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=-5.3 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 541C2C38A29 for ; Fri, 10 Apr 2020 08:29:18 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id F1C86207FF for ; Fri, 10 Apr 2020 08:20:31 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=ideasonboard.com header.i=@ideasonboard.com header.b="ewOvNKO6" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1725861AbgDJIUa (ORCPT ); Fri, 10 Apr 2020 04:20:30 -0400 Received: from perceval.ideasonboard.com ([213.167.242.64]:36638 "EHLO perceval.ideasonboard.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725839AbgDJIUa (ORCPT ); Fri, 10 Apr 2020 04:20:30 -0400 Received: from [192.168.0.20] (cpc89242-aztw30-2-0-cust488.18-1.cable.virginm.net [86.31.129.233]) by perceval.ideasonboard.com (Postfix) with ESMTPSA id 0650A329; Fri, 10 Apr 2020 10:20:28 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=ideasonboard.com; s=mail; t=1586506829; bh=roAWbtluHsT87liLV8XRSGZUgZ9inQvmlxDjRpzH7pA=; h=Reply-To:Subject:To:Cc:References:From:Date:In-Reply-To:From; b=ewOvNKO6lbFS9SU0k+0J+bbHBmucg08c5sGX7mDNiClMhQ0ZOasgkBR7byNMcP8PV QD2pWZsaZDrPrC7JBAx3I2exCj/qvSIzwI+iA/KtKW9UBvn3+dkMCaKAY7tyIXQiQ2 RA1RDjTDmLSgW/+19YP8uL/h7XLqqZSC3MgPw0mk= Reply-To: kieran.bingham+renesas@ideasonboard.com Subject: Re: [PATCH v8 02/13] squash! max9286: convert probe kzalloc To: Laurent Pinchart , Sakari Ailus Cc: linux-renesas-soc@vger.kernel.org, Jacopo Mondi , =?UTF-8?Q?Niklas_S=c3=b6derlund?= , Hyun Kwon , Manivannan Sadhasivam References: <20200409121202.11130-1-kieran.bingham+renesas@ideasonboard.com> <20200409121202.11130-3-kieran.bingham+renesas@ideasonboard.com> <20200409163333.GA25086@pendragon.ideasonboard.com> From: Kieran Bingham Organization: Ideas on Board Message-ID: Date: Fri, 10 Apr 2020 09:20:25 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.9.1 MIME-Version: 1.0 In-Reply-To: <20200409163333.GA25086@pendragon.ideasonboard.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-GB Content-Transfer-Encoding: 7bit Sender: linux-renesas-soc-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-renesas-soc@vger.kernel.org Hi Laurent, (+Sakari) On 09/04/2020 17:33, Laurent Pinchart wrote: > Hi Kieran, > > Thank you for the patch. > > On Thu, Apr 09, 2020 at 01:11:51PM +0100, Kieran Bingham wrote: >> v8: >> - Convert probe kzalloc usage to devm_ variant > > This isn't worse than the existing code, but are you aware that devm_* > should not be used in this case ? The memory should be allocated with > kzalloc() and freed in the .release() operation. This change was at the request of a review comment from Sakari. From: https://lore.kernel.org/linux-media/4139f241-2fde-26ad-fe55-dcaeb76ad6cc@ideasonboard.com/ > >>> + >>> +static int max9286_probe(struct i2c_client *client) >>> +{ >>> + struct max9286_priv *priv; >>> + unsigned int i; >>> + int ret; >>> + >>> + priv = kzalloc(sizeof(*priv), GFP_KERNEL); >>> + if (!priv) >>> + return -ENOMEM; >> >> You won't lose anything by using the devm_ variant here. > > Indeed, > >> >>> + >>> + priv->client = client; >>> + i2c_set_clientdata(client, priv); >>> + >>> + for (i = 0; i < MAX9286_N_SINKS; i++) >>> + max9286_init_format(&priv->fmt[i]); >>> + >>> + ret = max9286_parse_dt(priv); >>> + if (ret) >>> + return ret; >> >> But you can avoid accidental memory leaks for nothing. :-) > > It would be good not to leak indeed! I understand that there are lifetime issues in V4L2 - but in my opinion that needs to be handled by core V4l2 (and or support from driver core framework). Also - isn't it highly unlikely to affect the max9286? Isn't the lifetime issue that the device can be unplugged while the file handle is open? I don't think anyone is going to 'unplug' the max9286 while it's active :-) >> --- >> drivers/media/i2c/max9286.c | 5 +---- >> 1 file changed, 1 insertion(+), 4 deletions(-) >> >> diff --git a/drivers/media/i2c/max9286.c b/drivers/media/i2c/max9286.c >> index b84d2daa6561..0a43137b8112 100644 >> --- a/drivers/media/i2c/max9286.c >> +++ b/drivers/media/i2c/max9286.c >> @@ -1155,7 +1155,7 @@ static int max9286_probe(struct i2c_client *client) >> unsigned int i; >> int ret; >> >> - priv = kzalloc(sizeof(*priv), GFP_KERNEL); >> + priv = devm_kzalloc(&client->dev, sizeof(*priv), GFP_KERNEL); >> if (!priv) >> return -ENOMEM; >> >> @@ -1232,7 +1232,6 @@ static int max9286_probe(struct i2c_client *client) >> max9286_configure_i2c(priv, false); >> err_free: >> max9286_cleanup_dt(priv); >> - kfree(priv); >> >> return ret; >> } >> @@ -1253,8 +1252,6 @@ static int max9286_remove(struct i2c_client *client) >> >> gpiod_set_value_cansleep(priv->gpiod_pwdn, 0); >> >> - kfree(priv); >> - >> return 0; >> } >> >