pid namespaces: make alloc_pid(), free_pid() and put_pid() work with struct upid
Pavel Emelyanov [Fri, 19 Oct 2007 06:40:05 +0000 (23:40 -0700)]
Each struct upid element of struct pid has to be initialized properly, i.e.
its nr mst be allocated from appropriate pidmap and ns set to appropriate
namespace.

When allocating a new pid, we need to know the namespace this pid will live
in, so the additional argument is added to alloc_pid().

On the other hand, the rest of the kernel still uses the pid->nr and
pid->pid_chain fields, so these ones are still initialized, but this will be
removed soon.

Signed-off-by: Pavel Emelyanov <xemul@openvz.org>
Cc: Oleg Nesterov <oleg@tv-sign.ru>
Cc: Sukadev Bhattiprolu <sukadev@us.ibm.com>
Cc: Paul Menage <menage@google.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

include/linux/pid.h
kernel/fork.c
kernel/pid.c

index e5865a9..67470ad 100644 (file)
@@ -111,7 +111,7 @@ extern struct pid *FASTCALL(find_pid(int nr));
 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)
index d2f4a42..984d259 100644 (file)
@@ -1041,7 +1041,7 @@ static struct task_struct *copy_process(unsigned long clone_flags,
                goto bad_fork_cleanup_put_domain;
 
        if (pid != &init_struct_pid) {
-               pid = alloc_pid();
+               pid = alloc_pid(task_active_pid_ns(p));
                if (!pid)
                        goto bad_fork_put_binfmt_module;
        }
index c7346fb..8132a6d 100644 (file)
@@ -29,7 +29,8 @@
 #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;
@@ -186,11 +187,13 @@ 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);
 
@@ -203,45 +206,61 @@ static void delayed_put_pid(struct rcu_head *rhp)
 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);
        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;
+       pid->nr = pid->numbers[0].nr;
        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)]);
+       hlist_add_head_rcu(&pid->pid_chain, &pid_hash[pid_hashfn(pid->nr, 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;
@@ -253,7 +272,7 @@ struct pid * fastcall find_pid(int nr)
        struct pid *pid;
 
        hlist_for_each_entry_rcu(pid, elem,
-                       &pid_hash[pid_hashfn(nr)], pid_chain) {
+                       &pid_hash[pid_hashfn(nr, &init_pid_ns)], pid_chain) {
                if (pid->nr == nr)
                        return pid;
        }