From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-wm1-f48.google.com (mail-wm1-f48.google.com [209.85.128.48]) (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 0764A3B47D2 for ; Wed, 29 Apr 2026 21:22:31 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.128.48 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1777497753; cv=none; b=BMS2P6LKFTB+3aikbEz8gnz+9JSHljkYwfLshFcORmgiAqgCNLlW4TkeZvKNfeiSicNMODXBeCz0wN+obie3fkSGrG86ocIQBMa9wBW+uQ/g83oLkx7036iTvzyqY3WOm0TPhaaoLZLp3f/t8ZIEmmaSYKZVA+FLNhwI9i8wCMc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1777497753; c=relaxed/simple; bh=Rf4dN8sazCWYOCcQUVj2ZL8YR18IuaGIuAR2l/M81co=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=brzqnHQFUqJZ0w34T30+SDgzAUtTo0AU8ubqzm50vieOkZi8hC9l5Jpa1EOPZldWm8I68qM2LpUPH5TIa04TcDwRXmT6d7zSzFH/K+D1n9E2zbeND9n309WdgPelCWAhkz2k5lSrWzZZxsOZGroDqKDFCz9y2eIr4+YBy1dooGU= 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=Auq0N8AS; arc=none smtp.client-ip=209.85.128.48 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="Auq0N8AS" Received: by mail-wm1-f48.google.com with SMTP id 5b1f17b1804b1-48896199cbaso1836955e9.1 for ; Wed, 29 Apr 2026 14:22:31 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20251104; t=1777497750; x=1778102550; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to; bh=Xc2oiP7pp0P8+LSVJw9z98TCpWpEve1jI7g9J2HlvNI=; b=Auq0N8ASOm0fZemlwgbD16aPu5ysR8zn9uHiz8Ba1qJa1ifVlhAFpPKxQWStC2QBCC vSu0R5BlfK3qHaNxnWpmkSqe6a8w4NtGe+7LmAWA+7CpLtuNW2kJocBC4YhpDW7A/3Qa 7VK6/A1W5rI17kG+RCMO+TJLo8NP2S6X7cyLMxHL/RQNfmv5qSchuPGCxARHqJYCCGso uUFUM4abeplEQyO+yc4c/eI2r5PNcU3Q0yAAP5td+wZhwH4jupKfL54/y1k9toE16rfU 7Jy1WgmQ/yudpRSQitkYoeqgnPUAJYz8M9ijy/15QypjNN2rNUJDZd2jeToXEtn4wXEf twyQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1777497750; x=1778102550; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-gg:x-gm-message-state:from :to:cc:subject:date:message-id:reply-to; bh=Xc2oiP7pp0P8+LSVJw9z98TCpWpEve1jI7g9J2HlvNI=; b=CjB5SKxP04xI9WH9LHdKEJ5OgixDl5ZgFSAVsTYckC4GS+QhSeCYKR/3p5IEZc0rb2 PIJGqnLTi0/1+mAg/Xs6EI1leJynWHMUQOLUTOL1FTf/FGghmMRy4vRiXK8uQNO+z47b sVlrz4FZwyUMj0W7s2s7MiTAK9SDmN5+EEc2eMZXsg4zW6BzAko7zjwCUSH1PByNSyTf vYi7dyapetx0b8BV1CVb3k1iEIOYuaQLbExhtwqDxxK9X6gWQy9e40RA0p7woxNge+wC F9jelITWmcTuEwogu8VkwPkU3TErTC57EOEvaku2huu02rBuPCneaJAaF1GDnV4S4HxH ODzQ== X-Forwarded-Encrypted: i=1; AFNElJ/IgFPS6Ugt7V/QJZzU3svsuZ5IVhuyOLBds9Bu4R8sPuckZUJ9esqisbyUHijycI3YYqsxRahhSihnY38=@vger.kernel.org X-Gm-Message-State: AOJu0Yxg5Lrl7iMk+i4B9v5njdhHxLd4XPYWgm0ZfYwjOO23AHIz82Q6 MhrNA8Hru+5TZUJ43D4zORjwHKPZ2PlXQJ8CvICYkidXQui7XKPJnihX X-Gm-Gg: AeBDieuNMw4u1wLNjg40w6auMEQse+EPupYEQ+yvZxbYwsXCvoPYxX/Pm7xcLHn1A4p XhHTckuFckwLMw9yBJ+fejkY5PbE//RKpsTvB/a0gawUo3qWymsNfx4n6+QN3JvijMKP3afGlpb FU83lkcHzlRfw1lJPjC95ovH9WetYr9zBapzLZC/OVOFZPDHYPhG4V65M8OFV/RMgHyBdaBSdcr boi/34lBOHEg2AgEA/NSLPZOpujXMNQJbjjkW1tBlCjz5lT7vMYREtuKMnJJLCAHXF20pHZiinI T7UZBjRE7J6fYzVUfov9SvlYZ0NP7dvI/7sttS8tpqIh09KYnW1xp8HgYk8WVhgte/vVUGT/i14 +GyaOgQRs2zlmI0ClOMYkTvjuzZ4EomSaChFdIpI1Q5derJQqvI9I78iydjMA097tMZAF9fnX27 6Yy28baTjJpKd3DmpV7I090W0D12G6bW9H6ObmFkM= X-Received: by 2002:a05:600c:19c9:b0:48a:7a10:4f17 with SMTP id 5b1f17b1804b1-48a83d66b9emr4530045e9.6.1777497750288; Wed, 29 Apr 2026 14:22:30 -0700 (PDT) Received: from localhost ([2a01:4b00:d036:ae00:8fc7:44bf:8aca:ebae]) by smtp.gmail.com with UTF8SMTPSA id 5b1f17b1804b1-48a822d4b57sm45365325e9.15.2026.04.29.14.22.29 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 29 Apr 2026 14:22:29 -0700 (PDT) From: luca.boccassi@gmail.com To: kexec@lists.infradead.org Cc: linux-mm@kvack.org, rppt@kernel.org, pasha.tatashin@soleen.com, pratyush@kernel.org, linux-kernel@vger.kernel.org, Luca Boccassi Subject: [PATCH v11 3/4] liveupdate: add LIVEUPDATE_SESSION_GET_NAME ioctl Date: Wed, 29 Apr 2026 22:21:16 +0100 Message-ID: <20260429212221.814107-4-luca.boccassi@gmail.com> X-Mailer: git-send-email 2.47.3 In-Reply-To: <20260429212221.814107-1-luca.boccassi@gmail.com> References: <20260429212221.814107-1-luca.boccassi@gmail.