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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id C8810C38145 for ; Wed, 7 Sep 2022 12:37:21 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229488AbiIGMhU (ORCPT ); Wed, 7 Sep 2022 08:37:20 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:35026 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229476AbiIGMhT (ORCPT ); Wed, 7 Sep 2022 08:37:19 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A1EC8AF4A5; Wed, 7 Sep 2022 05:37:18 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id 641BEB81C29; Wed, 7 Sep 2022 12:37:17 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id A510EC433D6; Wed, 7 Sep 2022 12:37:15 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1662554236; bh=WIHwNbc9S0mBJ0PzSmdjD+CvPdr06HeB66MNOQMDFlc=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=MlKwNDn3XuQDr8wwMcEZ0F3zU2+TlkRs5xCS5yei0ErirUkCnO61JIJWETVDV1uKR t8wXNmA+M5iD6RbhqEG4UoWQ8a1Qu9trgl1oByGnjvjnX41uGpgHIEAqyJYHBzyZli sj6ycG+/BWbWe91JIUy4xQ1n04teXc9XY05NqQ9qazXsCE+0FVPYz5UL8QxTEqBWFY 4B9kh7CnjWNaEq0Gr2JNW973Jn5OAiPmVDhE5G03TuAgxrjLk6txoYDJXJ/uTxBbCk JdWbA1GrOa1jbPTz5l7yNYng3NCytp4jDibUZgZc28Vy278ZNevATVoce8/lMXVkWQ 3BmKyRGLqmrpg== Date: Wed, 7 Sep 2022 15:37:11 +0300 From: Leon Romanovsky To: Li zeming Cc: jgg@ziepe.ca, linux-rdma@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] rdma/rdmavt_qp: Remove unnecessary 'NULL' values from qp Message-ID: References: <20220907033604.4637-1-zeming@nfschina.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220907033604.4637-1-zeming@nfschina.com> Precedence: bulk List-ID: X-Mailing-List: linux-rdma@vger.kernel.org On Wed, Sep 07, 2022 at 11:36:04AM +0800, Li zeming wrote: > The pointer qp is assigned before it is used, it does not need to be > initialized and assigned. > > Signed-off-by: Li zeming > --- > include/rdma/rdmavt_qp.h | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/include/rdma/rdmavt_qp.h b/include/rdma/rdmavt_qp.h > index 2e58d5e6ac0e..2afc3300d618 100644 > --- a/include/rdma/rdmavt_qp.h > +++ b/include/rdma/rdmavt_qp.h > @@ -699,7 +699,7 @@ static inline struct rvt_qp *rvt_lookup_qpn(struct rvt_dev_info *rdi, > struct rvt_ibport *rvp, > u32 qpn) __must_hold(RCU) > { > - struct rvt_qp *qp = NULL; > + struct rvt_qp *qp; > > if (unlikely(qpn <= 1)) { > qp = rcu_dereference(rvp->qp[qpn]); This function is completely wrong, most likely it never returns NULL otherwise, we would crash in "if (qp->ibqp.qp_num == qpn)" line. The proper change will be something like this: diff --git a/include/rdma/rdmavt_qp.h b/include/rdma/rdmavt_qp.h index 2e58d5e6ac0e..883c328e06b6 100644 --- a/include/rdma/rdmavt_qp.h +++ b/include/rdma/rdmavt_qp.h @@ -699,19 +699,19 @@ static inline struct rvt_qp *rvt_lookup_qpn(struct rvt_dev_info *rdi, struct rvt_ibport *rvp, u32 qpn) __must_hold(RCU) { - struct rvt_qp *qp = NULL; + struct rvt_qp *qp; + u32 n; - if (unlikely(qpn <= 1)) { - qp = rcu_dereference(rvp->qp[qpn]); - } else { - u32 n = hash_32(qpn, rdi->qp_dev->qp_table_bits); + if (unlikely(qpn <= 1)) + return rcu_dereference(rvp->qp[qpn]); - for (qp = rcu_dereference(rdi->qp_dev->qp_table[n]); qp; - qp = rcu_dereference(qp->next)) - if (qp->ibqp.qp_num == qpn) - break; - } - return qp; + n = hash_32(qpn, rdi->qp_dev->qp_table_bits); + + for (qp = rcu_dereference(rdi->qp_dev->qp_table[n]); qp; + qp = rcu_dereference(qp->next)) + if (qp->ibqp.qp_num == qpn) + return qp; + return NULL; } /** > -- > 2.18.2 >