From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-oa1-f43.google.com (mail-oa1-f43.google.com [209.85.160.43]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 7E7621E49F; Wed, 3 Jul 2024 21:56:42 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.160.43 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1720043804; cv=none; b=rutQNJmjVlFfyTmORWBAOvISQejSbk+JrLCXyThvcGxDMzW0PSvZ1CsIvStxlEU+AMj+fl5PLzG/yIjK+KmF1QctZH202/0g4bhkT2igHeiIY7TaQNa1Ew4n3rHNDKSfZbQ8CirK8AjX0TLfC5Pe2KaVksqfImvuGvAumN4ErVg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1720043804; c=relaxed/simple; bh=1+YTn3dIOeDJfoLGZQBdtN3XpA+TZgyiDhPfGpaEPOA=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=fO+ab1LC1jIO5L8w8Rrxq7T3tZMWFDvP4bXS7ySMM00lGmFTJxxu/3979ijK/6B6d3x48OBuZUieyXr9vOxeqfKmhNl+x878fdFw22WlM8LgZkF+A0g0Ws2FJwB0XxBApalvFRdwZkA0eT8Vr+CBDpxq12jbcV6Aciehqt5qT74= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=roeck-us.net; spf=pass smtp.mailfrom=gmail.com; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b=Y1dI6i/z; arc=none smtp.client-ip=209.85.160.43 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=roeck-us.net Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="Y1dI6i/z" Received: by mail-oa1-f43.google.com with SMTP id 586e51a60fabf-24c9f6338a4so21404fac.1; Wed, 03 Jul 2024 14:56:42 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1720043801; x=1720648601; darn=vger.kernel.org; h=content-transfer-encoding:in-reply-to:autocrypt:from :content-language:references:cc:to:subject:user-agent:mime-version :date:message-id:sender:from:to:cc:subject:date:message-id:reply-to; bh=NSE/m2zZbakwvs1F6RA5g6uA7BZCRYoaxoKgYZnqXNo=; b=Y1dI6i/zE970c5jGPPY75CP1I2Vrmu4FxuVF9CJ81WnSXUZuQjdOi47ONXw0Gt7dqz 1YEGDo89/LS9UI8rjV3VbGKLQScych9VlTKRgc/zVArEGXDBDrIrHJBESF5DJh9Z6Vju c1GbekDBY7133Q68dUwuNe5F1dcHdeW74qj3tfKw+m12dxkFZApHS8pC7p6GgB8ZY9Tq WpjfilDVLnPlCgBi5H7S1ue1uDhbk/iyrMHVyz9PqBb4s0LL6gH28xsXudBMmYD9Umsz kNaxu6jJzgPpOEJRgB+BAyVF0naN7Gk3wPSF4z8MydgPR8o7C0WjxY1JWgYk7OCSBH5j yg6Q== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1720043801; x=1720648601; h=content-transfer-encoding:in-reply-to:autocrypt:from :content-language:references:cc:to:subject:user-agent:mime-version :date:message-id:sender:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=NSE/m2zZbakwvs1F6RA5g6uA7BZCRYoaxoKgYZnqXNo=; b=QLVAgLwFnmojjMHZD9se/rQvxhtJYnXuy+lD2p4C+mcoJ4+2CQrFJYw+hj0Ckdb6wB 6prsjgvA23s1HGIdxb4DsbozUsQLeyGcvgvJRkBCdJ22CmDap778uISBpaC4RJMS9qwe