From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 5EA6DC3279B for ; Fri, 6 Jul 2018 09:48:21 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 0ACD72145B for ; Fri, 6 Jul 2018 09:48:21 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 0ACD72145B Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=huawei.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753713AbeGFJsS (ORCPT ); Fri, 6 Jul 2018 05:48:18 -0400 Received: from szxga06-in.huawei.com ([45.249.212.32]:51815 "EHLO huawei.com" rhost-flags-OK-FAIL-OK-FAIL) by vger.kernel.org with ESMTP id S1753367AbeGFJsQ (ORCPT ); Fri, 6 Jul 2018 05:48:16 -0400 Received: from DGGEMS404-HUB.china.huawei.com (unknown [172.30.72.60]) by Forcepoint Email with ESMTP id 2CAA6BE80DEBD; Fri, 6 Jul 2018 17:48:13 +0800 (CST) Received: from [127.0.0.1] (10.177.16.168) by DGGEMS404-HUB.china.huawei.com (10.3.19.204) with Microsoft SMTP Server id 14.3.382.0; Fri, 6 Jul 2018 17:48:04 +0800 Subject: Re: [PATCH] net/9p/client.c: put refcount of trans_mod in error case in parse_opts() To: piaojun , "akpm@linux-foundation.org" , , , References: <5B3F39A0.2030509@huawei.com> CC: Linux Kernel Mailing List , From: jiangyiwen Message-ID: <5B3F3AD1.9010101@huawei.com> Date: Fri, 6 Jul 2018 17:48:01 +0800 User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:38.0) Gecko/20100101 Thunderbird/38.5.1 MIME-Version: 1.0 In-Reply-To: <5B3F39A0.2030509@huawei.com> Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit X-Originating-IP: [10.177.16.168] X-CFilter-Loop: Reflected Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2018/7/6 17:42, piaojun wrote: >>>From my test, the second mount will fail after umounting successfully. > The reason is that we put refcount of trans_mod in the correct case rather > than the error case in parse_opts() at last. That will cause the refcount > decrease to -1, and when we try to get trans_mod again in > try_module_get(), we could only increase refcount to 0 which will cause > failure as follows: > parse_opts > v9fs_get_trans_by_name > try_module_get : return NULL to caller which cause error > > So we should put refcount of trans_mod in error case. > > Fixes: 9421c3e64137ec ("net/9p/client.c: fix potential refcnt problem of trans module") > > Signed-off-by: Jun Piao It looks good to me. Reviewed-by: Yiwen Jiang > --- > net/9p/client.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/net/9p/client.c b/net/9p/client.c > index 18c5271..5c13431 100644 > --- a/net/9p/client.c > +++ b/net/9p/client.c > @@ -225,7 +225,8 @@ static int parse_opts(char *opts, struct p9_client *clnt) > } > > free_and_return: > - v9fs_put_trans(clnt->trans_mod); > + if (ret) > + v9fs_put_trans(clnt->trans_mod); > kfree(tmp_options); > return ret; > } >