gcov: enable GCOV_PROFILE_ALL for x86_64
[linux-2.6.git] / kernel / pid.c
index 9c80bc2..31310b5 100644 (file)
  * allocation scenario when all but one out of 1 million PIDs possible are
  * allocated already: the scanning of 32 list entries and at most PAGE_SIZE
  * bytes. The typical fastpath is a single successful setbit. Freeing is O(1).
+ *
+ * Pid namespaces:
+ *    (C) 2007 Pavel Emelyanov <xemul@openvz.org>, OpenVZ, SWsoft Inc.
+ *    (C) 2007 Sukadev Bhattiprolu <sukadev@us.ibm.com>, IBM
+ *     Many thanks to Oleg Nesterov for comments and help
+ *
  */
 
 #include <linux/mm.h>
 #include <linux/module.h>
 #include <linux/slab.h>
 #include <linux/init.h>
+#include <linux/rculist.h>
 #include <linux/bootmem.h>
 #include <linux/hash.h>
 #include <linux/pid_namespace.h>
+#include <linux/init_task.h>
+#include <linux/syscalls.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;
-static struct kmem_cache *pid_cachep;
+struct pid init_struct_pid = INIT_STRUCT_PID;
 
 int pid_max = PID_MAX_DEFAULT;
 
@@ -66,8 +76,25 @@ struct pid_namespace init_pid_ns = {
                [ 0 ... PIDMAP_ENTRIES-1] = { ATOMIC_INIT(BITS_PER_PAGE), NULL }
        },
        .last_pid = 0,
-       .child_reaper = &init_task
+       .level = 0,
+       .child_reaper = &init_task,
 };
+EXPORT_SYMBOL_GPL(init_pid_ns);
+
+int is_container_init(struct task_struct *tsk)
+{
+       int ret = 0;
+       struct pid *pid;
+
+       rcu_read_lock();
+       pid = task_pid(tsk);
+       if (pid != NULL && pid->numbers[pid->level].nr == 1)
+               ret = 1;
+       rcu_read_unlock();
+
+       return ret;
+}
+EXPORT_SYMBOL(is_container_init);
 
 /*
  * Note: disable interrupts while the pidmap_lock is held as an
@@ -85,10 +112,11 @@ struct pid_namespace init_pid_ns = {
 
 static  __cacheline_aligned_in_smp DEFINE_SPINLOCK(pidmap_lock);
 
-static fastcall void free_pidmap(struct pid_namespace *pid_ns, int pid)
+static void free_pidmap(struct upid *upid)
 {
-       struct pidmap *map = pid_ns->pidmap + pid / BITS_PER_PAGE;
-       int offset = pid & BITS_PER_PAGE_MASK;
+       int nr = upid->nr;
+       struct pidmap *map = upid->ns->pidmap + nr / BITS_PER_PAGE;
+       int offset = nr & BITS_PER_PAGE_MASK;
 
        clear_bit(offset, map->page);
        atomic_inc(&map->nr_free);
@@ -154,7 +182,7 @@ static int alloc_pidmap(struct pid_namespace *pid_ns)
        return -1;
 }
 
-static int next_pidmap(struct pid_namespace *pid_ns, int last)
+int next_pidmap(struct pid_namespace *pid_ns, int last)
 {
        int offset;
        struct pidmap *map, *end;
@@ -172,13 +200,19 @@ static int next_pidmap(struct pid_namespace *pid_ns, int last)
        return -1;
 }
 
-fastcall void put_pid(struct pid *pid)
+void put_pid(struct pid *pid)
 {
+       struct pid_namespace *ns;
+
        if (!pid)
                return;
+
+       ns = pid->numbers[pid->level].ns;
        if ((atomic_read(&pid->count) == 1) ||
-            atomic_dec_and_test(&pid->count))
-               kmem_cache_free(pid_cachep, pid);
+            atomic_dec_and_test(&pid->count)) {
+               kmem_cache_free(ns->pid_cachep, pid);
+               put_pid_ns(ns);
+       }
 }
 EXPORT_SYMBOL_GPL(put_pid);
 
@@ -188,78 +222,108 @@ static void delayed_put_pid(struct rcu_head *rhp)
        put_pid(pid);
 }
 
-fastcall void free_pid(struct pid *pid)
+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);
+
        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;
+       int i, nr;
+       struct pid_namespace *tmp;
+       struct upid *upid;
 
-       pid = kmem_cache_alloc(pid_cachep, GFP_KERNEL);
+       pid = kmem_cache_alloc(ns->pid_cachep, GFP_KERNEL);
        if (!pid)
                goto out;
 
