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authorPavel Emelyanov <xemul@parallels.com>2012-01-12 17:20:27 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2012-01-12 20:13:11 -0800
commitb8f566b04d3cddd192cfd2418ae6d54ac6353792 (patch)
tree32a5bf86548cd43feff4822d800b6a99e157b5d7 /kernel/pid.c
parentf5138e42211d4e8bfbd6ac5b3816348da1533433 (diff)
downloadlinux-b8f566b04d3cddd192cfd2418ae6d54ac6353792.tar.bz2
sysctl: add the kernel.ns_last_pid control
The sysctl works on the current task's pid namespace, getting and setting its last_pid field. Writing is allowed for CAP_SYS_ADMIN-capable tasks thus making it possible to create a task with desired pid value. This ability is required badly for the checkpoint/restore in userspace. This approach suits all the parties for now. Signed-off-by: Pavel Emelyanov <xemul@parallels.com> Acked-by: Tejun Heo <tj@kernel.org> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Cyrill Gorcunov <gorcunov@openvz.org> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Serge Hallyn <serue@us.ibm.com> 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.c4
1 files changed, 3 insertions, 1 deletions
diff --git a/kernel/pid.c b/kernel/pid.c
index fa5f72227e5f..ce8e00deaccb 100644
--- a/kernel/pid.c
+++ b/kernel/pid.c
@@ -137,7 +137,9 @@ static int pid_before(int base, int a, int b)
}
/*
- * We might be racing with someone else trying to set pid_ns->last_pid.
+ * We might be racing with someone else trying to set pid_ns->last_pid
+ * at the pid allocation time (there's also a sysctl for this, but racing
+ * with this one is OK, see comment in kernel/pid_namespace.c about it).
* We want the winner to have the "later" value, because if the
* "earlier" value prevails, then a pid may get reused immediately.
*