From: Jan Kara <jack@suse.cz>
To: linux-audit@redhat.com
Cc: Paul Moore <paul@paul-moore.com>, <linux-fsdevel@vger.kernel.org>,
Al Viro <viro@ZenIV.linux.org.uk>,
Richard Guy Briggs <rgb@redhat.com>,
Amir Goldstein <amir73il@gmail.com>, Jan Kara <jack@suse.cz>
Subject: [PATCH 06/10] audit: Factor out chunk replacement code
Date: Tue, 10 Jul 2018 12:02:12 +0200 [thread overview]
Message-ID: <20180710100217.12866-7-jack@suse.cz> (raw)
In-Reply-To: <20180710100217.12866-1-jack@suse.cz>
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 6a01738d1ac2..f419fdfc25b4 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_replace_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
next prev parent reply other threads:[~2018-07-10 10:02 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-07-10 10:02 [PATCH 0/10 v2] audit: Fix various races when tagging and untagging mounts Jan Kara
2018-07-10 10:02 ` [PATCH 01/10] audit_tree: Remove mark->lock locking Jan Kara
2018-07-27 4:47 ` Paul Moore
2018-09-04 9:53 ` Jan Kara
2018-07-10 10:02 ` [PATCH 02/10] audit: Fix possible spurious -ENOSPC error Jan Kara
2018-07-27 4:47 ` Paul Moore
2018-09-04 10:00 ` Jan Kara
2018-07-10 10:02 ` [PATCH 03/10] audit: Fix possible tagging failures Jan Kara
2018-07-10 10:02 ` [PATCH 04/10] audit: Embed key into chunk Jan Kara
2018-07-27 4:47 ` Paul Moore
2018-07-10 10:02 ` [PATCH 05/10] audit: Make hash table insertion safe against concurrent lookups Jan Kara
2018-07-10 10:02 ` Jan Kara [this message]
2018-07-11 7:58 ` [PATCH 06/10] audit: Factor out chunk replacement code Amir Goldstein
2018-07-11 8:26 ` Jan Kara
2018-07-11 9:01 ` Amir Goldstein
2018-07-11 9:23 ` Jan Kara
2018-07-27 4:47 ` Paul Moore
2018-07-10 10:02 ` [PATCH 07/10] audit: Remove pointless check in insert_hash() Jan Kara
2018-07-27 4:47 ` Paul Moore
2018-07-10 10:02 ` [PATCH 08/10] audit: Provide helper for dropping mark's chunk reference Jan Kara
2018-07-10 10:02 ` [PATCH 09/10] audit: Allocate fsnotify mark independently of chunk Jan Kara
2018-07-11 8:57 ` Amir Goldstein
2018-07-11 10:48 ` Amir Goldstein
2018-07-16 15:13 ` Jan Kara
2018-07-27 4:47 ` Paul Moore
2018-09-04 14:03 ` Jan Kara
2018-09-04 14:07 ` Jan Kara
2018-07-10 10:02 ` [PATCH 10/10] audit: Replace chunk attached to mark instead of replacing mark Jan Kara
2018-07-11 14:17 ` Amir Goldstein
2018-07-27 4:47 ` Paul Moore
2018-09-04 14:11 ` Jan Kara
2018-07-10 10:02 ` [PATCH 11/10 TESTSUITE] audit_testsuite: Add stress test for tree watches Jan Kara
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