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=-17.5 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,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 2F1B6C636CA for ; Sun, 18 Jul 2021 10:44:37 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 00B9761186 for ; Sun, 18 Jul 2021 10:44:36 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232736AbhGRKrd (ORCPT ); Sun, 18 Jul 2021 06:47:33 -0400 Received: from mail.kernel.org ([198.145.29.99]:59022 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231836AbhGRKrc (ORCPT ); Sun, 18 Jul 2021 06:47:32 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 77A7D6113D; Sun, 18 Jul 2021 10:44:33 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1626605074; bh=iB4eNeNXHNll8Y3BVbUqYop9nEpXbiTMg0YmXxECg8o=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=QPJPApJVh1YrLpjr4XfwBQHxiIjeHYti7s6G1qX3zXx5CPGJ7ZhjwhQT43lqXsLMx tI/rpCsL8+Zdf7/Okm734xvP/BEQCtjkr6LCezCdby16jfKCZkr9MTD3V4BwupYmXn umYehu+63v2hvLGtWN6yOOGmwqSX8X12btY803O3ZEFYQTNuiYLx/+B3OsFIlqehux HmfStzkMhiJzbAwXbD/Sr43ewNhB/x7Q65iUlwrGt3+l3bNH30WW7G/h6mbvYLouyt KZuIMvP1vN/S8R/ZuROGxggFr5Wnd+EqTOuptmPRFro1BZewusxnBNv4ka5v5wgsPm B4AQn/Fi9DXGg== Date: Sun, 18 Jul 2021 13:44:30 +0300 From: Leon Romanovsky To: Xiyu Yang Cc: Raju Rangoju , "David S. Miller" , Jakub Kicinski , netdev@vger.kernel.org, linux-kernel@vger.kernel.org, yuanxzhang@fudan.edu.cn, Xin Tan Subject: Re: [PATCH] cxgb4: Convert from atomic_t to refcount_t on l2t_entry->refcnt Message-ID: References: <1626517014-42631-1-git-send-email-xiyuyang19@fudan.edu.cn> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1626517014-42631-1-git-send-email-xiyuyang19@fudan.edu.cn> Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On Sat, Jul 17, 2021 at 06:16:54PM +0800, Xiyu Yang wrote: > refcount_t type and corresponding API can protect refcounters from > accidental underflow and overflow and further use-after-free situations. > > Signed-off-by: Xiyu Yang > Signed-off-by: Xin Tan > --- > drivers/net/ethernet/chelsio/cxgb4/l2t.c | 31 ++++++++++++++++--------------- > drivers/net/ethernet/chelsio/cxgb4/l2t.h | 3 ++- > 2 files changed, 18 insertions(+), 16 deletions(-) > > diff --git a/drivers/net/ethernet/chelsio/cxgb4/l2t.c b/drivers/net/ethernet/chelsio/cxgb4/l2t.c > index a10a6862a9a4..cb26a5e315b1 100644 > --- a/drivers/net/ethernet/chelsio/cxgb4/l2t.c > +++ b/drivers/net/ethernet/chelsio/cxgb4/l2t.c > @@ -69,7 +69,8 @@ static inline unsigned int vlan_prio(const struct l2t_entry *e) > > static inline void l2t_hold(struct l2t_data *d, struct l2t_entry *e) > { > - if (atomic_add_return(1, &e->refcnt) == 1) /* 0 -> 1 transition */ > + refcount_inc(&e->refcnt); > + if (refcount_read(&e->refcnt) == 1) /* 0 -> 1 transition */ > atomic_dec(&d->nfree); > } > > @@ -270,10 +271,10 @@ static struct l2t_entry *alloc_l2e(struct l2t_data *d) > > /* there's definitely a free entry */ > for (e = d->rover, end = &d->l2tab[d->l2t_size]; e != end; ++e) > - if (atomic_read(&e->refcnt) == 0) > + if (refcount_read(&e->refcnt) == 0) This is wrong. Thanks