xen/p2m: m2p_find_override: use list_for_each_entry_safe

Use list_for_each_entry_safe and remove the spin_lock acquisition in
m2p_find_override.
Signed-off-by: NStefano Stabellini <stefano.stabellini@eu.citrix.com>
Signed-off-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>

arch/x86/xen/p2m.c

@@ -809,21 +809,17 @@ struct page *m2p_find_override(unsigned long mfn)
 {
 	unsigned long flags;
 	struct list_head *bucket = &m2p_overrides[mfn_hash(mfn)];
-	struct page *p, *ret;
+	struct page *p, *t, *ret;
 
 	ret = NULL;
 
-	spin_lock_irqsave(&m2p_override_lock, flags);
-
-	list_for_each_entry(p, bucket, lru) {
+	list_for_each_entry_safe(p, t, bucket, lru) {
 		if (page_private(p) == mfn) {
 			ret = p;
 			break;
 		}
 	}
 
-	spin_unlock_irqrestore(&m2p_override_lock, flags);
-
 	return ret;
 }