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 280AFC433EF for ; Thu, 13 Jan 2022 08:02:36 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232800AbiAMICf (ORCPT ); Thu, 13 Jan 2022 03:02:35 -0500 Received: from smtp21.cstnet.cn ([159.226.251.21]:43724 "EHLO cstnet.cn" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S231391AbiAMICe (ORCPT ); Thu, 13 Jan 2022 03:02:34 -0500 Received: from localhost.localdomain (unknown [124.16.138.126]) by APP-01 (Coremail) with SMTP id qwCowACXn1d_3N9h7bRFBg--.37830S2; Thu, 13 Jan 2022 16:02:08 +0800 (CST) From: Jiasheng Jiang To: jirislaby@kernel.org, gregkh@linuxfoundation.org Cc: linux-serial@vger.kernel.org, linux-kernel@vger.kernel.org, Jiasheng Jiang Subject: Re: Re: [PATCH] tty/serial: Check for null pointer after calling devm_ioremap Date: Thu, 13 Jan 2022 16:02:06 +0800 Message-Id: <20220113080206.1198250-1-jiasheng@iscas.ac.cn> X-Mailer: git-send-email 2.25.1 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-CM-TRANSID: qwCowACXn1d_3N9h7bRFBg--.37830S2 X-Coremail-Antispam: 1UD129KBjvdXoW7Wr43KryUGw47tr15Xw43Wrg_yoWDGwb_WF s8Can3Z34rAr1rta1qkry3Zw4aqrsI9ayxWr1xZF9Fy3s8ZFs7WFZrurn7Zw4UXws2qF1D Gr47Zw4UZF4jvjkaLaAFLSUrUUUUUb8apTn2vfkv8UJUUUU8Yxn0WfASr-VFAUDa7-sFnT 9fnUUIcSsGvfJTRUUUbckFF20E14v26r1j6r4UM7CY07I20VC2zVCF04k26cxKx2IYs7xG 6rWj6s0DM7CIcVAFz4kK6r1j6r18M28lY4IEw2IIxxk0rwA2F7IY1VAKz4vEj48ve4kI8w A2z4x0Y4vE2Ix0cI8IcVAFwI0_Xr0_Ar1l84ACjcxK6xIIjxv20xvEc7CjxVAFwI0_Gr0_ Cr1l84ACjcxK6I8E87Iv67AKxVWxJr0_GcWl84ACjcxK6I8E87Iv6xkF7I0E14v26rxl6s 0DM2AIxVAIcxkEcVAq07x20xvEncxIr21l5I8CrVACY4xI64kE6c02F40Ex7xfMcIj6xII jxv20xvE14v26r1j6r18McIj6I8E87Iv67AKxVWUJVW8JwAm72CE4IkC6x0Yz7v_Jr0_Gr 1lF7xvr2IYc2Ij64vIr41lF7I21c0EjII2zVCS5cI20VAGYxC7MxkIecxEwVAFwVW8ZwCF 04k20xvY0x0EwIxGrwCFx2IqxVCFs4IE7xkEbVWUJVW8JwC20s026c02F40E14v26r1j6r 18MI8I3I0E7480Y4vE14v26r106r1rMI8E67AF67kF1VAFwI0_JF0_Jw1lIxkGc2Ij64vI r41lIxAIcVC0I7IYx2IY67AKxVWUJVWUCwCI42IY6xIIjxv20xvEc7CjxVAFwI0_Jr0_Gr 1lIxAIcVCF04k26cxKx2IYs7xG6rWUJVWrZr1UMIIF0xvEx4A2jsIE14v26r1j6r4UMIIF 0xvEx4A2jsIEc7CjxVAFwI0_Gr0_Gr1UYxBIdaVFxhVjvjDU0xZFpf9x0JUIzuXUUUUU= X-Originating-IP: [124.16.138.126] X-CM-SenderInfo: pmld2xxhqjqxpvfd2hldfou0/ Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Jan 13, 2022 at 03:35:14PM +0800, Jiri Slaby wrote: >> diff --git a/drivers/tty/serial/milbeaut_usio.c b/drivers/tty/serial/milbeaut_usio.c >> index 8f2cab7f66ad..1ecbf6d0dc79 100644 >> --- a/drivers/tty/serial/milbeaut_usio.c >> +++ b/drivers/tty/serial/milbeaut_usio.c >> @@ -523,6 +523,10 @@ static int mlb_usio_probe(struct platform_device *pdev) >> } >> port->membase = devm_ioremap(&pdev->dev, res->start, >> resource_size(res)); >> + if (!port->membase) { >> + ret = -ENOMEM; >> + goto failed; >> + } > > what about using devm_ioremap_resource() and have only one if there? Well, I check the comment of the devm_ioremap_resource() and notice that it checks and requests region before ioremap. And the usage example is fit for the situation. But I have still have no idea what the concrete advantages of the devm_ioremap_resource(), like fixing something or improve the efficiency. Please give me more detail. Sincerely thanks, Jiang