From 8ef047aaaeb811247a5639c92e2f2ae1221a28dd Mon Sep 17 00:00:00 2001 From: Pavel Emelyanov Date: Thu, 18 Oct 2007 23:40:05 -0700 Subject: [PATCH] pid namespaces: make alloc_pid(), free_pid() and put_pid() work with struct upid 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 Cc: Oleg Nesterov Cc: Sukadev Bhattiprolu Cc: Paul Menage Cc: "Eric W. Biederman" Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/pid.h | 2 +- kernel/fork.c | 2 +- kernel/pid.c | 49 +++++++++++++++++++++++++++++++-------------- 3 files changed, 36 insertions(+), 17 deletions(-) diff --git a/include/linux/pid.h b/include/linux/pid.h index e5865a9c58..67470ade32 100644 --- a/include/linux/pid.h +++ b/include/linux/pid.h @@ -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) diff --git a/kernel/fork.c b/kernel/fork.c index d2f4a420a5..984d259e17 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -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; } diff --git a/kernel/pid.c b/kernel/pid.c index c7346fb801..8132a6ddfa 100644 --- a/kernel/pid.c +++ b/kernel/pid.c @@ -29,7 +29,8 @@ #include #include -#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; } -- 2.39.5