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[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-api@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