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 25C75C433EF for ; Wed, 9 Mar 2022 17:26:05 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237040AbiCIR1C (ORCPT ); Wed, 9 Mar 2022 12:27:02 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58136 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S237147AbiCIR0z (ORCPT ); Wed, 9 Mar 2022 12:26:55 -0500 Received: from smtp-relay-internal-0.canonical.com (smtp-relay-internal-0.canonical.com [185.125.188.122]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id EFDB3939A1 for ; Wed, 9 Mar 2022 09:25:56 -0800 (PST) Received: from mail-ej1-f70.google.com (mail-ej1-f70.google.com [209.85.218.70]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by smtp-relay-internal-0.canonical.com (Postfix) with ESMTPS id A2F073F79B for ; Wed, 9 Mar 2022 17:25:52 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=canonical.com; s=20210705; t=1646846752; bh=w8PSCKHgDHhX5Fk0xr0ksja4KZOk9BnJpb1vWvY5lY0=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=jVcjgyyR1ErHJvmdajevlKSPULJKAB6Y+cceZ1UVwa051jQtwOPQpFOgo2/chKC6C NcYqRCSnCBnnaUveb/PsphCXKWotiqXU8i9yT+b8tJwbdZW990iJ8FWStFvegIKyWb S8NPh6XRCpNLLUZuCKAMtxrdTPTFkbH9D0OpLY4oZBx8Mbuz2zBm22rHBEvjUXx5VE 5c5WXP05EzH2T4RnHh+kk8753kg1O7sqPxQjHKdk5rXZMV0ozAkzRknEF+gUhLmN3d gnx2iWNX6uZBF+L1wLyLjtYrhQo6pDCyjLP64SXzurpd30pEtOgQ0HZ/10MOBVafYe L9mCSIZwuuzKA== Received: by mail-ej1-f70.google.com with SMTP id l24-20020a170906a41800b006da873d66b6so1666096ejz.3 for ; Wed, 09 Mar 2022 09:25:52 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:message-id:date:mime-version:user-agent:subject :content-language:to:cc:references:from:in-reply-to :content-transfer-encoding; bh=w8PSCKHgDHhX5Fk0xr0ksja4KZOk9BnJpb1vWvY5lY0=; b=54n6XlSCz/XcZ41wS6Hp9Hh6s8jmq/kbQ/tXjWRIOGy6J694jB0RwQHad1OW3f6eDr 01OAeB+EVZXz7fCKo+VgZDy4z8jnMZJX2eSdZckDOu+HW6j3ClNYHKLr+A6WeJgq/JH5 Pa2ohgKYoY+C4rNUIqR/O7fsi2crTIWU9Y2bMl3pcWoI/P+O7ibj+SA4IMK4Gvumxu4G PfciLggYG2iqGBBOgQDnsjKKQsqPMCwQ0jdJ3H/dVH1WumdETARKfICPilApQaNh7seC j7Kr7sxSpBXQdFoGYtl2EVSfVd3YY7tHJ2pPUGosj1ynGa/QGx9lio/kiIPxs+POb5xz G1OQ== X-Gm-Message-State: AOAM5314i3SNyLZB/RiUnoXmPM3Q3vVbh6gcX/o9yJ/rbryV/5UMROhu oCzk93PsqW7y6jkYxNcRMJdcJO++4Cdi2Cb3Alqh6oYf5ToEPz5D3LtXszg19mFUG9FYhnZPTNy E6bkYAvK6jLWMzwqkNaaoFkq08ZMvKrf6r2ovfBTtPQ== X-Received: by 2002:a17:906:c1d6:b0:6d6:e0a3:bbc7 with SMTP id bw22-20020a170906c1d600b006d6e0a3bbc7mr776332ejb.484.1646846750459; Wed, 09 Mar 2022 09:25:50 -0800 (PST) X-Google-Smtp-Source: ABdhPJz6x1VsSMjgBumRVLSBZgLWkRJGulfHwx4sCPHBQhOxMdDxarTS5BRj0fuRAdgAZPDfSlJmjg== X-Received: by 2002:a17:906:c1d6:b0:6d6:e0a3:bbc7 with SMTP id bw22-20020a170906c1d600b006d6e0a3bbc7mr776305ejb.484.1646846750255; Wed, 09 Mar 2022 09:25:50 -0800 (PST) Received: from [192.168.0.144] (xdsl-188-155-174-239.adslplus.ch. [188.155.174.239]) by smtp.gmail.com with ESMTPSA id o2-20020a50d802000000b00410d7f0c52csm1103696edj.8.2022.03.09.09.25.49 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 09 Mar 2022 