U5hCNnfa2Alsm5zj7p8oEnQciVFd7W/lis/to+JiRdnQ3Qr0+wN9lSal5dkUPPb2zbAb 8KKrneFZlHEuLh1zdJxZ51nkbJELnNKKIoX+KtNmWXSaNahoKSxvB+5t494KLTh/Eowb CHJN8iCS0rr7E7jSLFCLzUr8CExPqNiDzeOFDBpYMAULPBqm4vLwXgmi1t6efSr65wHd OQlQ== X-Forwarded-Encrypted: i=1; AJvYcCWN5JcttY9vgFob8MC/RHxRDxM4IgtOM392Hua6u152Wy3mVsq2q2+NTKsGkjF0f7UryEKYP9BB1NZczX2iN+vwd+hHQxHpTNDlO8uVLfSo3vYz4ey4yNOG0fn4RhrJiOyOw3qAWa7BJWU= X-Gm-Message-State: AOJu0Yx4vt6tFAd9/f2vr97k4n+b3BfRY/zn9N+KNZFVSOU6GjJEz/uW IakVzW8cvq3OghrczBxqJ8WzrVeMuGKEduEVJFMXDXl/AQoCWw0fZc1pvw== X-Google-Smtp-Source: AGHT+IGw9OpUcJNXsCVQtff2v6e34FGuCuX1fBCIxFSZw2QkQ7Hmnlysak4EvhPR89gY/eE2/cZzXw== X-Received: by 2002:a05:6870:1ec7:b0:25d:dea:456f with SMTP id 586e51a60fabf-25db3640381mr12229317fac.42.1720043801519; Wed, 03 Jul 2024 14:56:41 -0700 (PDT) Received: from ?IPV6:2600:1700:e321:62f0:329c:23ff:fee3:9d7c? ([2600:1700:e321:62f0:329c:23ff:fee3:9d7c]) by smtp.gmail.com with ESMTPSA id d2e1a72fcca58-70801e53b2csm10920990b3a.39.2024.07.03.14.56.40 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 03 Jul 2024 14:56:40 -0700 (PDT) Sender: Guenter Roeck Message-ID: Date: Wed, 3 Jul 2024 14:56:39 -0700 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] hwmon: (dell-smm) Simplify with cleanup.h To: =?UTF-8?Q?Pali_Roh=C3=A1r?= Cc: Krzysztof Kozlowski , Jean Delvare , linux-hwmon@vger.kernel.org, linux-kernel@vger.kernel.org References: <20240703083129.95955-1-krzysztof.kozlowski@linaro.org> <982dc693-dbb2-41a7-ae0d-3b3c05c28117@roeck-us.net> <20240703191641.i5okrz22exrt3mgk@pali> Content-Language: en-US From: Guenter Roeck Autocrypt: addr=linux@roeck-us.net; keydata= xsFNBE6H1WcBEACu6jIcw5kZ5dGeJ7E7B2uweQR/4FGxH10/H1O1+ApmcQ9i87XdZQiB9cpN RYHA7RCEK2dh6dDccykQk3bC90xXMPg+O3R+C/SkwcnUak1UZaeK/SwQbq/t0tkMzYDRxfJ7 nyFiKxUehbNF3r9qlJgPqONwX5vJy4/GvDHdddSCxV41P/ejsZ8PykxyJs98UWhF54tGRWFl 7i1xvaDB9lN5WTLRKSO7wICuLiSz5WZHXMkyF4d+/O5ll7yz/o/JxK5vO/sduYDIlFTvBZDh gzaEtNf5tQjsjG4io8E0Yq0ViobLkS2RTNZT8ICq/Jmvl0SpbHRvYwa2DhNsK0YjHFQBB0FX IdhdUEzNefcNcYvqigJpdICoP2e4yJSyflHFO4dr0OrdnGLe1Zi/8Xo/2+M1dSSEt196rXaC kwu2KgIgmkRBb3cp2vIBBIIowU8W3qC1+w+RdMUrZxKGWJ3juwcgveJlzMpMZNyM1jobSXZ0 VHGMNJ3MwXlrEFPXaYJgibcg6brM6wGfX/LBvc/haWw4yO24lT5eitm4UBdIy9pKkKmHHh7s jfZJkB5fWKVdoCv/omy6UyH6ykLOPFugl+hVL2Prf8xrXuZe1CMS7ID9Lc8FaL1ROIN/W8Vk BIsJMaWOhks//7d92Uf3EArDlDShwR2+D+AMon8NULuLBHiEUQARAQABzTJHdWVudGVyIFJv ZWNrIChMaW51eCBhY2NvdW50KSA8bGludXhAcm9lY2stdXMubmV0PsLBgQQTAQIAKwIbAwYL CQgHAwIGFQgCCQoLBBYCAwECHgECF4ACGQEFAlVcphcFCRmg06EACgkQyx8mb86fmYFg0RAA