[RFC][v4][PATCH 4/7]: Add target_pids parameter to alloc_pid()

[Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>]

Subject: [RFC][v4][PATCH 4/7]: Add target_pids parameter to alloc_pid()

This parameter is currently NULL, but will be used in a follow-on patch.

Signed-off-by: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>
Acked-by: Serge Hallyn <serue@us.ibm.com>
Reviewed-by: Oren Laadan <orenl@cs.columbia.edu>
---
 include/linux/pid.h |    2 +-
 kernel/fork.c       |    3 ++-
 kernel/pid.c        |    9 +++++++--
 3 files changed, 10 insertions(+), 4 deletions(-)

Index: linux-2.6/include/linux/pid.h
===================================================================
--- linux-2.6.orig/include/linux/pid.h	2009-08-05 19:34:37.000000000 -0700
+++ linux-2.6/include/linux/pid.h	2009-08-05 19:35:08.000000000 -0700
@@ -119,7 +119,7 @@
 extern struct pid *find_ge_pid(int nr, struct pid_namespace *);
 int next_pidmap(struct pid_namespace *pid_ns, int last);
 
-extern struct pid *alloc_pid(struct pid_namespace *ns);
+extern struct pid *alloc_pid(struct pid_namespace *ns, pid_t *target_pids);
 extern void free_pid(struct pid *pid);
 
 /*
Index: linux-2.6/kernel/fork.c
===================================================================
--- linux-2.6.orig/kernel/fork.c	2009-08-05 19:34:37.000000000 -0700
+++ linux-2.6/kernel/fork.c	2009-08-05 19:35:08.000000000 -0700
@@ -954,6 +954,7 @@
 	int retval;
 	struct task_struct *p;
 	int cgroup_callbacks_done = 0;
+	pid_t *target_pids = NULL;
 
 	if ((clone_flags & (CLONE_NEWNS|CLONE_FS)) == (CLONE_NEWNS|CLONE_FS))
 		return ERR_PTR(-EINVAL);
@@ -1124,7 +1125,7 @@
 		goto bad_fork_cleanup_io;
 
 	if (pid != &init_struct_pid) {
-		pid = alloc_pid(p->nsproxy->pid_ns);
+		pid = alloc_pid(p->nsproxy->pid_ns, target_pids);
 		if (IS_ERR(pid)) {
 			retval = PTR_ERR(pid);
 			goto bad_fork_cleanup_io;
Index: linux-2.6/kernel/pid.c
===================================================================
--- linux-2.6.orig/kernel/pid.c	2009-08-05 19:34:37.000000000 -0700
+++ linux-2.6/kernel/pid.c	2009-08-05 19:35:08.000000000 -0700
@@ -280,13 +280,14 @@
 	call_rcu(&pid->rcu, delayed_put_pid);
 }
 
-struct pid *alloc_pid(struct pid_namespace *ns)
+struct pid *alloc_pid(struct pid_namespace *ns, pid_t *target_pids)
 {
 	struct pid *pid;
 	enum pid_type type;
 	int i, nr;
 	struct pid_namespace *tmp;
 	struct upid *upid;
+	int tpid;
 
 	pid = kmem_cache_alloc(ns->pid_cachep, GFP_KERNEL);
 	if (!pid)
@@ -294,7 +295,11 @@
 
 	tmp = ns;
 	for (i = ns->level; i >= 0; i--) {
-		nr = alloc_pidmap(tmp, 0);
+		tpid = 0;
+		if (target_pids)
+			tpid = target_pids[i];
+
+		nr = alloc_pidmap(tmp, tpid);
 		if (nr < 0)
 			goto out_free;