09:25:49 -0800 (PST) Message-ID: Date: Wed, 9 Mar 2022 18:25:48 +0100 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.5.0 Subject: Re: [PATCH v2 14/26] usb: gadget: s3c-hsudc: remove usage of list iterator past the loop body Content-Language: en-US To: Jakob Koschel , Greg Kroah-Hartman Cc: linux-kernel@vger.kernel.org, Linus Torvalds , Felipe Balbi , Joel Stanley , Andrew Jeffery , Nicolas Ferre , Alexandre Belloni , Claudiu Beznea , Cristian Birsan , Al Cooper , Li Yang , Vladimir Zapolskiy , Daniel Mack , Haojian Zhuang , Robert Jarzmik , Alim Akhtar , Thierry Reding , Jonathan Hunter , Michal Simek , "open list:USB GADGET/PERIPHERAL SUBSYSTEM" , Mike Rapoport , Brian Johannesmeyer , Cristiano Giuffrida , "Bos, H.J." References: <20220308171818.384491-1-jakobkoschel@gmail.com> <20220308171818.384491-15-jakobkoschel@gmail.com> From: Krzysztof Kozlowski In-Reply-To: <20220308171818.384491-15-jakobkoschel@gmail.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 08/03/2022 18:18, Jakob Koschel wrote: > If the list representing the request queue does not contain the expected > request, the value of the list_for_each_entry() iterator will not point > to a valid structure. To avoid type confusion in such case, the list > iterator scope will be limited to the list_for_each_entry() loop. > > In preparation to limiting scope of the list iterator to the list traversal > loop, use a dedicated pointer to point to the found request object [1]. > > Link: https://lore.kernel.org/all/YhdfEIwI4EdtHdym@kroah.com/ > Signed-off-by: Jakob Koschel > --- > drivers/usb/gadget/udc/s3c-hsudc.c | 12 +++++++----- > 1 file changed, 7 insertions(+), 5 deletions(-) > > diff --git a/drivers/usb/gadget/udc/s3c-hsudc.c b/drivers/usb/gadget/udc/s3c-hsudc.c > index 89f1f8c9f02e..bf803e013458 100644 > --- a/drivers/usb/gadget/udc/s3c-hsudc.c > +++ b/drivers/usb/gadget/udc/s3c-hsudc.c > @@ -877,7 +877,7 @@ static int s3c_hsudc_dequeue(struct usb_ep *_ep, struct usb_request *_req) > { > struct s3c_hsudc_ep *hsep = our_ep(_ep); > struct s3c_hsudc *hsudc = hsep->dev; > - struct s3c_hsudc_req *hsreq; > + struct s3c_hsudc_req *hsreq = NULL, *iter; > unsigned long flags; > > hsep = our_ep(_ep); > @@ -886,11 +886,13 @@ static int s3c_hsudc_dequeue(struct usb_ep *_ep, struct usb_request *_req) > > spin_lock_irqsave(&hsudc->lock, flags); > > - list_for_each_entry(hsreq, &hsep->queue, queue) { > - if (&hsreq->req == _req) > - break; > + list_for_each_entry(iter, &hsep->queue, queue) { > + if (&iter->req != _req) > + continue; > + hsreq = iter; > + break; You have in the loop both continue and break, looks a bit complicated. Why not simpler: if (&iter->req == _req) { hsreq = iter; break; } ? Less code, typical (expected) code flow when looking for something in the list. Is your approach related to some speculative execution? > } > - if (&hsreq->req != _req) { > + if (!hsreq) { > spin_unlock_irqrestore(&hsudc->lock, flags); > return -EINVAL; > } Best regards, Krzysztof