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: Oleg Nesterov <oleg@tv-sign.ru>
Acked-by: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Pavel Emelyanov <xemul@openvz.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 0 insertions, 1 deletions

diff --git a/init/main.c b/init/main.c
index 9a5b18c0a63d..ed9747f00ec4 100644
--- a/init/main.c
+++ b/init/main.c
@@ -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);