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Luca Boccassi Userspace when requesting a session via the ioctl specifies a name and gets a FD, but then there is no ioctl to go back the other way and get the name given a LUO session FD. This is problematic especially when there is a userspace orchestrator that wants to check what FDs it is handling for clients without having to do manual string scraping of procfs, or without procfs at all. Add a ioctl to simply get the name from an FD. Signed-off-by: Luca Boccassi Reviewed-by: Pasha Tatashin Reviewed-by: Pratyush Yadav --- include/uapi/linux/liveupdate.h | 21 +++++++++++++++++++++ kernel/liveupdate/luo_session.c | 16 ++++++++++++++++ 2 files changed, 37 insertions(+) diff --git a/include/uapi/linux/liveupdate.h b/include/uapi/linux/liveupdate.h index 30bc66ee9436..3a9ff53b02e0 100644 --- a/include/uapi/linux/liveupdate.h +++ b/include/uapi/linux/liveupdate.h @@ -59,6 +59,7 @@ enum { LIVEUPDATE_CMD_SESSION_PRESERVE_FD = LIVEUPDATE_CMD_SESSION_BASE, LIVEUPDATE_CMD_SESSION_RETRIEVE_FD = 0x41, LIVEUPDATE_CMD_SESSION_FINISH = 0x42, + LIVEUPDATE_CMD_SESSION_GET_NAME = 0x43, }; /** @@ -213,4 +214,24 @@ struct liveupdate_session_finish { #define LIVEUPDATE_SESSION_FINISH \ _IO(LIVEUPDATE_IOCTL_TYPE, LIVEUPDATE_CMD_SESSION_FINISH) +/** + * struct liveupdate_session_get_name - ioctl(LIVEUPDATE_SESSION_GET_NAME) + * @size: Input; sizeof(struct liveupdate_session_get_name) + * @reserved: Input; Must be zero. Reserved for future use. + * @name: Output; A null-terminated string with the full session name. + * + * Retrieves the full name of the session associated with this file descriptor. + * This is useful because the kernel may truncate the name shown in /proc. + * + * Return: 0 on success, negative error code on failure. + */ +struct liveupdate_session_get_name { + __u32 size; + __u32 reserved; + __u8 name[LIVEUPDATE_SESSION_NAME_LENGTH]; +}; + +#define LIVEUPDATE_SESSION_GET_NAME \ + _IO(LIVEUPDATE_IOCTL_TYPE, LIVEUPDATE_CMD_SESSION_GET_NAME) + #endif /* _UAPI_LIVEUPDATE_H */ diff --git a/kernel/liveupdate/luo_session.c b/kernel/liveupdate/luo_session.c index 24b4f381d3c8..1caaa7886ec6 100644 --- a/kernel/liveupdate/luo_session.c +++ b/kernel/liveupdate/luo_session.c @@ -289,10 +289,24 @@ static int luo_session_finish(struct luo_session *session, return luo_ucmd_respond(ucmd, sizeof(*argp)); } +static int luo_session_get_name(struct luo_session *session, + struct luo_ucmd *ucmd) +{ + struct liveupdate_session_get_name *argp = ucmd->cmd; + + if (argp->reserved != 0) + return -EINVAL; + + strscpy((char *)argp->name, session->name, sizeof(argp->name)); + + return luo_ucmd_respond(ucmd, sizeof(*argp)); +} + union ucmd_buffer { struct liveupdate_session_finish finish; struct liveupdate_session_preserve_fd preserve; struct liveupdate_session_retrieve_fd retrieve; + struct liveupdate_session_get_name get_name; }; struct luo_ioctl_op { @@ -319,6 +333,8 @@ static const struct luo_ioctl_op luo_session_ioctl_ops[] = { struct liveupdate_session_preserve_fd, token), IOCTL_OP(LIVEUPDATE_SESSION_RETRIEVE_FD, luo_session_retrieve_fd, struct liveupdate_session_retrieve_fd, token), + IOCTL_OP(LIVEUPDATE_SESSION_GET_NAME, luo_session_get_name, + struct liveupdate_session_get_name, name), }; static long luo_session_ioctl(struct file *filep, unsigned int cmd, -- 2.47.3