From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from fanzine2.igalia.com (fanzine2.igalia.com [213.97.179.56]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 4BAAA37C914; Sun, 24 May 2026 22:40:07 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=213.97.179.56 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779662408; cv=none; b=GTYzAPcJI1CrYmv01bZWyhvkGIbXCB89NkMKuQkWAOuLstehLCmlP2makZkx6D6r2E8aP87A9Qi6yCC0llgYGe33WsxNk64ixKLGQNBGEkQedrIlNoopfvVjGwCcfV3Z+O51ffNviOQ1cvicf5h0JcM5Pu/tj1Y9D/k3TeFmNt0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779662408; c=relaxed/simple; bh=wTGET38CD6COu11C+GfxiQLuwWdWIja53YJgU+fO9Ug=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=oFyEtpjlRRkshbGE0iij0vkXPVFH7ceM5tGl7Xyd3AHgLTy8w6gItSeOK6pUm9ynJyWAKYj2/xw/3Xl/OPFyw8z1mNpjK4tM5orewaF6QmhyiSWKSCaYNIH2BLifERQF3ImQGHKlGxCDG8p3qaN0Ett6QK8tpvgsriii2uylPWs= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=igalia.com; spf=pass smtp.mailfrom=igalia.com; dkim=pass (2048-bit key) header.d=igalia.com header.i=@igalia.com header.b=AeqWbKCO; arc=none smtp.client-ip=213.97.179.56 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=igalia.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=igalia.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=igalia.com header.i=@igalia.com header.b="AeqWbKCO" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=igalia.com; s=20170329; h=Cc:To:In-Reply-To:References:Message-Id: Content-Transfer-Encoding:Content-Type:MIME-Version:Subject:Date:From:Sender: Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From:Resent-Sender :Resent-To:Resent-Cc:Resent-Message-ID:List-Id:List-Help:List-Unsubscribe: List-Subscribe:List-Post:List-Owner:List-Archive; bh=mTm1itVUL5+eVJJJDMx7jNDUCkEzXL7A51fiJoig9I0=; b=AeqWbKCOVKwmpj04OGqNk+lIse OPKs6G1dYVi8+O/iEBzMglZKx/8fvypNTZV+7oqLD1EdlGxOl4VNLAuUvJOLUL7C73cetV7xgTRke yphjQ0hZ9a/e79OWUa2X6Uz679aHPykck+EJdTzN7JkCQ54WpntvzPO8OQXy0Vnk/SQzl4lafJqqB fCUzxlP/hxCP7PiMI+UMtiMMRT0eS8q/8PuFgpnZV5hcbp+Vw/QvHJkxO55AujpaL8RNHyCZ6DC+l AdHQEboVBf7oWmbL3U2cLkLllFjoTAXQFA5Dd6zuSaSPMSJ/dNAvHY8jm9dk5P4rnNHPM9UyjPUqo bB8/wc/Q==; Received: from [179.118.191.12] (helo=[192.168.15.100]) by fanzine2.igalia.com with esmtpsa (Cipher TLS1.3:ECDHE_X25519__RSA_PSS_RSAE_SHA256__AES_256_GCM:256) (Exim) id 1wRHUI-007fJn-7A; Mon, 25 May 2026 00:40:02 +0200 From: =?utf-8?q?Andr=C3=A9_Almeida?= Date: Sun, 24 May 2026 19:38:54 -0300 Subject: [PATCH v2 4/6] sched: Extend task command name to 64 bytes 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: 8bit Message-Id: <20260524-tonyk-long_name-v2-4-332f6bd041c4@igalia.com> References: <20260524-tonyk-long_name-v2-0-332f6bd041c4@igalia.com> In-Reply-To: <20260524-tonyk-long_name-v2-0-332f6bd041c4@igalia.com> To: Peter Zijlstra , Juri Lelli , Vincent Guittot , Steven Rostedt , Christian Brauner , Kees Cook , Shuah Khan , willy@infradead.org, mathieu.desnoyers@efficios.com, David Laight , Linus Torvalds , akpm@linux-foundation.org, Yafang Shao , andrii.nakryiko@gmail.com, arnaldo.melo@gmail.com, Petr Mladek Cc: linux-kernel@vger.kernel.org, kernel-dev@igalia.com, linux-mm@kvack.org, linux-api@vger.kernel.org, Bhupesh , =?utf-8?q?Andr=C3=A9_Almeida?