-       nr = alloc_pidmap(current->nsproxy->pid_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;
+       }
 
+       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 = ns->level; i >= 0; i--) {
+               upid = &pid->numbers[i];
+               hlist_add_head_rcu(&upid->pid_chain,
+                               &pid_hash[pid_hashfn(upid->nr, upid->ns)]);
+       }
        spin_unlock_irq(&pidmap_lock);
 
 out:
        return pid;
 
 out_free:
-       kmem_cache_free(pid_cachep, pid);
+       while (++i <= ns->level)
+               free_pidmap(pid->numbers + i);
+
+       kmem_cache_free(ns->pid_cachep, pid);
        pid = NULL;
        goto out;
 }
 
-struct pid * fastcall find_pid(int nr)
+struct pid *find_pid_ns(int nr, struct pid_namespace *ns)
 {
        struct hlist_node *elem;
-       struct pid *pid;
+       struct upid *pnr;
+
+       hlist_for_each_entry_rcu(pnr, elem,
+                       &pid_hash[pid_hashfn(nr, ns)], pid_chain)
+               if (pnr->nr == nr && pnr->ns == ns)
+                       return container_of(pnr, struct pid,
+                                       numbers[ns->level]);
 
-       hlist_for_each_entry_rcu(pid, elem,
-                       &pid_hash[pid_hashfn(nr)], pid_chain) {
-               if (pid->nr == nr)
-                       return pid;
-       }
        return NULL;
 }
-EXPORT_SYMBOL_GPL(find_pid);
+EXPORT_SYMBOL_GPL(find_pid_ns);
 
-int fastcall attach_pid(struct task_struct *task, enum pid_type type, int nr)
+struct pid *find_vpid(int nr)
+{
+       return find_pid_ns(nr, current->nsproxy->pid_ns);
+}
+EXPORT_SYMBOL_GPL(find_vpid);
+
+/*
+ * attach_pid() must be called with the tasklist_lock write-held.
+ */
+void attach_pid(struct task_struct *task, enum pid_type type,
+               struct pid *pid)
 {
        struct pid_link *link;
-       struct pid *pid;
 
        link = &task->pids[type];
-       link->pid = pid = find_pid(nr);
+       link->pid = pid;
        hlist_add_head_rcu(&link->node, &pid->tasks[type]);
-
-       return 0;
 }
 
-void fastcall detach_pid(struct task_struct *task, enum pid_type type)
+static void __change_pid(struct task_struct *task, enum pid_type type,
+                       struct pid *new)
 {
        struct pid_link *link;
        struct pid *pid;
@@ -269,7 +333,7 @@ void fastcall detach_pid(struct task_struct *task, enum pid_type type)
        pid = link->pid;
 
        hlist_del_rcu(&link->node);
-       link->pid = NULL;
+       link->pid = new;
 
        for (tmp = PIDTYPE_MAX; --tmp >= 0; )
                if (!hlist_empty(&pid->tasks[tmp]))
@@ -278,16 +342,27 @@ void fastcall detach_pid(struct task_struct *task, enum pid_type type)
        free_pid(pid);
 }
 
+void detach_pid(struct task_struct *task, enum pid_type type)
+{
+       __change_pid(task, type, NULL);
+}
+
+void change_pid(struct task_struct *task, enum pid_type type,
+               struct pid *pid)
+{
+       __change_pid(task, type, pid);
+       attach_pid(task, type, pid);
+}
+
 /* transfer_pid is an optimization of attach_pid(new), detach_pid(old) */
-void fastcall transfer_pid(struct task_struct *old, struct task_struct *new,
+void transfer_pid(struct task_struct *old, struct task_struct *new,
                           enum pid_type type)
 {
        new->pids[type].pid = old->pids[type].pid;
        hlist_replace_rcu(&old->pids[type].node, &new->pids[type].node);
-       old->pids[type].pid = NULL;
 }
 
-struct task_struct * fastcall pid_task(struct pid *pid, enum pid_type type)
+struct task_struct *pid_task(struct pid *pid, enum pid_type type)
 {
        struct task_struct *result = NULL;
        if (pid) {
@@ -298,27 +373,33 @@ struct task_struct * fastcall pid_task(struct pid *pid, enum pid_type type)
        }
        return result;
 }
+EXPORT_SYMBOL(pid_task);
 
 /*
  * Must be called under rcu_read_lock() or with tasklist_lock read-held.
  */
-struct task_struct *find_task_by_pid_type(int type, int nr)
+struct task_struct *find_task_by_pid_ns(pid_t nr, struct pid_namespace *ns)
 {
-       return pid_task(find_pid(nr), type);
+       return pid_task(find_pid_ns(nr, ns), PIDTYPE_PID);
 }
 
-EXPORT_SYMBOL(find_task_by_pid_type);
+struct task_struct *find_task_by_vpid(pid_t vnr)
+{
+       return find_task_by_pid_ns(vnr, current->nsproxy->pid_ns);
+}
 
 struct pid *get_task_pid(struct task_struct *task, enum pid_type type)
 {
        struct pid *pid;
        rcu_read_lock();
+       if (type != PIDTYPE_PID)
+               task = task->group_leader;
        pid = get_pid(task->pids[type].pid);
        rcu_read_unlock();
        return pid;
 }
 
-struct task_struct *fastcall get_pid_task(struct pid *pid, enum pid_type type)
+struct task_struct *get_pid_task(struct pid *pid, enum pid_type type)
 {
        struct task_struct *result;
        rcu_read_lock();
@@ -334,50 +415,80 @@ struct pid *find_get_pid(pid_t nr)
        struct pid *pid;
 
        rcu_read_lock();
-       pid = get_pid(find_pid(nr));
+       pid = get_pid(find_vpid(nr));
        rcu_read_unlock();
 
        return pid;
 }
+EXPORT_SYMBOL_GPL(find_get_pid);
 
-/*
- * Used by proc to find the first pid that is greater then or equal to nr.
- *
- * If there is a pid at nr this function is exactly the same as find_pid.
- */
-struct pid *find_ge_pid(int nr)
+pid_t pid_nr_ns(struct pid *pid, struct pid_namespace *ns)
 {
-       struct pid *pid;
+       struct upid *upid;
+       pid_t nr = 0;
 
-       do {
-               pid = find_pid(nr);
-               if (pid)
-                       break;
-               nr = next_pidmap(current->nsproxy->pid_ns, nr);
-       } while (nr > 0);
+       if (pid && ns->level <= pid->level) {
+               upid = &pid->numbers[ns->level];
+               if (upid->ns == ns)
+                       nr = upid->nr;
+       }
+       return nr;
+}
 
-       return pid;
+pid_t pid_vnr(struct pid *pid)
+{
+       return pid_nr_ns(pid, current->nsproxy->pid_ns);
 }
-EXPORT_SYMBOL_GPL(find_get_pid);
+EXPORT_SYMBOL_GPL(pid_vnr);
 
-int copy_pid_ns(int flags, struct task_struct *tsk)
+pid_t __task_pid_nr_ns(struct task_struct *task, enum pid_type type,
+                       struct pid_namespace *ns)
 {
-       struct pid_namespace *old_ns = tsk->nsproxy->pid_ns;
-       int err = 0;
+       pid_t nr = 0;
 
-       if (!old_ns)
-               return 0;
+       rcu_read_lock();
+       if (!ns)
+               ns = current->nsproxy->pid_ns;
+       if (likely(pid_alive(task))) {
+               if (type != PIDTYPE_PID)
+                       task = task->group_leader;
+               nr = pid_nr_ns(task->pids[type].pid, ns);
+       }
+       rcu_read_unlock();
 
-       get_pid_ns(old_ns);
-       return err;
+       return nr;
 }
+EXPORT_SYMBOL(__task_pid_nr_ns);
 
-void free_pid_ns(struct kref *kref)
+pid_t task_tgid_nr_ns(struct task_struct *tsk, struct pid_namespace *ns)
 {
-       struct pid_namespace *ns;
+       return pid_nr_ns(task_tgid(tsk), ns);
+}
+EXPORT_SYMBOL(task_tgid_nr_ns);
+
+struct pid_namespace *task_active_pid_ns(struct task_struct *tsk)
+{
+       return ns_of_pid(task_pid(tsk));
+}
+EXPORT_SYMBOL_GPL(task_active_pid_ns);
 
-       ns = container_of(kref, struct pid_namespace, kref);
-       kfree(ns);
+/*
+ * Used by proc to find the first pid that is greater than or equal to nr.
+ *
+ * If there is a pid at nr this function is exactly the same as find_pid_ns.
+ */
+struct pid *find_ge_pid(int nr, struct pid_namespace *ns)
+{
+       struct pid *pid;
+
+       do {
+               pid = find_pid_ns(nr, ns);
+               if (pid)
+                       break;
+               nr = next_pidmap(ns, nr);
+       } while (nr > 0);
+
+       return pid;
 }
 
 /*
@@ -412,5 +523,6 @@ 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 = KMEM_CACHE(pid,
+                       SLAB_HWCACHE_ALIGN | SLAB_PANIC);
 }