linux-kernel - [PATCH 13/16] Switch to operating with pid

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Message-ID: <468DF907.2060809@openvz.org>
Date:	Fri, 06 Jul 2007 12:10:47 +0400
From:	Pavel Emelianov <xemul@...nvz.org>
To:	Andrew Morton <akpm@...l.org>
CC:	Sukadev Bhattiprolu <sukadev@...ibm.com>,
	Serge Hallyn <serue@...ibm.com>,
	"Eric W. Biederman" <ebiederm@...ssion.com>,
	Linux Containers <containers@...ts.osdl.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Kirill Korotaev <dev@...nvz.org>
Subject: [PATCH 13/16] Switch to operating with pid_numbers instead of pids

Make alloc_pid() initialize pid_numbers and hash them
into the hashtable, not the struct pid itself.

Signed-off-by: Pavel Emelianov <xemul@...nvz.org>

---

 pid.c |   47 +++++++++++++++++++++++++++++++++--------------
 1 files changed, 33 insertions(+), 14 deletions(-)

--- ./kernel/pid.c.ve12	2007-07-05 11:06:41.000000000 +0400
+++ ./kernel/pid.c	2007-07-05 11:08:23.000000000 +0400
@@ -28,8 +28,10 @@
 #include <linux/hash.h>
 #include <linux/pid_namespace.h>
 #include <linux/init_task.h>
+#include <linux/proc_fs.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;
@@ -194,7 +198,7 @@ fastcall void put_pid(struct pid *pid)
 	if (!pid)
 		return;
 
-	ns = pid->numbers[0].ns;
+	ns = pid->numbers[pid->level].ns;
 	if ((atomic_read(&pid->count) == 1) ||
 	     atomic_dec_and_test(&pid->count))
 		kmem_cache_free(ns->pid_cachep, pid);
@@ -210,13 +214,17 @@ 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);
 }
 
@@ -224,30 +232,43 @@ struct pid *alloc_pid(struct pid_namespa
 {
 	struct pid *pid;
 	enum pid_type type;
-	int nr = -1;
+	struct pid_namespace *ns;
+	int i, nr;
 
-	pid = kmem_cache_alloc(init_pid_ns.pid_cachep, GFP_KERNEL);
+	pid = kmem_cache_alloc(pid_ns->pid_cachep, GFP_KERNEL);
 	if (!pid)
 		goto out;
 
-	nr = alloc_pidmap(current->nsproxy->pid_ns);
-	if (nr < 0)
-		goto out_free;
+	ns = pid_ns;
+	for (i = pid_ns->level; i >= 0; i--) {
+		nr = alloc_pidmap(ns);
+		if (nr < 0)
+			goto out_free;
 
+		pid->numbers[i].nr = nr;
+		pid->numbers[i].ns = ns;
+		ns = ns->parent;
+	}
+
+	pid->level = pid_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:
-	kmem_cache_free(init_pid_ns.pid_cachep, pid);
+	for (i++; i <= pid->level; i++)
+		free_pidmap(pid->numbers[i].ns, pid->numbers[i].nr);
+
+	kmem_cache_free(pid_ns->pid_cachep, pid);
 	pid = NULL;
 	goto out;
 }
@@ -258,7 +279,7 @@ struct pid * fastcall find_pid_ns(int nr
 	struct pid_number *pnr;
 
 	hlist_for_each_entry_rcu(pnr, elem,
-			&pid_hash[pid_hashfn(nr)], pid_chain)
+			&pid_hash[pid_hashfn(nr, ns)], pid_chain)
 		if (pnr->nr == nr && pnr->ns == ns)
 			return container_of(pnr, struct pid,
 					numbers[ns->level]);
-
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