From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-wm1-f47.google.com (mail-wm1-f47.google.com [209.85.128.47]) (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 D0B7534A791 for ; Mon, 25 May 2026 10:34:22 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.128.47 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779705264; cv=none; b=MrVGjSciZmWSL8c0POG4KmSI6TKc9IF9mR1M0wVXv7cMsKII5Evh4vqahTJ+1AN9wHhMwFAhKq3JXyalZAr3dY6phvEEV/01NhS2vGRHWKhGF/K8NQIK7yHVV8SsXzmYJP6vKhJHuWR5gDOfFWiMyNFaxRoQZPkS6B/TS90udNs= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779705264; c=relaxed/simple; bh=mb5ZXkGMIgb6DQIaD/P8DOgOOXgzG2RC35+NeGAmz34=; h=Date:From:To:Cc:Subject:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=cnS4Zx3oIxrx0ssogR7iFIF0s9V1M7Q5EEHcwAakpKqy/Qyuz6ge8K2y3LC0NLBcj2JuCda0X6XBQ+5FmPlCSS/BPc4SbMghislKaaxkKOCQiOdNWftqn+rHdj6i51qPMmlcyHONSwnUE08ZNRkS2X14pR14yhBWf+5Rtq/vgoY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b=HnQ4yPWF; arc=none smtp.client-ip=209.85.128.47 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com 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="HnQ4yPWF" Received: by mail-wm1-f47.google.com with SMTP id 5b1f17b1804b1-4904fd4f6aeso18374695e9.2 for ; Mon, 25 May 2026 03:34:22 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20251104; t=1779705261; x=1780310061; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:subject:cc:to:from:date:from:to:cc:subject:date :message-id:reply-to; bh=ANTTltvHrc5c1FeMjZzkkc8QWIGg79MSqFOZN/bt4nE=; b=HnQ4yPWF5LYAnsBODc5Clb7+diRGkGU15T7CYuOSoIcUsV1QC6no8scIi2PZ1N5epC PEtkTCt47xUHj7FZTzjtaRkjWjKOGS/Cbtj8Hu3YMUdWZYpCi2oHH6Wh/kzeXDJ7yjLx VpUCmEL8/vx1EPqaY1uhtqOFQNNPidISG7dOG9dEEQuk/t89BZboxQsXoH6XbDpzMW/5 s+IsBme9WMlnvqllfjHlaacHYGPSTjFmILDXOuU9sQ0rx5Gq4/uzBwA62rPxFJpTI72/ a+SJEZEm3ACLwj82M3vclcB/uXDr9MDZpEOljsSvlhqGHfqQ8TgwXr4q0NV1Gyo94L6F yYIA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1779705261; x=1780310061; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:subject:cc:to:from:date:x-gm-gg:x-gm-message-state:from :to:cc:subject:date:message-id:reply-to; bh=ANTTltvHrc5c1FeMjZzkkc8QWIGg79MSqFOZN/bt4nE=; b=i4TmwwuLdBhyJMEU2M8yJvk0LnwYms9S/ZBm1xwFsA7rSZNvD91vY6GQ+55Mg/SwQ+ +tUaE94xK79t+2w8t/xUrVtIKUcIhEpFbPjJ6izORr/Mm4lENKRZFn6nDVmDVn1hIs6f epLAOfHsXTA5OJMcKET3ruODc3sixPpCBn5yMZ82ctqD838Xpx4jziQ3MOCNxgbQhzka U/B5jGPPUIs+2r1dJaG05cwGus6zwCiJGZbP1dImGUschN9Ltu1uzxAUts09ohIUDCTr xS27jqLvEnHymT59Kh0+fJTH25KMgOyoRvPGzO0ATtW5+kAH+8v4NQdnyJtia3uRFRGz YxKA== X-Forwarded-Encrypted: i=1; AFNElJ/lYV+AzeXqaJc8T4y6J6ugGvm7pFo0omh8FNbZtvReqBNp1srgfreYLmip/hVZoa0hoJPU5gPE784hFG4=@vger.kernel.org X-Gm-Message-State: AOJu0YzHGlD4aw175CyS3t1uiRL1YNzizePwDBLVUxCbMGY5ZDtTAeJo ivQzSEE3aJhz06v+ncGZXuXTPZbSGjwHY5pq+H3JB7eaC/RKMX8k8j/F X-Gm-Gg: Acq92OF+q/gAZB6F51UjhC6kHfTjmW5QDKMjhErZXuuFbiKkrirbNBs8hxDIpZ/k5Li AlV1hONj8NbZ6J8rLcZibBpnerwrVdQxX3H4a97shDf9BSueuojCfoosrkcwDFTIsbXPJoIWvNW V40kcdLTGrgKbnPNZxIGPa1nFeQLb5ByRvJB9E3sonjBDheudnqFZBsZ0g78js3DlFSdYmeL6eI t9eMqat+VcPbGPaqvmJ2rVVwAROPbkojTVuuhT1cFQTRw2KdTWQneUrQBg+AVFXOWr8GCSdLrn9 DvQuPOoWSUu9MUKsPCFSoHwtO6uPm96bfZz0CggLnGDjiN+yKOYhOENf/rtG1ylPDrsPoIihx1+ 