security: use READ_ONCE instead of deprecated ACCESS_ONCE

With the new standardized functions, we can replace all ACCESS_ONCE()
calls across relevant security/keyrings/.

ACCESS_ONCE() does not work reliably on non-scalar types. For example
gcc 4.6 and 4.7 might remove the volatile tag for such accesses during
the SRA (scalar replacement of aggregates) step:

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=58145

Update the new calls regardless of if it is a scalar type, this is
cleaner than having three alternatives.

Signed-off-by: Davidlohr Bueso <dbueso@suse.de>
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: James Morris <james.l.morris@oracle.com>

diff --git a/security/keys/keyring.c b/security/keys/keyring.c
index 4d1678e4586f6ae29610bfb818c33000413947bf..de81793f9920787101dec77eca28ddfbe91ebbc7 100644 (file)
--- a/security/keys/keyring.c
+++ b/security/keys/keyring.c
@@ -706,7 +706,7 @@ descend_to_keyring:
         * Non-keyrings avoid the leftmost branch of the root entirely (root
         * slots 1-15).
         */
-       ptr = ACCESS_ONCE(keyring->keys.root);
+       ptr = READ_ONCE(keyring->keys.root);
        if (!ptr)
                goto not_this_keyring;
 
@@ -720,7 +720,7 @@ descend_to_keyring:
                if ((shortcut->index_key[0] & ASSOC_ARRAY_FAN_MASK) != 0)
                        goto not_this_keyring;
 
-               ptr = ACCESS_ONCE(shortcut->next_node);
+               ptr = READ_ONCE(shortcut->next_node);
                node = assoc_array_ptr_to_node(ptr);
                goto begin_node;
        }
@@ -740,7 +740,7 @@ descend_to_node:
        if (assoc_array_ptr_is_shortcut(ptr)) {
                shortcut = assoc_array_ptr_to_shortcut(ptr);
                smp_read_barrier_depends();
-               ptr = ACCESS_ONCE(shortcut->next_node);
+               ptr = READ_ONCE(shortcut->next_node);
                BUG_ON(!assoc_array_ptr_is_node(ptr));
        }
        node = assoc_array_ptr_to_node(ptr);
@@ -752,7 +752,7 @@ begin_node:
 ascend_to_node:
        /* Go through the slots in a node */
        for (; slot < ASSOC_ARRAY_FAN_OUT; slot++) {
-               ptr = ACCESS_ONCE(node->slots[slot]);
+               ptr = READ_ONCE(node->slots[slot]);
 
                if (assoc_array_ptr_is_meta(ptr) && node->back_pointer)
                        goto descend_to_node;
@@ -790,13 +790,13 @@ ascend_to_node:
        /* We've dealt with all the slots in the current node, so now we need
         * to ascend to the parent and continue processing there.
         */
-       ptr = ACCESS_ONCE(node->back_pointer);
+       ptr = READ_ONCE(node->back_pointer);
        slot = node->parent_slot;
 
        if (ptr && assoc_array_ptr_is_shortcut(ptr)) {
                shortcut = assoc_array_ptr_to_shortcut(ptr);
                smp_read_barrier_depends();
-               ptr = ACCESS_ONCE(shortcut->back_pointer);
+               ptr = READ_ONCE(shortcut->back_pointer);
                slot = shortcut->parent_slot;
        }
        if (!ptr)