Commit 430c6231 authored by Oleg Nesterov's avatar Oleg Nesterov Committed by Linus Torvalds

start the global /sbin/init with 0,0 special pids

As Eric pointed out, there is no problem with init starting with sid == pgid
== 0, and this was historical linux behavior changed in 2.6.18.

Remove kernel_init()->__set_special_pids(), this is unneeded and complicates
the rules for sys_setsid().

This change and the previous change in daemonize() mean that /sbin/init does
not need the special "session != 1" hack in sys_setsid() any longer. We can't
remove this check yet, we should cleanup copy_process(CLONE_NEWPID) first, so
update the comment only.
Signed-off-by: default avatarOleg Nesterov <oleg@tv-sign.ru>
Acked-by: default avatar"Eric W. Biederman" <ebiederm@xmission.com>
Cc: Pavel Emelyanov <xemul@openvz.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 297bd42b
......@@ -833,7 +833,6 @@ static int __init kernel_init(void * unused)
*/
init_pid_ns.child_reaper = current;
__set_special_pids(task_pid(current));
cad_pid = task_pid(current);
smp_prepare_cpus(setup_max_cpus);
......
......@@ -1054,12 +1054,11 @@ asmlinkage long sys_setsid(void)
if (group_leader->signal->leader)
goto out;
/* Fail if a process group id already exists that equals the proposed
* session id.
/* Fail if a process group id already exists that equals the
* proposed session id.
*
* Don't check if session == 1 because kernel threads and CLONE_NEWPID
* tasks use this session id and so the check will always fail and make
* it so init cannot successfully call setsid.
* Don't check if session == 1, clone(CLONE_NEWPID) creates
* this group/session beforehand.
*/
if (session != 1 && pid_task(sid, PIDTYPE_PGID))
goto out;
......
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