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Thu, 23 Apr 2026 16:48:59 -0700 (PDT) Received: from localhost ([2a01:4b00:d036:ae00:e8d7:434e:1f34:2cb6]) by smtp.gmail.com with UTF8SMTPSA id 5b1f17b1804b1-488fb7a0b60sm161135075e9.17.2026.04.23.16.48.59 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 23 Apr 2026 16:48:59 -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 v10 3/4] liveupdate: add LIVEUPDATE_SESSION_GET_NAME ioctl Date: Fri, 24 Apr 2026 00:44:22 +0100 Message-ID: <20260423234753.3873095-4-luca.boccassi@gmail.com> X-Mailer: git-send-email 2.47.3 In-Reply-To: <20260423234753.3873095-1-luca.boccassi@gmail.com> References: <20260423234753.3873095-1-luca.boccassi@gmail.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspam-User: X-Rspamd-Server: rspam01 X-Rspamd-Queue-Id: 8852480009 X-Stat-Signature: c6ina8jkk6nk7di58fh1nt3a1x31bqai X-HE-Tag: 1776988141-455790 X-HE-Meta: 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 9XGrYLku 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 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: 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 Acked-by: Mike Rapoport (Microsoft) --- include/uapi/linux/liveupdate.h | 21 +++++++++++++++++++++ kernel/liveupdate/luo_session.c | 13 +++++++++++++ 2 files changed, 34 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 5e316a4c5d71..0bcf2def074e 100644 --- a/kernel/liveupdate/luo_session.c +++ b/kernel/liveupdate/luo_session.c @@ -289,10 +289,21 @@ 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; + + 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 +330,8 @@ 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