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authorSerge E. Hallyn <serue@us.ibm.com>2007-10-19 02:39:52 -0400
committerLinus Torvalds <torvalds@woody.linux-foundation.org>2007-10-19 14:53:37 -0400
commitb460cbc581a53cc088ceba80608021dd49c63c43 (patch)
tree83c28d0adbc15f4157c77b40fa60c40a71cb8673 /kernel/pid.c
parent3743ca05ff464b8a9e345c08a6c9ce30485f9805 (diff)
pid namespaces: define is_global_init() and is_container_init()
is_init() is an ambiguous name for the pid==1 check. Split it into is_global_init() and is_container_init(). A cgroup init has it's tsk->pid == 1. A global init also has it's tsk->pid == 1 and it's active pid namespace is the init_pid_ns. But rather than check the active pid namespace, compare the task structure with 'init_pid_ns.child_reaper', which is initialized during boot to the /sbin/init process and never changes. Changelog: 2.6.22-rc4-mm2-pidns1: - Use 'init_pid_ns.child_reaper' to determine if a given task is the global init (/sbin/init) process. This would improve performance and remove dependence on the task_pid(). 2.6.21-mm2-pidns2: - [Sukadev Bhattiprolu] Changed is_container_init() calls in {powerpc, ppc,avr32}/traps.c for the _exception() call to is_global_init(). This way, we kill only the cgroup if the cgroup's init has a bug rather than force a kernel panic. [akpm@linux-foundation.org: fix comment] [sukadev@us.ibm.com: Use is_global_init() in arch/m32r/mm/fault.c] [bunk@stusta.de: kernel/pid.c: remove unused exports] [sukadev@us.ibm.com: Fix capability.c to work with threaded init] Signed-off-by: Serge E. Hallyn <serue@us.ibm.com> Signed-off-by: Sukadev Bhattiprolu <sukadev@us.ibm.com> Acked-by: Pavel Emelianov <xemul@openvz.org> Cc: Eric W. Biederman <ebiederm@xmission.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Herbert Poetzel <herbert@13thfloor.at> Cc: Kirill Korotaev <dev@sw.ru> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'kernel/pid.c')
-rw-r--r--kernel/pid.c5
1 files changed, 5 insertions, 0 deletions
diff --git a/kernel/pid.c b/kernel/pid.c
index 78c0dbffde65..bb0785109d39 100644
--- a/kernel/pid.c
+++ b/kernel/pid.c
@@ -70,6 +70,11 @@ struct pid_namespace init_pid_ns = {
70 .child_reaper = &init_task 70 .child_reaper = &init_task
71}; 71};
72 72
73int is_global_init(struct task_struct *tsk)
74{
75 return tsk == init_pid_ns.child_reaper;
76}
77
73/* 78/*
74 * Note: disable interrupts while the pidmap_lock is held as an 79 * Note: disable interrupts while the pidmap_lock is held as an
75 * interrupt might come in and do read_lock(&tasklist_lock). 80 * interrupt might come in and do read_lock(&tasklist_lock).