From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Cyrus-Session-Id: sloti22d1t05-218212-1518281654-2-12353991450961807145 X-Sieve: CMU Sieve 3.0 X-Spam-known-sender: no X-Spam-score: 0.0 X-Spam-hits: BAYES_00 -1.9, HEADER_FROM_DIFFERENT_DOMAINS 0.001, RCVD_IN_DNSWL_HI -5, T_RP_MATCHES_RCVD -0.01, LANGUAGES en, BAYES_USED global, SA_VERSION 3.4.0 X-Spam-source: IP='209.132.180.67', Host='vger.kernel.org', Country='US', FromHeader='com', MailFrom='org' X-Spam-charsets: plain='utf-8' X-Resolved-to: greg@kroah.com X-Delivered-to: greg@kroah.com X-Mail-from: stable-owner@vger.kernel.org ARC-Seal: i=1; a=rsa-sha256; cv=none; d=messagingengine.com; s=arctest; t=1518281654; b=MCRGrDZFtSyKEM3kzw3focQumWrEBWYw16iFss1vXZLrMzC tBScf6km9eQeWh0H4+X/kwLzrkTiAPts8uQPmHXNPItQ5xmyjefSN2Tid/Xg92rU mBPuOTIm0roxgqIBI248RtBjXUZ6T+UIKusJaucPCU8iEkj9UC50gZpPVVlKYRSw JHaQ4U1cVpLqHu+bsVZALZJ50+Rp2+jlKGH0+90Mjy8v/bl+1vNM5jOxswEOjBgU 3PIZh4vLGbyjM64V98kSgWjNpCz9lGgvTpGsJ2ECoRz/Nbo9txnw7wr4T/RArBNm 8I1k6NSYKidjeU4GZ1rmls+UL9nO1XgBQqNOBNQ== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d= messagingengine.com; h=subject:to:cc:references:from:message-id :date:mime-version:in-reply-to:content-type :content-transfer-encoding:sender:list-id; s=arctest; t= 1518281654; bh=Haitv3EQtqmHuu+uEV1p9MJzkGfrNnNnNXSaeqji5M8=; b=S Aq3jcXdAZN9rf4ITwHkoJmYdCvcIi5toXgv72O3WwVDVCsLWSfPT+eANpP3HtYdr kTD9Vz3vQ8pIXIICTBwzHcz7awR5AuJw1VNFAMCkHCsW2q3RhEVby93CROTFgOEa gyDbeIsETHfLzae9a8v+7egw4D05zLBLwab5ETN8HUB06lIQALBCiLOZ+LCHGL4m xDih5/gpuIGvU7/q3ra3pIYfLJUVvu7on2sgxqRdXJhe41ERooBUlpQxS+qFiHGJ aI9w6cwmWVtXLNlKt+kcmDSWC8K/cmoUhw+iRwLuKMPjpVy2gVHOKSsPZm6lklwj xWJuX8WiA9iIrIpGz+EsQ== ARC-Authentication-Results: i=1; mx3.messagingengine.com; arc=none (no signatures found); dkim=pass (2048-bit rsa key sha256) header.d=oracle.com header.i=@oracle.com header.b=HC3QcFHS x-bits=2048 x-keytype=rsa x-algorithm=sha256 x-selector=corp-2017-10-26; dmarc=pass (p=none,has-list-id=yes,d=none) header.from=oracle.com; iprev=pass policy.iprev=209.132.180.67 (vger.kernel.org); spf=none smtp.mailfrom=stable-owner@vger.kernel.org smtp.helo=vger.kernel.org; x-aligned-from=fail; x-ptr=pass x-ptr-helo=vger.kernel.org x-ptr-lookup=vger.kernel.org; x-return-mx=pass smtp.domain=vger.kernel.org smtp.result=pass smtp_org.domain=kernel.org smtp_org.result=pass smtp_is_org_domain=no header.domain=oracle.com header.result=pass header_is_org_domain=yes Authentication-Results: mx3.messagingengine.com; arc=none (no signatures found); dkim=pass (2048-bit rsa key sha256) header.d=oracle.com header.i=@oracle.com header.b=HC3QcFHS x-bits=2048 x-keytype=rsa x-algorithm=sha256 x-selector=corp-2017-10-26; dmarc=pass (p=none,has-list-id=yes,d=none) header.from=oracle.com; iprev=pass policy.iprev=209.132.180.67 (vger.kernel.org); spf=none smtp.mailfrom=stable-owner@vger.kernel.org smtp.helo=vger.kernel.org; x-aligned-from=fail; x-ptr=pass x-ptr-helo=vger.kernel.org x-ptr-lookup=vger.kernel.org; x-return-mx=pass smtp.domain=vger.kernel.org smtp.result=pass smtp_org.domain=kernel.org smtp_org.result=pass smtp_is_org_domain=no header.domain=oracle.com header.result=pass header_is_org_domain=yes Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1750909AbeBJQyJ (ORCPT ); Sat, 10 Feb 2018 11:54:09 -0500 Received: from aserp2130.oracle.com ([141.146.126.79]:59722 "EHLO aserp2130.