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

init/main.c

+0 −1
Original line number Diff line number Diff line
@@ -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);

kernel/sys.c

+4 −5
Original line number Diff line number Diff line
@@ -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;