From patchwork Sun Jul 26 10:58:28 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Julia Lawall X-Patchwork-Id: 11685681 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id BB300913 for ; Sun, 26 Jul 2020 11:40:17 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id AD46220715 for ; Sun, 26 Jul 2020 11:40:17 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728019AbgGZLjz (ORCPT ); Sun, 26 Jul 2020 07:39:55 -0400 Received: from mail3-relais-sop.national.inria.fr ([192.134.164.104]:32827 "EHLO mail3-relais-sop.national.inria.fr" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727909AbgGZLjy (ORCPT ); Sun, 26 Jul 2020 07:39:54 -0400 X-IronPort-AV: E=Sophos;i="5.75,398,1589234400"; d="scan'208";a="355309545" Received: from palace.rsr.lip6.fr (HELO palace.lip6.fr) ([132.227.105.202]) by mail3-relais-sop.national.inria.fr with ESMTP/TLS/AES256-SHA256; 26 Jul 2020 13:39:47 +0200 From: Julia Lawall To: Mauro Carvalho Chehab Cc: kernel-janitors@vger.kernel.org, linux-media@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH 3/7] [media] cx231xx: drop unnecessary list_empty Date: Sun, 26 Jul 2020 12:58:28 +0200 Message-Id: <1595761112-11003-4-git-send-email-Julia.Lawall@inria.fr> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1595761112-11003-1-git-send-email-Julia.Lawall@inria.fr> References: <1595761112-11003-1-git-send-email-Julia.Lawall@inria.fr> Sender: linux-media-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-media@vger.kernel.org list_for_each_entry is able to handle an empty list. The only effect of avoiding the loop is not initializing the index variable. Drop list_empty tests in cases where these variables are not used. Note that list_for_each_entry is defined in terms of list_first_entry, which indicates that it should not be used on an empty list. But in list_for_each_entry, the element obtained by list_first_entry is not really accessed, only the address of its list_head field is compared to the address of the list head, so the list_first_entry is safe. The semantic patch that makes this change is as follows: (http://coccinelle.lip6.fr/) @@ expression x,e; iterator name list_for_each_entry; statement S; identifier i; @@ -if (!(list_empty(x))) { list_for_each_entry(i,x,...) S - } ... when != i ? i = e Signed-off-by: Julia Lawall --- drivers/media/usb/cx231xx/cx231xx-core.c | 16 ++++++---------- 1 file changed, 6 insertions(+), 10 deletions(-) diff --git a/drivers/media/usb/cx231xx/cx231xx-core.c b/drivers/media/usb/cx231xx/cx231xx-core.c index 982cb56e..05d91ca 100644 --- a/drivers/media/usb/cx231xx/cx231xx-core.c +++ b/drivers/media/usb/cx231xx/cx231xx-core.c @@ -115,11 +115,9 @@ void cx231xx_init_extension(struct cx231xx *dev) struct cx231xx_ops *ops = NULL; mutex_lock(&cx231xx_devlist_mutex); - if (!list_empty(&cx231xx_extension_devlist)) { - list_for_each_entry(ops, &cx231xx_extension_devlist, next) { - if (ops->init) - ops->init(dev); - } + list_for_each_entry(ops, &cx231xx_extension_devlist, next) { + if (ops->init) + ops->init(dev); } mutex_unlock(&cx231xx_devlist_mutex); } @@ -129,11 +127,9 @@ void cx231xx_close_extension(struct cx231xx *dev) struct cx231xx_ops *ops = NULL; mutex_lock(&cx231xx_devlist_mutex); - if (!list_empty(&cx231xx_extension_devlist)) { - list_for_each_entry(ops, &cx231xx_extension_devlist, next) { - if (ops->fini) - ops->fini(dev); - } + list_for_each_entry(ops, &cx231xx_extension_devlist, next) { + if (ops->fini) + ops->fini(dev); } mutex_unlock(&cx231xx_devlist_mutex); }