nzXJzuPkLJaOmSIzPAqqnutACchT/meCOgMEpS5oLf6xn5ySZkl23OxuhpMZTVX+49c9pvBx hpvl5bCWFu5qC1jC2eWRYU+aZZE4sxMaAGeWenQJsiG9lP8wkfCJP3ockNu0ZXXAXwIbY1O1 c+l11zQkZw89zNgWgKobKzrDMBFOYtAh0pAInZ9TSn7oA4Ctejouo5wUugmk8MrDtUVXmEA9 7f9fgKYSwl/H7dfKKsS1bDOpyJlqhEAH94BHJdK/b1tzwJCFAXFhMlmlbYEk8kWjcxQgDWMu GAthQzSuAyhqyZwFcOlMCNbAcTSQawSo3B9yM9mHJne5RrAbVz4TWLnEaX8gA5xK3uCNCeyI sqYuzA4OzcMwnnTASvzsGZoYHTFP3DQwf2nzxD6yBGCfwNGIYfS0i8YN8XcBgEcDFMWpOQhT Pu3HeztMnF3HXrc0t7e5rDW9zCh3k2PA6D2NV4fews9KDFhLlTfCVzf0PS1dRVVWM+4jVl6l HRIAgWp+2/f8dx5vPc4Ycp4IsZN0l1h9uT7qm1KTwz+sSl1zOqKD/BpfGNZfLRRxrXthvvY8 BltcuZ4+PGFTcRkMytUbMDFMF9Cjd2W9dXD35PEtvj8wnEyzIos8bbgtLrGTv/SYhmPpahJA l8hPhYvmAvpOmusUUyB30StsHIU2LLccUPPOwU0ETofVZwEQALlLbQeBDTDbwQYrj0gbx3bq 7kpKABxN2MqeuqGr02DpS9883d/t7ontxasXoEz2GTioevvRmllJlPQERVxM8gQoNg22twF7 pB/zsrIjxkE9heE4wYfN1AyzT+AxgYN6f8hVQ7Nrc9XgZZe+8IkuW/Nf64KzNJXnSH4u6nJM J2+Dt274YoFcXR1nG76Q259mKwzbCukKbd6piL+VsT/qBrLhZe9Ivbjq5WMdkQKnP7gYKCAi pNVJC4enWfivZsYupMd9qn7Uv/oCZDYoBTdMSBUblaLMwlcjnPpOYK5rfHvC4opxl+P/Vzyz 6WC2TLkPtKvYvXmdsI6rnEI4Uucg0Au/Ulg7aqqKhzGPIbVaL+U0Wk82nz6hz+WP2ggTrY1w ZlPlRt8WM9w6WfLf2j+PuGklj37m+KvaOEfLsF1v464dSpy1tQVHhhp8LFTxh/6RWkRIR2uF I4v3Xu/k5D0LhaZHpQ4C+xKsQxpTGuYh2tnRaRL14YMW1dlI3HfeB2gj7Yc8XdHh9vkpPyuT nY/ZsFbnvBtiw7GchKKri2gDhRb2QNNDyBnQn5mRFw7CyuFclAksOdV/sdpQnYlYcRQWOUGY HhQ5eqTRZjm9z+qQe/T0HQpmiPTqQcIaG/edgKVTUjITfA7AJMKLQHgp04Vylb+G6jocnQQX JqvvP09whbqrABEBAAHCwWUEGAECAA8CGwwFAlVcpi8FCRmg08MACgkQyx8mb86fmYHNRQ/+ J0OZsBYP4leJvQF8lx9zif+v4ZY/6C9tTcUv/KNAE5leyrD4IKbnV4PnbrVhjq861it/zRQW cFpWQszZyWRwNPWUUz7ejmm9lAwPbr8xWT4qMSA43VKQ7ZCeTQJ4TC8kjqtcbw41SjkjrcTG wF52zFO4bOWyovVAPncvV9eGA/vtnd3xEZXQiSt91kBSqK28yjxAqK/c3G6i7IX2rg6pzgqh hiH3/1qM2M/LSuqAv0Rwrt/k+pZXE+B4Ud42hwmMr0TfhNxG+X7YKvjKC+SjPjqp0CaztQ0H nsDLSLElVROxCd9m8CAUuHplgmR3seYCOrT4jriMFBtKNPtj2EE4DNV4s7k0Zy+6iRQ8G8ng QjsSqYJx8iAR8JRB7Gm2rQOMv8lSRdjva++GT0VLXtHULdlzg8VjDnFZ3lfz5PWEOeIMk7Rj trjv82EZtrhLuLjHRCaG50OOm0hwPSk1J64R8O3HjSLdertmw7eyAYOo4RuWJguYMg5DRnBk WkRwrSuCn7UG+qVWZeKEsFKFOkynOs3pVbcbq1pxbhk3TRWCGRU5JolI4ohy/7JV1TVbjiDI HP/aVnm6NC8of26P40Pg8EdAhajZnHHjA7FrJXsy3cyIGqvg9os4rNkUWmrCfLLsZDHD8FnU mDW4+i+XlNFUPUYMrIKi9joBhu18ssf5i5Q= In-Reply-To: <20240703191641.i5okrz22exrt3mgk@pali> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit On 7/3/24 12:16, Pali Rohár wrote: > On Wednesday 03 July 2024 11:52:14 Guenter Roeck wrote: >> On 7/3/24 01:31, Krzysztof Kozlowski wrote: >>> Allocate memory, which is being freed at end of the scope, to make the >>> code a bit simpler. >>> >>> Signed-off-by: Krzysztof