pid: reduce code size by using a pointer to iterate over array
André Goddard Rosa [Wed, 16 Dec 2009 00:47:40 +0000 (16:47 -0800)]
It decreases code size by 16 bytes on my gcc 4.4.1 on Core 2:
  text    data     bss     dec     hex filename
  4314    2216       8    6538    198a kernel/pid.o-BEFORE
  4298    2216       8    6522    197a kernel/pid.o-AFTER

Signed-off-by: André Goddard Rosa <andre.goddard@gmail.com>
Cc: Pekka Enberg <penberg@cs.helsinki.fi>
Cc: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

kernel/pid.c

index 55fd590..2e17c9c 100644 (file)
@@ -269,12 +269,11 @@ struct pid *alloc_pid(struct pid_namespace *ns)
        for (type = 0; type < PIDTYPE_MAX; ++type)
                INIT_HLIST_HEAD(&pid->tasks[type]);
 
+       upid = pid->numbers + ns->level;
        spin_lock_irq(&pidmap_lock);
-       for (i = ns->level; i >= 0; i--) {
-               upid = &pid->numbers[i];
+       for ( ; upid >= pid->numbers; --upid)
                hlist_add_head_rcu(&upid->pid_chain,
                                &pid_hash[pid_hashfn(upid->nr, upid->ns)]);
-       }
        spin_unlock_irq(&pidmap_lock);
 
 out: