From mboxrd@z Thu Jan 1 00:00:00 1970 From: akpm@linux-foundation.org Subject: [patch 1/1] proc connector: add event for process becoming session leader Date: Thu, 06 Aug 2009 16:05:47 -0700 Message-ID: <200908062305.n76N5lZj005259@imap1.linux-foundation.org> Cc: netdev@vger.kernel.org, akpm@linux-foundation.org, scott@ubuntu.com, johnpol@2ka.mipt.ru, matthltc@us.ibm.com, oleg@tv-sign.ru To: davem@davemloft.net Return-path: Received: from smtp1.linux-foundation.org ([140.211.169.13]:59456 "EHLO smtp1.linux-foundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756867AbZHFXGq (ORCPT ); Thu, 6 Aug 2009 19:06:46 -0400 Sender: netdev-owner@vger.kernel.org List-ID: From: Scott James Remnant The act of a process becoming a session leader is a useful signal to a supervising init daemon such as Upstart. While a daemon will normally do this as part of the process of becoming a daemon, it is rare for its children to do so. When the children do, it is nearly always a sign that the child should be considered detached from the parent and not supervised along with it. The poster-child example is OpenSSH; the per-login children call setsid() so that they may control the pty connected to them. If the primary daemon dies or is restarted, we do not want to consider the per-login children and want to respawn the primary daemon without killing the children. This patch adds a new PROC_SID_EVENT and associated structure to the proc_event event_data union, it arranges for this to be emitted when the special PIDTYPE_SID pid is set. [akpm@linux-foundation.org: coding-style fixes] Signed-off-by: Scott James Remnant Acked-by: Matt Helsley Cc: Oleg Nesterov Cc: Evgeniy Polyakov Cc: "David S. Miller" Signed-off-by: Andrew Morton --- drivers/connector/cn_proc.c | 25 +++++++++++++++++++++++++ include/linux/cn_proc.h | 10 ++++++++++ kernel/exit.c | 4 +++- 3 files changed, 38 insertions(+), 1 deletion(-) diff -puN drivers/connector/cn_proc.c~proc-connector-add-event-for-process-becoming-session-leader drivers/connector/cn_proc.c --- a/drivers/connector/cn_proc.c~proc-connector-add-event-for-process-becoming-session-leader +++ a/drivers/connector/cn_proc.c @@ -139,6 +139,31 @@ void proc_id_connector(struct task_struc cn_netlink_send(msg, CN_IDX_PROC, GFP_KERNEL); } +void proc_sid_connector(struct task_struct *task) +{ + struct cn_msg *msg; + struct proc_event *ev; + struct timespec ts; + __u8 buffer[CN_PROC_MSG_SIZE]; + + if (atomic_read(&proc_event_num_listeners) < 1) + return; + + msg = (struct cn_msg *)buffer; + ev = (struct proc_event *)msg->data; + get_seq(&msg->seq, &ev->cpu); + ktime_get_ts(&ts); /* get high res monotonic timestamp */ + put_unaligned(timespec_to_ns(&ts), (__u64 *)&ev->timestamp_ns); + ev->what = PROC_EVENT_SID; + ev->event_data.sid.process_pid = task->pid; + ev->event_data.sid.process_tgid = task->tgid; + + memcpy(&msg->id, &cn_proc_event_id, sizeof(msg->id)); + msg->ack = 0; /* not used */ + msg->len = sizeof(*ev); + cn_netlink_send(msg, CN_IDX_PROC, GFP_KERNEL); +} + void proc_exit_connector(struct task_struct *task) { struct cn_msg *msg; diff -puN include/linux/cn_proc.h~proc-connector-add-event-for-process-becoming-session-leader include/linux/cn_proc.h --- a/include/linux/cn_proc.h~proc-connector-add-event-for-process-becoming-session-leader +++ a/include/linux/cn_proc.h @@ -52,6 +52,7 @@ struct proc_event { PROC_EVENT_EXEC = 0x00000002, PROC_EVENT_UID = 0x00000004, PROC_EVENT_GID = 0x00000040, + PROC_EVENT_SID = 0x00000080, /* "next" should be 0x00000400 */ /* "last" is the last process event: exit */ PROC_EVENT_EXIT = 0x80000000 @@ -89,6 +90,11 @@ struct proc_event { } e; } id; + struct sid_proc_event { + __kernel_pid_t process_pid; + __kernel_pid_t process_tgid; + } sid; + struct exit_proc_event { __kernel_pid_t process_pid; __kernel_pid_t process_tgid; @@ -102,6 +108,7 @@ struct proc_event { void proc_fork_connector(struct task_struct *task); void proc_exec_connector(struct task_struct *task); void proc_id_connector(struct task_struct *task, int which_id); +void proc_sid_connector(struct task_struct *task); void proc_exit_connector(struct task_struct *task); #else static inline void proc_fork_connector(struct task_struct *task) @@ -114,6 +121,9 @@ static inline void proc_id_connector(str int which_id) {} +static inline void proc_sid_connector(struct task_struct *task) +{} + static inline void proc_exit_connector(struct task_struct *task) {} #endif /* CONFIG_PROC_EVENTS */ diff -puN kernel/exit.c~proc-connector-add-event-for-process-becoming-session-leader kernel/exit.c --- a/kernel/exit.c~proc-connector-add-event-for-process-becoming-session-leader +++ a/kernel/exit.c @@ -359,8 +359,10 @@ void __set_special_pids(struct pid *pid) { struct task_struct *curr = current->group_leader; - if (task_session(curr) != pid) + if (task_session(curr) != pid) { change_pid(curr, PIDTYPE_SID, pid); + proc_sid_connector(curr); + } if (task_pgrp(curr) != pid) change_pid(curr, PIDTYPE_PGID, pid); _