[Devel] [PATCH 6/15] Make alloc_pid(), free_pid() and put_pid() work with struct upid

Pavel Emelyanov xemul at openvz.org
Thu Jul 26 07:50:22 PDT 2007


Each struct upid element of struct pid has to be initialized properly,
i.e. its nr mst be allocated from appropriate pidmap and it must be
inserted into the hash.

Signed-off-by: Pavel Emelyanov <xemul at openvz.org>

---

 include/linux/pid.h |    2 +-
 kernel/pid.c        |   52 +++++++++++++++++++++++++++++++++++++---------------
 2 files changed, 38 insertions(+), 16 deletions(-)

diff -upr linux-2.6.23-rc1-mm1.orig/include/linux/pid.h linux-2.6.23-rc1-mm1-7/include/linux/pid.h
--- linux-2.6.23-rc1-mm1.orig/include/linux/pid.h	2007-07-26 16:34:45.000000000 +0400
+++ linux-2.6.23-rc1-mm1-7/include/linux/pid.h	2007-07-26 16:36:37.000000000 +0400
@@ -83,7 +92,7 @@ extern void FASTCALL(detach_pid(struct t
 extern struct pid *find_get_pid(int nr);
 extern struct pid *find_ge_pid(int nr);
 
-extern struct pid *alloc_pid(void);
+extern struct pid *alloc_pid(struct pid_namespace *ns);
 extern void FASTCALL(free_pid(struct pid *pid));
 
 static inline pid_t pid_nr(struct pid *pid)
diff -upr linux-2.6.23-rc1-mm1.orig/kernel/pid.c linux-2.6.23-rc1-mm1-7/kernel/pid.c
--- linux-2.6.23-rc1-mm1.orig/kernel/pid.c	2007-07-26 16:34:45.000000000 +0400
+++ linux-2.6.23-rc1-mm1-7/kernel/pid.c	2007-07-26 16:36:37.000000000 +0400
@@ -28,7 +28,8 @@
 #include <linux/pid_namespace.h>
 #include <linux/init_task.h>
 
-#define pid_hashfn(nr) hash_long((unsigned long)nr, pidhash_shift)
+#define pid_hashfn(nr, ns)	\
+	hash_long((unsigned long)nr + (unsigned long)ns, pidhash_shift)
 static struct hlist_head *pid_hash;
 static int pidhash_shift;
 struct pid init_struct_pid = INIT_STRUCT_PID;
@@ -187,11 +202,13 @@ fastcall void put_pid(struct pid *pid)
 	if (!pid)
 		return;
 
-	/* FIXME - this must be the namespace this pid lives in */
-	ns = &init_pid_ns;
+	ns = pid->numbers[pid->level].ns;
 	if ((atomic_read(&pid->count) == 1) ||
-	     atomic_dec_and_test(&pid->count))
+	     atomic_dec_and_test(&pid->count)) {
 		kmem_cache_free(ns->pid_cachep, pid);
+		if (ns != &init_pid_ns)
+			put_pid_ns(ns);
+	}
 }
 EXPORT_SYMBOL_GPL(put_pid);
 
@@ -204,45 +221,64 @@ static void delayed_put_pid(struct rcu_h
 fastcall void free_pid(struct pid *pid)
 {
 	/* We can be called with write_lock_irq(&tasklist_lock) held */
+	int i;
 	unsigned long flags;
 
 	spin_lock_irqsave(&pidmap_lock, flags);
-	hlist_del_rcu(&pid->pid_chain);
+	for (i = 0; i <= pid->level; i++)
+		hlist_del_rcu(&pid->numbers[i].pid_chain);
 	spin_unlock_irqrestore(&pidmap_lock, flags);
 
-	free_pidmap(&init_pid_ns, pid->nr);
+	for (i = 0; i <= pid->level; i++)
+		free_pidmap(pid->numbers[i].ns, pid->numbers[i].nr);
+
 	call_rcu(&pid->rcu, delayed_put_pid);
 }
 
-struct pid *alloc_pid(void)
+struct pid *alloc_pid(struct pid_namespace *ns)
 {
 	struct pid *pid;
 	enum pid_type type;
-	int nr = -1;
-	struct pid_namespace *ns;
+	int i, nr;
+	struct pid_namespace *tmp;
 
-	ns = task_active_pid_ns(current);
 	pid = kmem_cache_alloc(ns->pid_cachep, GFP_KERNEL);
 	if (!pid)
 		goto out;
 
-	nr = alloc_pidmap(ns);
-	if (nr < 0)
-		goto out_free;
+	tmp = ns;
+	for (i = ns->level; i >= 0; i--) {
+		nr = alloc_pidmap(tmp);
+		if (nr < 0)
+			goto out_free;
+
+		pid->numbers[i].nr = nr;
+		pid->numbers[i].ns = tmp;
+		tmp = tmp->parent;
+	}
 
+	if (ns != &init_pid_ns)
+		get_pid_ns(ns);
+
+	pid->level = ns->level;
 	atomic_set(&pid->count, 1);
-	pid->nr = nr;
 	for (type = 0; type < PIDTYPE_MAX; ++type)
 		INIT_HLIST_HEAD(&pid->tasks[type]);
 
 	spin_lock_irq(&pidmap_lock);
-	hlist_add_head_rcu(&pid->pid_chain, &pid_hash[pid_hashfn(pid->nr)]);
+	for (i = pid->level; i >= 0; i--)
+		hlist_add_head_rcu(&pid->numbers[i].pid_chain,
+				&pid_hash[pid_hashfn(pid->numbers[i].nr,
+					pid->numbers[i].ns)]);
 	spin_unlock_irq(&pidmap_lock);
 
 out:
 	return pid;
 
 out_free:
+	for (i++; i <= ns->level; i++)
+		free_pidmap(pid->numbers[i].ns, pid->numbers[i].nr);
+
 	kmem_cache_free(ns->pid_cachep, pid);
 	pid = NULL;
 	goto out;




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