6niZgZKKwhjEA30XAX5zbGEUy0QNycIvjW3HSK2U5AJUw5Fp68Uql3IpAk+v2s+dDS0yZKfw5Zu lmwiF0Io3SRrwQ3FYrzXTBbSkeLvYuPdvWCTYI4skc/U6ToaUaYy4V8bf9ImmOqicF X-Received: by 2002:a05:600c:c4a1:b0:48f:e230:2a1e with SMTP id 5b1f17b1804b1-49042ae7881mr243970285e9.33.1779705260735; Mon, 25 May 2026 03:34:20 -0700 (PDT) Received: from pumpkin (82-69-66-36.dsl.in-addr.zen.co.uk. [82.69.66.36]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-45eb6d5e484sm25157564f8f.30.2026.05.25.03.34.20 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 25 May 2026 03:34:20 -0700 (PDT) Date: Mon, 25 May 2026 11:34:18 +0100 From: David Laight To: =?UTF-8?B?QW5kcsOp?= Almeida Cc: Peter Zijlstra , Juri Lelli , Vincent Guittot , Steven Rostedt , Christian Brauner , Kees Cook , Shuah Khan , willy@infradead.org, mathieu.desnoyers@efficios.com, Linus Torvalds , akpm@linux-foundation.org, Yafang Shao , andrii.nakryiko@gmail.com, arnaldo.melo@gmail.com, Petr Mladek , linux-kernel@vger.kernel.org, kernel-dev@igalia.com, linux-mm@kvack.org, linux-api@vger.kernel.org, Bhupesh Subject: Re: [PATCH v2 2/6] treewide: Get rid of get_task_comm() Message-ID: <20260525113418.032bd1d0@pumpkin> In-Reply-To: <20260524-tonyk-long_name-v2-2-332f6bd041c4@igalia.com> References: <20260524-tonyk-long_name-v2-0-332f6bd041c4@igalia.com> <20260524-tonyk-long_name-v2-2-332f6bd041c4@igalia.com> X-Mailer: Claws Mail 4.1.1 (GTK 3.24.38; arm-unknown-linux-gnueabihf) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable On Sun, 24 May 2026 19:38:52 -0300 Andr=C3=A9 Almeida wrote: > Since commit 4cc0473d7754 ("get rid of __get_task_comm()"), > get_task_comm() does just a redundant check for the buffer size and call > strscpy_pad(). Replace get_task_comm() calls with strscpy_pad(), that will > do the right thing if the buffers sizes doesn't match: zero-pad if it's > bigger, and truncate if it's smaller. >=20 > Link: https://lore.kernel.org/lkml/CAHk-=3Dwi5c=3D_-FBGo_88CowJd_F-Gi6Ud9= d=3DTALm65ReN7YjrMw@mail.gmail.com/ > Co-developed-by: Bhupesh > Signed-off-by: Bhupesh > Signed-off-by: Andr=C3=A9 Almeida > --- ...=20 > -/* > - * - Why not use task_lock()? > - * User space can randomly change their names anyway, so locking for r= eaders > - * doesn't make sense. For writers, locking is probably necessary, as = a race > - * condition could lead to long-term mixed results. > - * The logic inside __set_task_comm() ensures that the task comm is > - * always NUL-terminated and zero-padded. Therefore the race condition= between > - * reader and writer is not an issue. > - * > - * - BUILD_BUG_ON() can help prevent the buf from being truncated. > - * Since the callers don't perform any return value checks, this safeg= uard is > - * necessary. > - */ > -#define get_task_comm(buf, tsk) ({ \ > - BUILD_BUG_ON(sizeof(buf) < TASK_COMM_LEN); \ > - strscpy_pad(buf, (tsk)->comm); \ > - buf; \ > -}) > - I don't think it is worth the churn of removing this wrapper. The calls can be optimised based on the knowledge that tsk->com is always '\0' terminated and can be assumed to be padded. (A read mid-update might give an unpadded result, but that doesn't matter because it can only 'leak' part of an old name. -- David