Kozlowski >>> --- >>> drivers/hwmon/dell-smm-hwmon.c | 7 +++---- >>> 1 file changed, 3 insertions(+), 4 deletions(-) >>> >>> diff --git a/drivers/hwmon/dell-smm-hwmon.c b/drivers/hwmon/dell-smm-hwmon.c >>> index 0362a13f6525..e72e26db6e10 100644 >>> --- a/drivers/hwmon/dell-smm-hwmon.c >>> +++ b/drivers/hwmon/dell-smm-hwmon.c >>> @@ -14,6 +14,7 @@ >>> #include >>> #include >>> +#include >>> #include >>> #include >>> #include >>> @@ -1095,9 +1096,9 @@ static int dell_smm_init_cdev(struct device *dev, u8 fan_num) >>> struct thermal_cooling_device *cdev; >>> struct dell_smm_cooling_data *cdata; >>> int ret = 0; >>> - char *name; >>> - name = kasprintf(GFP_KERNEL, "dell-smm-fan%u", fan_num + 1); >>> + char *name __free(kfree) = kasprintf(GFP_KERNEL, "dell-smm-fan%u", >>> + fan_num + 1); >>> if (!name) >>> return -ENOMEM; >>> @@ -1115,8 +1116,6 @@ static int dell_smm_init_cdev(struct device *dev, u8 fan_num) >>> ret = -ENOMEM; >>> } >>> - kfree(name); >>> - >>> return ret; >>> } >> >> If you really want to clean this up, just use >> char name[32]; >> ... >> snprintf(name, sizeof(name), "dell-smm-fan%u", fan_num + 1); >> >> I don't see the point of all this complexity. >> >> Guenter >> > > Lets first ask a question: And what the problem we are solving there? None. > I do not see any memory leak here, it is neither mentioned in the commit > message. So I think that there is no real problem, and code has just > clear and explicit alloc/free pattern. > Correct. > On the other hand proposed change with __free does not make it simpler. > It has still same complexity, plus magic around. > Again correct. > snprintf with stack allocation at the first glance looks simpler. > > But has a problem that if in future the device name will change then it > would be required also check (and maybe modify) size of stack buffer. In > its usage you are specifying pair which > has size not related to the string. But something more common sense > would be to specify pair <32,"dell-smm-fan%u"> which could say that it > is always maximally 32 (and you can easily check if the string is not > going to be larger). So for long term maintenance this is maybe worse. > Agreed, but I very much prefer that over the complexity introduced with the "free" magic. Unfortunately, once framework code such as the free magic is introduced, it doesn't help to just say "please go away", because people will just keep submitting patches like this one which don't improve the code but still take review time. Guenter