korg/linux
0
0
Fork 0
mirror of https://mirrors.bfsu.edu.cn/git/linux.git synced 2024-11-11 12:28:41 +08:00
Code Issues Packages Projects Releases Wiki Activity

pid namespaces: destroy pid namespace on init's death

Browse Source 
Terminate all processes in a namespace when the reaper of the namespace is
exiting.  We do this by walking the pidmap of the namespace and sending
SIGKILL to all processes.

Signed-off-by: Sukadev Bhattiprolu <sukadev@us.ibm.com>
Acked-by: Pavel Emelyanov <xemul@openvz.org>
Cc: Oleg Nesterov <oleg@tv-sign.ru>
Cc: Sukadev Bhattiprolu <sukadev@us.ibm.com>
Cc: Paul Menage <menage@google.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Sukadev Bhattiprolu 2007-10-18 23:40:13 -07:00 committed by Linus Torvalds
parent 0fbc26a6cf
commit 3eb07c8c8a
3 changed files with 65 additions and 1 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
include/linux/pid.h
View File

@ -125,6 +125,7 @@ extern struct pid *find_ge_pid(int nr, struct pid_namespace *);
extern struct pid *alloc_pid(struct pid_namespace *ns);
extern void FASTCALL(free_pid(struct pid *pid));
extern void zap_pid_ns_processes(struct pid_namespace *pid_ns);
/*
* the helpers to get the pid's id seen from different namespaces

27
kernel/exit.c
View File

@ -879,7 +879,32 @@ static inline void exit_child_reaper(struct task_struct *tsk)
if (likely(tsk->group_leader != task_child_reaper(tsk)))
return;
panic("Attempted to kill init!");
if (tsk->nsproxy->pid_ns == &init_pid_ns)
panic("Attempted to kill init!");
/*
* @tsk is the last thread in the 'cgroup-init' and is exiting.
* Terminate all remaining processes in the namespace and reap them
* before exiting @tsk.
*
* Note that @tsk (last thread of cgroup-init) may not necessarily
* be the child-reaper (i.e main thread of cgroup-init) of the
* namespace i.e the child_reaper may have already exited.
*
* Even after a child_reaper exits, we let it inherit orphaned children,
* because, pid_ns->child_reaper remains valid as long as there is
* at least one living sub-thread in the cgroup init.
* This living sub-thread of the cgroup-init will be notified when
* a child inherited by the 'child-reaper' exits (do_notify_parent()
* uses __group_send_sig_info()). Further, when reaping child processes,
* do_wait() iterates over children of all living sub threads.
* i.e even though 'child_reaper' thread is listed as the parent of the
* orphaned children, any living sub-thread in the cgroup-init can
* perform the role of the child_reaper.
*/
zap_pid_ns_processes(tsk->nsproxy->pid_ns);
}
fastcall NORET_TYPE void do_exit(long code)

38
kernel/pid.c
View File

@ -34,6 +34,7 @@
#include <linux/hash.h>
#include <linux/pid_namespace.h>
#include <linux/init_task.h>
#include <linux/syscalls.h>
#define pid_hashfn(nr, ns) \
hash_long((unsigned long)nr + (unsigned long)ns, pidhash_shift)
@ -567,6 +568,43 @@ void free_pid_ns(struct kref *kref)
put_pid_ns(parent);
}
void zap_pid_ns_processes(struct pid_namespace *pid_ns)
{
int nr;
int rc;
/*
* The last thread in the cgroup-init thread group is terminating.
* Find remaining pid_ts in the namespace, signal and wait for them
* to exit.
*
* Note: This signals each threads in the namespace - even those that
* belong to the same thread group, To avoid this, we would have
* to walk the entire tasklist looking a processes in this
* namespace, but that could be unnecessarily expensive if the
* pid namespace has just a few processes. Or we need to
* maintain a tasklist for each pid namespace.
*
*/
read_lock(&tasklist_lock);
nr = next_pidmap(pid_ns, 1);
while (nr > 0) {
kill_proc_info(SIGKILL, SEND_SIG_PRIV, nr);
nr = next_pidmap(pid_ns, nr);
}
read_unlock(&tasklist_lock);
do {
clear_thread_flag(TIF_SIGPENDING);
rc = sys_wait4(-1, NULL, __WALL, NULL);
} while (rc != -ECHILD);
/* Child reaper for the pid namespace is going away */
pid_ns->child_reaper = NULL;
return;
}
/*
* The pid hash table is scaled according to the amount of memory in the
* machine. From a minimum of 16 slots up to 4096 slots at one gigabyte or