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authorOleg Nesterov <oleg@tv-sign.ru>2006-03-28 16:11:09 -0800
committerLinus Torvalds <torvalds@g5.osdl.org>2006-03-28 18:36:41 -0800
commitc7c6464117a02b0d54feb4ebeca4db70fa493678 (patch)
tree903498de6685d769631edbd7bce7609d07365946
parent73b9ebfe126a4a886ee46cbab637374d7024668a (diff)
[PATCH] pidhash: don't use zero pids
daemonize() calls set_special_pids(1,1), while init and kernel threads spawned from init/main.c:init() run with 0,0 special pids. This patch changes INIT_SIGNALS() so that that they run with ->pgrp == ->session == 1 also. This patch relies on fact that swapper's pid == 1. Now we have no hashed zero pids in pid_hash[]. User-space visibible change is that now /sbin/init runs with (1,1) special pids and becomes a session leader. Quoting Eric W. Biederman: > > daemonize consuming pids (1,1) then consumes pgrp 1. So that when > /sbin/init calls setsid() it thinks /sbin/init is a process group > leader and setsid() fails. So /sbin/init wants pgrp 1 session 1 > but doesn't get it. I am pretty certain daemonize did not exist so > /sbin/init got pgrp 1 session 1 in 2.4. > > That is the bug that is being fixed. > > This patch takes things one step farther and essentially calls > setsid() for pid == 1 before init is execed. That is new behavior > but it cleans up the kernel as we now do not need to support the > case of a process without a process group or a session. > > The only process that could have possibly cared was /sbin/init > and it already calls setsid() because it doesn't want that. > > If this was going to break anything noticeable the change in behavior > from 2.4 to 2.6 would have already done that. Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
-rw-r--r--include/linux/init_task.h2
1 files changed, 2 insertions, 0 deletions
diff --git a/include/linux/init_task.h b/include/linux/init_task.h
index 92146f3b742..41ecbb847f3 100644
--- a/include/linux/init_task.h
+++ b/include/linux/init_task.h
@@ -62,6 +62,8 @@
.posix_timers = LIST_HEAD_INIT(sig.posix_timers), \
.cpu_timers = INIT_CPU_TIMERS(sig.cpu_timers), \
.rlim = INIT_RLIMITS, \
+ .pgrp = 1, \
+ .session = 1, \
}
#define INIT_SIGHAND(sighand) { \