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750857AbeBJQyJ (ORCPT ); Sat, 10 Feb 2018 11:54:09 -0500 Subject: Re: [PATCH 1/2] xen: xenbus_dev_frontend: Fix XS_TRANSACTION_END handling To: Simon Gaiser , xen-devel@lists.xenproject.org Cc: stable@vger.kernel.org, Juergen Gross , linux-kernel@vger.kernel.org References: <20180207222236.7434-1-simon@invisiblethingslab.com> From: Boris Ostrovsky Message-ID: Date: Sat, 10 Feb 2018 11:53:58 -0500 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.6.0 MIME-Version: 1.0 In-Reply-To: <20180207222236.7434-1-simon@invisiblethingslab.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-Proofpoint-Virus-Version: vendor=nai engine=5900 definitions=8801 signatures=668668 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 suspectscore=0 malwarescore=0 phishscore=0 bulkscore=0 spamscore=0 mlxscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1711220000 definitions=main-1802100222 Sender: stable-owner@vger.kernel.org X-Mailing-List: stable@vger.kernel.org X-getmail-retrieved-from-mailbox: INBOX X-Mailing-List: linux-kernel@vger.kernel.org List-ID: On 02/07/2018 05:22 PM, Simon Gaiser wrote: > Commit fd8aa9095a95 ("xen: optimize xenbus driver for multiple > concurrent xenstore accesses") made a subtle change to the semantic of > xenbus_dev_request_and_reply() and xenbus_transaction_end(). > > Before on an error response to XS_TRANSACTION_END > xenbus_dev_request_and_reply() would not decrement the active > transaction counter. But xenbus_transaction_end() has always counted the > transaction as finished regardless of the response. > > The new behavior is that xenbus_dev_request_and_reply() and > xenbus_transaction_end() will always count the transaction as finished > regardless the response code (handled in xs_request_exit()). > > But xenbus_dev_frontend tries to end a transaction on closing of the > device if the XS_TRANSACTION_END failed before. Trying to close the > transaction twice corrupts the reference count. So fix this by also > considering a transaction closed if we have sent XS_TRANSACTION_END once > regardless of the return code. > > Cc: # 4.11 > Fixes: fd8aa9095a95 ("xen: optimize xenbus driver for multiple concurrent xenstore accesses") > Signed-off-by: Simon Gaiser Reviewed-by: Boris Ostrovsky (although I'd prefer Juergen to also take a look at this) > --- > drivers/xen/xenbus/xenbus_dev_frontend.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/xen/xenbus/xenbus_dev_frontend.c b/drivers/xen/xenbus/xenbus_dev_frontend.c > index f3b089b7c0b6..d2edbc79384a 100644 > --- a/drivers/xen/xenbus/xenbus_dev_frontend.c > +++ b/drivers/xen/xenbus/xenbus_dev_frontend.c > @@ -365,7 +365,7 @@ void xenbus_dev_queue_reply(struct xb_req_data *req) > if (WARN_ON(rc)) > goto out; > } > - } else if (req->msg.type == XS_TRANSACTION_END) { > + } else if (req->type == XS_TRANSACTION_END) { > trans = xenbus_get_transaction(u, req->msg.tx_id); > if (WARN_ON(!trans)) > goto out; >