[PATCH 06/14] audit: Factor out chunk replacement code

Jan Kara
2018-10-17T10:14:57Z

Chunk replacement code is very similar for the cases where we grow or
shrink chunk. Factor the code out into a common helper function.

Signed-off-by: Jan Kara <jack@suse.cz>
---
kernel/audit_tree.c | 86 +++++++++++++++++++++++++----------------------------
1 file changed, 40 insertions(+), 46 deletions(-)

diff --git a/kernel/audit_tree.c b/kernel/audit_tree.c
index 307749d6773c..d8f6cfa0005b 100644
--- a/kernel/audit_tree.c
+++ b/kernel/audit_tree.c
@@ -235,6 +235,38 @@ static struct audit_chunk *find_chunk(struct node *p)
return container_of(p, struct audit_chunk, owners[0]);
}

+static void replace_chunk(struct audit_chunk *new, struct audit_chunk *old,
+ struct node *skip)
+{
+ struct audit_tree *owner;
+ int i, j;
+
+ new->key = old->key;
+ list_splice_init(&old->trees, &new->trees);
+ list_for_each_entry(owner, &new->trees, same_root)
+ owner->root = new;
+ for (i = j = 0; j < old->count; i++, j++) {
+ if (&old->owners[j] == skip) {
+ i--;
+ continue;
+ }
+ owner = old->owners[j].owner;
+ new->owners[i].owner = owner;
+ new->owners[i].index = old->owners[j].index - j + i;
+ if (!owner) /* result of earlier fallback */
+ continue;
+ get_tree(owner);
+ list_replace_init(&old->owners[j].list, &new->owners[i].list);
+ }
+ /*
+ * Make sure chunk is fully initialized before making it visible in the
+ * hash. Pairs with a data dependency barrier in READ_ONCE() in
+ * audit_tree_lookup().
+ */
+ smp_wmb();
+ list_replace_rcu(&old->hash, &new->hash);
+}
+
static void untag_chunk(struct node *p)
{
struct audit_chunk *chunk = find_chunk(p);
@@ -242,7 +274,6 @@ static void untag_chunk(struct node *p)
struct audit_chunk *new = NULL;
struct audit_tree *owner;
int size = chunk->count - 1;
- int i, j;

fsnotify_get_mark(entry);

@@ -291,38 +322,16 @@ static void untag_chunk(struct node *p)

chunk->dead = 1;
spin_lock(&hash_lock);
- new->key = chunk->key;
- list_replace_init(&chunk->trees, &new->trees);
if (owner->root == chunk) {
list_del_init(&owner->same_root);
owner->root = NULL;
}
-
- for (i = j = 0; j <= size; i++, j++) {
- struct audit_tree *s;
- if (&chunk->owners[j] == p) {
- list_del_init(&p->list);
- i--;
- continue;
- }
- s = chunk->owners[j].owner;
- new->owners[i].owner = s;
- new->owners[i].index = chunk->owners[j].index - j + i;
- if (!s) /* result of earlier fallback */
- continue;
- get_tree(s);
- list_replace_init(&chunk->owners[j].list, &new->owners[i].list);
- }
-
- list_for_each_entry(owner, &new->trees, same_root)
- owner->root = new;
+ list_del_init(&p->list);
/*
- * Make sure chunk is fully initialized before making it visible in the
- * hash. Pairs with a data dependency barrier in READ_ONCE() in
- * audit_tree_lookup().
+ * This has to go last when updating chunk as once replace_chunk() is
+ * called, new RCU readers can see the new chunk.
*/
- smp_wmb();
- list_replace_rcu(&chunk->hash, &new->hash);
+ replace_chunk(new, chunk, p);
spin_unlock(&hash_lock);
fsnotify_detach_mark(entry);
mutex_unlock(&entry->group->mark_mutex);
@@ -399,7 +408,6 @@ static int create_chunk(struct inode *inode, struct audit_tree *tree)
static int tag_chunk(struct inode *inode, struct audit_tree *tree)
{
struct fsnotify_mark *old_entry, *chunk_entry;
- struct audit_tree *owner;
struct audit_chunk *chunk, *old;
struct node *p;
int n;
@@ -464,35 +472,21 @@ static int tag_chunk(struct inode *inode, struct audit_tree *tree)
fsnotify_put_mark(old_entry);
return 0;
}
- chunk->key = old->key;
- list_replace_init(&old->trees, &chunk->trees);
- for (n = 0, p = chunk->owners; n < old->count; n++, p++) {
- struct audit_tree *s = old->owners[n].owner;
- p->owner = s;
- p->index = old->owners[n].index;
- if (!s) /* result of fallback in untag */
- continue;
- get_tree(s);
- list_replace_init(&old->owners[n].list, &p->list);
- }
+ p = &chunk->owners[chunk->count - 1];
p->index = (chunk->count - 1) | (1U<<31);
p->owner = tree;
get_tree(tree);
list_add(&p->list, &tree->chunks);
- list_for_each_entry(owner, &chunk->trees, same_root)
- owner->root = chunk;
old->dead = 1;
if (!tree->root) {
tree->root = chunk;
list_add(&tree->same_root, &chunk->trees);
}
/*
- * Make sure chunk is fully initialized before making it visible in the
- * hash. Pairs with a data dependency barrier in READ_ONCE() in
- * audit_tree_lookup().
+ * This has to go last when updating chunk as once replace_chunk() is
+ * called, new RCU readers can see the new chunk.
*/
- smp_wmb();
- list_replace_rcu(&old->hash, &chunk->hash);
+ replace_chunk(chunk, old, NULL);
spin_unlock(&hash_lock);
fsnotify_detach_mark(old_entry);
mutex_unlock(&audit_tree_group->mark_mutex);
--
2.16.4