From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out203-205-221-191.mail.qq.com (out203-205-221-191.mail.qq.com [203.205.221.191]) (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 0D7AA63A5; Sun, 25 Feb 2024 03:05:30 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=203.205.221.191 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1708830333; cv=none; b=D/ES1/qeGtRZKxREA7TChSTAn1b2jCKOnFV7CFIPuLnJMKgiCtEAC/dwFBjZ0OAQZzvZ08gTIjT50pftTStYMkLQzoNLZ6MXFc5CAr1De1puqroJozbyHU3dD4rSpnQcNiJZ3EmNrDVc2iuVj9FgPkvWe7QD3jJUxvQ8W+aMr2w= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1708830333; c=relaxed/simple; bh=L20Dun7FleQn4bkO5h+YiLlfoH0K6st2YbTELaAGEqM=; h=Message-ID:From:To:Cc:Subject:Date:In-Reply-To:References: MIME-Version; b=iVm7ZdP0dGWMAWmzMOlGW+ot/FGaXoC3IeLWhOVonQq275X/rbVEpssWPFSxpPpWqE+lSmP8t5f2a6cEy5+kHNQIpx4YvYAqfGmC16+j8jZG9SdxXgmIk0PVH2eG4UJoaes92k7Obrg5po6U/pl5BnWljaF0qkTOYqIizemYUXE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=qq.com; spf=pass smtp.mailfrom=qq.com; dkim=pass (1024-bit key) header.d=qq.com header.i=@qq.com header.b=mk/W/+vb; arc=none smtp.client-ip=203.205.221.191 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=qq.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=qq.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=qq.com header.i=@qq.com header.b="mk/W/+vb" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=qq.com; s=s201512; t=1708830328; bh=HoHJVcHPbLUtsuObsC+KQhu8jDUrXcUZFTBUuEmCeaA=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=mk/W/+vbGbtOzQQN6i5kEQAxaNlNJZ1/n4jYnPCu4GSW0NjfXAuSBUPS61digJoVd JqB3dwpgACXtFeNWeV1rPTTO9426b1GktJlN51qSxDF4CzQNm4tHq8yeCM8b682DNl 0qgnTh2XioMUi1+PtEUT4URIeM5btqD6vjoZnNMI= Received: from localhost.localdomain ([153.3.164.50]) by newxmesmtplogicsvrsza1-0.qq.com (NewEsmtp) with SMTP id 15A1B477; Sun, 25 Feb 2024 11:05:26 +0800 X-QQ-mid: xmsmtpt1708830326tp7ufxdrg Message-ID: X-QQ-XMAILINFO: MmpliBmRb3iCgVxZIjut2UWdWGFmMiPQDVVN+2H3V+OxYT5Nqc+gbRQEf/z8pD 9TWf4TPSWy5Xmdu/12ppK37qbc9/wJ1LqFOKIixGIOr8Fip2tn09TtwYcp35UARxggvJyveKRhXA qlHe+73mDD7q1qknJGDShXFcNbUcBWgRepwawvTaGIRcp9dt2jrYrOMUyBvRp7ajx0F1IGCuW4Zb +h/CweK4mNQXlZ2t6KGOse0OKaCcocegTrjSJS18tAWN/XIHxDnYk+0CgETK+vYmkEBCrWqU9M1C /e9GNcpAsbaX9T+wZF4jCem/XSbAjugQrH2kp4Q5FMDwkV+XKAJotN1SJkxTYnHaxok7AnkuKvcY qRUo+xN/lFq1JuC00khm6P4++pEseQo6/Pfy9gyxTqaPKrmQrk+0YmsDqfpjETsT48QX9CQxphmk /EDI/D03I43Lkv9YnQTEDdq8ldUkJHwq5OFFK7wdie01XzrkXeo5CCiHenXdKnegDZvF4sawuV+2 TxAZRGCr4Kgz3AuX7/HvxZoKEKJsYB7gh8+IGNgXUfHcZhVBWg+B9hf0VBdi0CfNYpIR79thlOl2 sbSJzJ+rgcDFnydIUcpJJu0nrYVg/SyZjcFdMgl7WMeO+R2tQG4yya6F3KsjgeTuW8ehjZgdGGQB +gqb3/b/HM5AxzZ+HzpVfJo3J6l4VEQhh2x/gUOjop38vg6mAVzpVUFwNkR1/j23C7LJ6oGf87ox tLyS6SNAEbaaJoXdOSRHo9+O4xpQCG8U+6O70bD9VT1MzxQd+MhFUqiMmxOz6J4Wt058x9FMRJZn Nv04yR/Bso4LpuXwTwgSj32QWJSV1SPSCiKRmpMgJ8xLmU9jXQMTmsrY7DbGLB48xgZxbMDcbbAL LZHfJEkfOkbG75gNxS74uVSsqra6nYZj3PdCdnwcHvlJIA05Q7Kgx5VMYzSeXfd/OZlmrM9BHb4k PWK/NGIW65EUURpT6ecCqYXf/x0FbJsYTZvQZdoiQHxjsjODJW3PX+mCbYkCDh1fejzaa8PBI= X-QQ-XMRINFO: Mp0Kj//9VHAxr69bL5MkOOs= From: linke li To: Cc: lilinke99@qq.com, Steven Rostedt , Masami Hiramatsu , Mathieu Desnoyers , linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org Subject: [PATCH] ring-buffer: use READ_ONCE() to read cpu_buffer->commit_page in concurrent environment Date: Sun, 25 Feb 2024 11:05:06 +0800 X-OQ-MSGID: <20240225030507.97911-1-lilinke99@qq.com> X-Mailer: git-send-email 2.39.3 (Apple Git-145) In-Reply-To: References: Precedence: bulk X-Mailing-List: linux-trace-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit In function ring_buffer_iter_empty(), cpu_buffer->commit_page and curr_commit_page->page->time_stamp is read using READ_ONCE() in line 4354, 4355 4354 curr_commit_page = READ_ONCE(cpu_buffer->commit_page); 4355 curr_commit_ts = READ_ONCE(curr_commit_page->page->time_stamp); while they are read directly in line 4340, 4341 4340 commit_page = cpu_buffer->commit_page; 4341 commit_ts = commit_page->page->time_stamp; There is patch similar to this. commit c1c0ce31b242 ("r8169: fix the KCSAN reported data-race in rtl_tx() while reading tp->cur_tx") This patch find two read of same variable while one is protected, another is not. And READ_ONCE() is added to protect. Signed-off-by: linke li --- kernel/trace/ring_buffer.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c index 0699027b4f4c..eb3fa629b837 100644 --- a/kernel/trace/ring_buffer.c +++ b/kernel/trace/ring_buffer.c @@ -4337,8 +4337,8 @@ 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_ts = commit_page->page->time_stamp; + commit_page = READ_ONCE(cpu_buffer->commit_page); + commit_ts = READ_ONCE(commit_page->page->time_stamp); /* * When the writer goes across pages, it issues a cmpxchg which -- 2.39.3 (Apple Git-145)