= X-Mailer: b4 0.15.2 Command name has been restrict to only 16 bytes, which is too limiting, specially when debugging and tracing complex software with thousands of threads and the need to differentiate them. Just as it was done with kthreads in commit 6b59808bfe48 ("workqueue: Show the latest workqueue name in /proc/PID/{comm,stat,status}"), support long names for userspace threads as well. To avoid buffer overflows, cap all existing userspace APIs to TASK_COMM_LEN, and leave the full extended name for a new interface. Co-developed-by: Bhupesh Signed-off-by: Bhupesh Signed-off-by: André Almeida --- fs/proc/array.c | 2 +- include/linux/sched.h | 3 ++- kernel/sys.c | 10 +++++----- 3 files changed, 8 insertions(+), 7 deletions(-) diff --git a/fs/proc/array.c b/fs/proc/array.c index c8c3fbd9bfa9..312371eddc7f 100644 --- a/fs/proc/array.c +++ b/fs/proc/array.c @@ -110,7 +110,7 @@ void proc_task_name(struct seq_file *m, struct task_struct *p, bool escape) else if (p->flags & PF_KTHREAD) get_kthread_comm(tcomm, sizeof(tcomm), p); else - strscpy_pad(tcomm, p->comm); + strscpy_pad(tcomm, p->comm, TASK_COMM_LEN); if (escape) seq_escape_str(m, tcomm, ESCAPE_SPACE | ESCAPE_SPECIAL, "\n\\"); diff --git a/include/linux/sched.h b/include/linux/sched.h index b6de742b1155..f7fd2b7d131d 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -323,6 +323,7 @@ struct user_event_mm; */ enum { TASK_COMM_LEN = 16, + TASK_COMM_EXT_LEN = 64, }; extern void sched_tick(void); @@ -1167,7 +1168,7 @@ struct task_struct { * - set it with set_task_comm() to ensure it is always * NUL-terminated and zero-padded */ - char comm[TASK_COMM_LEN]; + char comm[TASK_COMM_EXT_LEN]; struct nameidata *nameidata; diff --git a/kernel/sys.c b/kernel/sys.c index 1d5152d2395e..76d77218ab19 100644 --- a/kernel/sys.c +++ b/kernel/sys.c @@ -2535,7 +2535,7 @@ SYSCALL_DEFINE5(prctl, int, option, unsigned long, arg2, unsigned long, arg3, unsigned long, arg4, unsigned long, arg5) { struct task_struct *me = current; - unsigned char comm[sizeof(me->comm)]; + unsigned char comm[TASK_COMM_LEN]; long error; error = security_task_prctl(option, arg2, arg3, arg4, arg5); @@ -2601,16 +2601,16 @@ SYSCALL_DEFINE5(prctl, int, option, unsigned long, arg2, unsigned long, arg3, error = -EINVAL; break; case PR_SET_NAME: - comm[sizeof(me->comm) - 1] = 0; + comm[TASK_COMM_LEN - 1] = 0; if (strncpy_from_user(comm, (char __user *)arg2, - sizeof(me->comm) - 1) < 0) + TASK_COMM_LEN - 1) < 0) return -EFAULT; set_task_comm(me, comm); proc_comm_connector(me); break; case PR_GET_NAME: - strscpy_pad(comm, me->comm); - if (copy_to_user((char __user *)arg2, comm, sizeof(comm))) + strscpy_pad(comm, me->comm, TASK_COMM_LEN); + if (copy_to_user((char __user *)arg2, comm, TASK_COMM_LEN)) return -EFAULT; break; case PR_GET_ENDIAN: -- 2.54.0