBV0d0+ E4jWpTRM8IVGw== 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 6.6 75/75] ring-buffer: use READ_ONCE() to read cpu_buffer->commit_page in concurrent environment Date: Fri, 29 Mar 2024 08:42:56 -0400 Message-ID: <20240329124330.3089520-75-sashal@kernel.org> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20240329124330.3089520-1-sashal@kernel.org> References: <20240329124330.3089520-1-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 6.6.23 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 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; /* -- 2.43.0