Re: [PATCH 11/14] audit: Drop all unused chunk nodes during deletion

[Paul Moore <paul@paul-moore.com>]

On Wed, Oct 17, 2018 at 6:15 AM Jan Kara <jack@suse.cz> wrote:
> When deleting chunk from a tree, drop all unused nodes in a chunk
> instead of just the one used by the tree. This gets rid of possibly
> lingering unused nodes (created due to fallback path in untag_chunk())
> and also removes some special cases and will allow us to simplify
> locking in untag_chunk().
>
> Signed-off-by: Jan Kara <jack@suse.cz>
> ---
>  kernel/audit_tree.c | 27 ++++++++++++++++++---------
>  1 file changed, 18 insertions(+), 9 deletions(-)

Hmmm, it looks like this is the patch which makes the list
replace->splice change okay, yes?  If so, should this change be
squashed into the replace_chunk() patch?

> diff --git a/kernel/audit_tree.c b/kernel/audit_tree.c
> index ca2b6baff7aa..145e8c92dd31 100644
> --- a/kernel/audit_tree.c
> +++ b/kernel/audit_tree.c
> @@ -277,8 +277,7 @@ 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)
> +static void replace_chunk(struct audit_chunk *new, struct audit_chunk *old)
>  {
>         struct audit_tree *owner;
>         int i, j;
> @@ -288,7 +287,7 @@ static void replace_chunk(struct audit_chunk *new, struct audit_chunk *old,
>         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) {
> +               if (!old->owners[j].owner) {
>                         i--;
>                         continue;
>                 }
> @@ -322,20 +321,28 @@ static void remove_chunk_node(struct audit_chunk *chunk, struct node *p)
>         put_tree(owner);
>  }
>
> +static int chunk_count_trees(struct audit_chunk *chunk)
> +{
> +       int i;
> +       int ret = 0;
> +
> +       for (i = 0; i < chunk->count; i++)
> +               if (chunk->owners[i].owner)
> +                       ret++;
> +       return ret;
> +}
> +
>  static void untag_chunk(struct node *p)
>  {
>         struct audit_chunk *chunk = find_chunk(p);
>         struct fsnotify_mark *entry = chunk->mark;
>         struct audit_chunk *new = NULL;
> -       int size = chunk->count - 1;
> +       int size;
>
>         remove_chunk_node(chunk, p);
>         fsnotify_get_mark(entry);
>         spin_unlock(&hash_lock);
>
> -       if (size)
> -               new = alloc_chunk(size);
> -
>         mutex_lock(&entry->group->mark_mutex);
>         /*
>          * mark_mutex protects mark from getting detached and thus also from
> @@ -348,6 +355,7 @@ static void untag_chunk(struct node *p)
>                 goto out;
>         }
>
> +       size = chunk_count_trees(chunk);
>         if (!size) {
>                 chunk->dead = 1;
>                 spin_lock(&hash_lock);
> @@ -360,6 +368,7 @@ static void untag_chunk(struct node *p)
>                 goto out;
>         }
>
> +       new = alloc_chunk(size);
>         if (!new)
>                 goto out_mutex;
>
> @@ -375,7 +384,7 @@ static void untag_chunk(struct node *p)
>          * This has to go last when updating chunk as once replace_chunk() is
>          * called, new RCU readers can see the new chunk.
>          */
> -       replace_chunk(new, chunk, p);
> +       replace_chunk(new, chunk);
>         spin_unlock(&hash_lock);
>         fsnotify_detach_mark(entry);
>         mutex_unlock(&entry->group->mark_mutex);
> @@ -520,7 +529,7 @@ static int tag_chunk(struct inode *inode, struct audit_tree *tree)
>          * This has to go last when updating chunk as once replace_chunk() is
>          * called, new RCU readers can see the new chunk.
>          */
> -       replace_chunk(chunk, old, NULL);
> +       replace_chunk(chunk, old);
>         spin_unlock(&hash_lock);
>         fsnotify_detach_mark(old_entry);
>         mutex_unlock(&audit_tree_group->mark_mutex);
> --
> 2.16.4
>


-- 
paul moore
www.paul-moore.com