[PATCH 13/16] Switch to operating with pid_numbers instead of pids

Pavel Emelianov
2007-07-06T08:13:23Z

Make alloc_pid() initialize pid_numbers and hash them
into the hashtable, not the struct pid itself.

Signed-off-by: Pavel Emelianov <xemul@openvz.org>

---

pid.c | 47 +++++++++++++++++++++++++++++++++--------------
1 files changed, 33 insertions(+), 14 deletions(-)

--- ./kernel/pid.c.ve12 2007-07-05 11:06:41.000000000 +0400
+++ ./kernel/pid.c 2007-07-05 11:08:23.000000000 +0400
@@ -28,8 +28,10 @@
#include <linux/hash.h>
#include <linux/pid_namespace.h>
#include <linux/init_task.h>
+#include <linux/proc_fs.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;
@@ -194,7 +198,7 @@ fastcall void put_pid(struct pid *pid)
if (!pid)
return;

- ns = pid->numbers[0].ns;
+ ns = pid->numbers[pid->level].ns;
if ((atomic_read(&pid->count) == 1) ||
atomic_dec_and_test(&pid->count))
kmem_cache_free(ns->pid_cachep, pid);
@@ -210,13 +214,17 @@ static void delayed_put_pid(struct rcu_h
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);
+ 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].ns, pid->numbers[i].nr);
+
call_rcu(&pid->rcu, delayed_put_pid);
}

@@ -224,30 +232,43 @@ struct pid *alloc_pid(struct pid_namespa
{
struct pid *pid;
enum pid_type type;
- int nr = -1;
+ struct pid_namespace *ns;
+ int i, nr;

- pid = kmem_cache_alloc(init_pid_ns.pid_cachep, GFP_KERNEL);
+ pid = kmem_cache_alloc(pid_ns->pid_cachep, GFP_KERNEL);
if (!pid)
goto out;

- nr = alloc_pidmap(current->nsproxy->pid_ns);
- if (nr < 0)
- goto out_free;
+ ns = pid_ns;
+ for (i = pid_ns->level; i >= 0; i--) {
+ nr = alloc_pidmap(ns);
+ if (nr < 0)
+ goto out_free;

+ pid->numbers[i].nr = nr;
+ pid->numbers[i].ns = ns;
+ ns = ns->parent;
+ }
+
+ pid->level = pid_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 = pid->level; i >= 0; i--)
+ hlist_add_head_rcu(&pid->numbers[i].pid_chain,
+ &pid_hash[pid_hashfn(pid->numbers[i].nr,
+ pid->numbers[i].ns)]);
spin_unlock_irq(&pidmap_lock);
-
out:
return pid;

out_free:
- kmem_cache_free(init_pid_ns.pid_cachep, pid);
+ for (i++; i <= pid->level; i++)
+ free_pidmap(pid->numbers[i].ns, pid->numbers[i].nr);
+
+ kmem_cache_free(pid_ns->pid_cachep, pid);
pid = NULL;
goto out;
}
@@ -258,7 +279,7 @@ struct pid * fastcall find_pid_ns(int nr
struct pid_number *pnr;

hlist_for_each_entry_rcu(pnr, elem,
- &pid_hash[pid_hashfn(nr)], pid_chain)
+ &pid_hash[pid_hashfn(nr, ns)], pid_chain)
if (pnr->nr == nr && pnr->ns == ns)
return container_of(pnr, struct pid,
numbers[ns->level]);