[PATCH] free_uid() locking improvement
Reduce lock hold times in free_uid().
Cc: Ingo Molnar <mingo@elte.hu>
Cc: "Paul E. McKenney" <paulmck@us.ibm.com>
Cc: David Howells <dhowells@redhat.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/kernel/user.c b/kernel/user.c
index d9deae4..2116642 100644
--- a/kernel/user.c
+++ b/kernel/user.c
@@ -105,15 +105,19 @@
{
unsigned long flags;
+ if (!up)
+ return;
+
local_irq_save(flags);
- if (up && atomic_dec_and_lock(&up->__count, &uidhash_lock)) {
+ if (atomic_dec_and_lock(&up->__count, &uidhash_lock)) {
uid_hash_remove(up);
+ spin_unlock_irqrestore(&uidhash_lock, flags);
key_put(up->uid_keyring);
key_put(up->session_keyring);
kmem_cache_free(uid_cachep, up);
- spin_unlock(&uidhash_lock);
+ } else {
+ local_irq_restore(flags);
}
- local_irq_restore(flags);
}
struct user_struct * alloc_uid(uid_t uid)