Commit 7be6d991 authored Dec 15, 2009 by André Goddard Rosa Committed by Linus Torvalds Dec 16, 2009

pid: tighten pidmap spinlock critical section by removing kfree()

Avoid calling kfree() under pidmap spinlock, calling it afterwards.

Normally kfree() is fast, but sometimes it can be slow, so avoid
calling it under the spinlock if we can do it.

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>

parent 698ba7b5

kernel/pid.c

+4 −3

Original line number	Original line	Diff line number	Diff line
	@@ -141,11 +141,12 @@ static int alloc_pidmap(struct pid_namespace *pid_ns)
	* installing it:		* installing it:
	*/		*/
	spin_lock_irq(&pidmap_lock);		spin_lock_irq(&pidmap_lock);
	if (map->page)		if (!map->page) {
	kfree(page);
	else
	map->page = page;		map->page = page;
			page = NULL;
			}
	spin_unlock_irq(&pidmap_lock);		spin_unlock_irq(&pidmap_lock);
			kfree(page);
	if (unlikely(!map->page))		if (unlikely(!map->page))
	break;		break;
	}		}