pid namespaces: helpers to find the task by its numerical ids
When searching the task by numerical id on may need to find it using global
pid (as it is done now in kernel) or by its virtual id, e.g. when sending a
signal to a task from one namespace the sender will specify the task's virtual
id and we should find the task by this value.
[akpm@linux-foundation.org: fix gfs2 linkage]
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>
diff --git a/kernel/pid.c b/kernel/pid.c
index 6eb1484..a2b4cbb 100644
--- a/kernel/pid.c
+++ b/kernel/pid.c
@@ -71,6 +71,7 @@
.level = 0,
.child_reaper = &init_task,
};
+EXPORT_SYMBOL_GPL(init_pid_ns);
int is_global_init(struct task_struct *tsk)
{
@@ -210,7 +211,8 @@
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);
for (i = 0; i <= pid->level; i++)
@@ -225,6 +227,7 @@
enum pid_type type;
int i, nr;
struct pid_namespace *tmp;
+ struct upid *upid;
pid = kmem_cache_alloc(ns->pid_cachep, GFP_KERNEL);
if (!pid)
@@ -251,7 +254,11 @@
INIT_HLIST_HEAD(&pid->tasks[type]);
spin_lock_irq(&pidmap_lock);
- hlist_add_head_rcu(&pid->pid_chain, &pid_hash[pid_hashfn(pid->nr, ns)]);
+ 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:
@@ -266,19 +273,20 @@
goto out;
}
-struct pid * fastcall find_pid(int nr)
+struct pid * fastcall find_pid_ns(int nr, struct pid_namespace *ns)
{
struct hlist_node *elem;
- struct pid *pid;
+ struct upid *pnr;
- hlist_for_each_entry_rcu(pid, elem,
- &pid_hash[pid_hashfn(nr, &init_pid_ns)], pid_chain) {
- if (pid->nr == nr)
- return pid;
- }
+ 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]);
+
return NULL;
}
-EXPORT_SYMBOL_GPL(find_pid);
+EXPORT_SYMBOL_GPL(find_pid_ns);
/*
* attach_pid() must be called with the tasklist_lock write-held.
@@ -338,12 +346,13 @@
/*
* 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_type_ns(int type, int nr,
+ struct pid_namespace *ns)
{
- return pid_task(find_pid(nr), type);
+ return pid_task(find_pid_ns(nr, ns), type);
}
-EXPORT_SYMBOL(find_task_by_pid_type);
+EXPORT_SYMBOL(find_task_by_pid_type_ns);
struct pid *get_task_pid(struct task_struct *task, enum pid_type type)
{
@@ -370,7 +379,7 @@
struct pid *pid;
rcu_read_lock();
- pid = get_pid(find_pid(nr));
+ pid = get_pid(find_vpid(nr));
rcu_read_unlock();
return pid;
@@ -394,15 +403,15 @@
*
* If there is a pid at nr this function is exactly the same as find_pid.
*/
-struct pid *find_ge_pid(int nr)
+struct pid *find_ge_pid(int nr, struct pid_namespace *ns)
{
struct pid *pid;
do {
- pid = find_pid(nr);
+ pid = find_pid_ns(nr, ns);
if (pid)
break;
- nr = next_pidmap(task_active_pid_ns(current), nr);
+ nr = next_pidmap(ns, nr);
} while (nr > 0);
return pid;