[PATCH 20/28] [FLAT 5/6] Flat model pid manipulations

[Pavel Emelianov]

The alloc_pid(), free_pid() and put_pid() implementation for flat
model (see [PREP 10/14]). This model allocates ids from two maps and 
hashes the pid in two tables.

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

---

 pid.c |   99 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 files changed, 99 insertions(+)

--- ./kernel/pid.c.flatcore	2007-06-15 15:14:33.000000000 +0400
+++ ./kernel/pid.c	2007-06-15 15:26:23.000000000 +0400
@@ -64,6 +64,12 @@ static inline int mk_pid(struct pid_name
 static struct hlist_head *pid_hash2;
 #define pid_ehashfn(nr, ns) hash_long((unsigned long)nr + (unsigned long)ns, \
 					pidhash_shift)
+
+#ifdef CONFIG_PID_NS_FLAT
+/* flat model uses the second hash to find the pids by their virtual nrs */
+#define vpid_hash	pid_hash2
+#define vpid_hashfn	pid_ehashfn
+#endif
 #endif
 
 /*
@@ -233,6 +239,99 @@ struct pid * fastcall find_pid_ns(int nr
 	return NULL;
 }
 #else
+#ifdef CONFIG_PID_NS_FLAT
+static inline int alloc_pid_nrs(struct pid *pid)
+{
+	int nr, vnr;
+	struct pid_namespace *ns;
+
+	vnr = nr = alloc_pidmap(&init_pid_ns);
+	if (nr < 0)
+		goto out;
+
+	ns = current->nsproxy->pid_ns;
+	/*
+	 * pids in init namespace have both nr and vnr equal
+	 * pids in subnamespace hold the namespace
+	 */
+	if (ns != &init_pid_ns) {
+		vnr = alloc_pidmap(ns);
+		if (vnr < 0)
+			goto out_vnr;
+
+		get_pid_ns(ns);
+	}
+
+	pid->nr = nr;
+	pid->vnr = vnr;
+	pid->ns = ns;
+	spin_lock_irq(&pidmap_lock);
+	hlist_add_head_rcu(&pid->pid_chain, &pid_hash[pid_hashfn(nr)]);
+	if (ns != &init_pid_ns)
+		hlist_add_head_rcu(&pid->vpid_chain,
+				&vpid_hash[vpid_hashfn(vnr, ns)]);
+	spin_unlock_irq(&pidmap_lock);
+	return 0;
+
+out_vnr:
+	free_pidmap(&init_pid_ns, nr);
+out:
+	return vnr;
+}
+
+static inline void unhash_pid_nrs(struct pid *pid)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&pidmap_lock, flags);
+	hlist_del_rcu(&pid->pid_chain);
+	if (pid->ns != &init_pid_ns)
+		hlist_del_rcu(&pid->vpid_chain);
+	spin_unlock_irqrestore(&pidmap_lock, flags);
+
+	free_pidmap(&init_pid_ns, pid->nr);
+	if (pid->ns != &init_pid_ns)
+		free_pidmap(pid->ns, pid->vnr);
+}
+
+static inline void free_pid_nrs(struct pid *pid)
+{
+	if (pid->ns != &init_pid_ns)
+		put_pid_ns(pid->ns);
+}
+
+static inline struct pid *find_global_pid(int nr)
+{
+	struct pid *pid;
+	struct hlist_node *elem;
+
+	hlist_for_each_entry_rcu(pid, elem,
+			&pid_hash[pid_hashfn(nr)], pid_chain) {
+		if (pid->nr == nr)
+			return pid;
+	}
+	return NULL;
+}
+
+static inline struct pid *find_virtual_pid(int nr, struct pid_namespace *ns)
+{
+	struct pid *pid;
+	struct hlist_node *elem;
+
+	hlist_for_each_entry_rcu(pid, elem,
+			&vpid_hash[vpid_hashfn(nr, ns)], vpid_chain) {
+		if (pid->vnr == nr && pid->ns == ns)
+			return pid;
+	}
+	return NULL;
+}
+
+struct pid * fastcall find_pid_ns(int nr, struct pid_namespace *ns)
+{
+	return (ns == &init_pid_ns ?
+			find_global_pid(nr) : find_virtual_pid(nr, ns));
+}
+#endif
 #endif
 
 EXPORT_SYMBOL_GPL(find_pid_ns);