pid namespaces: prepare proc_flust_task() to flush entries from multiple proc trees

[~andy/linux] / kernel / pid.c

diff --git a/kernel/pid.c b/kernel/pid.c
index eb66bd2953ab95f614781b12da75b4613ec0f757..bb0785109d39998c63ec881bb4f92fed69efaa87 100644 (file)
--- a/kernel/pid.c
+++ b/kernel/pid.c
@@ -32,7 +32,6 @@
 #define pid_hashfn(nr) hash_long((unsigned long)nr, pidhash_shift)
 static struct hlist_head *pid_hash;
 static int pidhash_shift;
-static struct kmem_cache *pid_cachep;
 struct pid init_struct_pid = INIT_STRUCT_PID;
 
 int pid_max = PID_MAX_DEFAULT;
@@ -71,6 +70,11 @@ struct pid_namespace init_pid_ns = {
        .child_reaper = &init_task
 };
 
+int is_global_init(struct task_struct *tsk)
+{
+       return tsk == init_pid_ns.child_reaper;
+}
+
 /*
  * Note: disable interrupts while the pidmap_lock is held as an
  * interrupt might come in and do read_lock(&tasklist_lock).
@@ -176,11 +180,16 @@ static int next_pidmap(struct pid_namespace *pid_ns, int last)
 
 fastcall void put_pid(struct pid *pid)
 {
+       struct pid_namespace *ns;
+
        if (!pid)
                return;
+
+       /* FIXME - this must be the namespace this pid lives in */
+       ns = &init_pid_ns;
        if ((atomic_read(&pid->count) == 1) ||
             atomic_dec_and_test(&pid->count))
-               kmem_cache_free(pid_cachep, pid);
+               kmem_cache_free(ns->pid_cachep, pid);
 }
 EXPORT_SYMBOL_GPL(put_pid);
 
@@ -208,12 +217,14 @@ struct pid *alloc_pid(void)
        struct pid *pid;
        enum pid_type type;
        int nr = -1;
+       struct pid_namespace *ns;
 
-       pid = kmem_cache_alloc(pid_cachep, GFP_KERNEL);
+       ns = task_active_pid_ns(current);
+       pid = kmem_cache_alloc(ns->pid_cachep, GFP_KERNEL);
        if (!pid)
                goto out;
 
-       nr = alloc_pidmap(current->nsproxy->pid_ns);
+       nr = alloc_pidmap(ns);
        if (nr < 0)
                goto out_free;
 
@@ -230,7 +241,7 @@ out:
        return pid;
 
 out_free:
-       kmem_cache_free(pid_cachep, pid);
+       kmem_cache_free(ns->pid_cachep, pid);
        pid = NULL;
        goto out;
 }
@@ -358,14 +369,64 @@ struct pid *find_ge_pid(int nr)
                pid = find_pid(nr);
                if (pid)
                        break;
-               nr = next_pidmap(current->nsproxy->pid_ns, nr);
+               nr = next_pidmap(task_active_pid_ns(current), nr);
        } while (nr > 0);
 
        return pid;
 }
 EXPORT_SYMBOL_GPL(find_get_pid);
 
-struct pid_namespace *copy_pid_ns(int flags, struct pid_namespace *old_ns)
+struct pid_cache {
+       int nr_ids;
+       char name[16];
+       struct kmem_cache *cachep;
+       struct list_head list;
+};
+
+static LIST_HEAD(pid_caches_lh);
+static DEFINE_MUTEX(pid_caches_mutex);
+
+/*
+ * creates the kmem cache to allocate pids from.
+ * @nr_ids: the number of numerical ids this pid will have to carry
+ */
+
+static struct kmem_cache *create_pid_cachep(int nr_ids)
+{
+       struct pid_cache *pcache;
+       struct kmem_cache *cachep;
+
+       mutex_lock(&pid_caches_mutex);
+       list_for_each_entry (pcache, &pid_caches_lh, list)
+               if (pcache->nr_ids == nr_ids)
+                       goto out;
+
+       pcache = kmalloc(sizeof(struct pid_cache), GFP_KERNEL);
+       if (pcache == NULL)
+               goto err_alloc;
+
+       snprintf(pcache->name, sizeof(pcache->name), "pid_%d", nr_ids);
+       cachep = kmem_cache_create(pcache->name,
+                       /* FIXME add numerical ids here */
+                       sizeof(struct pid), 0, SLAB_HWCACHE_ALIGN, NULL);
+       if (cachep == NULL)
+               goto err_cachep;
+
+       pcache->nr_ids = nr_ids;
+       pcache->cachep = cachep;
+       list_add(&pcache->list, &pid_caches_lh);
+out:
+       mutex_unlock(&pid_caches_mutex);
+       return pcache->cachep;
+
+err_cachep:
+       kfree(pcache);
+err_alloc:
+       mutex_unlock(&pid_caches_mutex);
+       return NULL;
+}
+
+struct pid_namespace *copy_pid_ns(unsigned long flags, struct pid_namespace *old_ns)
 {
        BUG_ON(!old_ns);
        get_pid_ns(old_ns);
@@ -412,5 +473,7 @@ void __init pidmap_init(void)
        set_bit(0, init_pid_ns.pidmap[0].page);
        atomic_dec(&init_pid_ns.pidmap[0].nr_free);
 
-       pid_cachep = KMEM_CACHE(pid, SLAB_PANIC);
+       init_pid_ns.pid_cachep = create_pid_cachep(1);
+       if (init_pid_ns.pid_cachep == NULL)
+               panic("Can't create pid_1 cachep\n");
 }