Revert "xen/p2m: m2p_find_override: use list_for_each_entry_safe"

This reverts commit b960d6c43a63ebd2d8518b328da3816b833ee8cc.

If we have another thread (very likely) touched the list, we
end up hitting a problem "that the next element is wrong because
we should be able to cope with that. The problem is that the
next->next pointer would be set LIST_POISON1. " (Stefano's
comment on the patch).

Reverting for now.

Suggested-by: Dan Carpenter <dan.carpenter@oracle.com>
Acked-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>

1 files changed, 6 insertions, 2 deletions

diff --git a/arch/x86/xen/p2m.c b/arch/x86/xen/p2m.c
index 7ed8cc3434c5..1b267e75158d 100644
--- a/arch/x86/xen/p2m.c
+++ b/arch/x86/xen/p2m.c
@@ -809,17 +809,21 @@ struct page *m2p_find_override(unsigned long mfn)
 {
         unsigned long flags;
         struct list_head *bucket = &m2p_overrides[mfn_hash(mfn)];
-        struct page *p, *t, *ret;
+        struct page *p, *ret;
 
         ret = NULL;
 
-        list_for_each_entry_safe(p, t, bucket, lru) {
+        spin_lock_irqsave(&m2p_override_lock, flags);
+
+        list_for_each_entry(p, bucket, lru) {
                 if (page_private(p) == mfn) {
                         ret = p;
                         break;
                 }
         }
 
+        spin_unlock_irqrestore(&m2p_override_lock, flags);
+
         return ret;
 }