Re: [PATCH 06/22] audit: Abstract hash key handling

On Thu, Dec 22, 2016 at 4:15 AM, Jan Kara <jack(a)suse.cz&gt; wrote: > Audit tree currently uses inode pointer as a key into the hash table. > Getting that from notification mark will be somewhat more difficult with > coming fsnotify changes and there's no reason we really have to use the > inode pointer. So abstract getting of hash key from the audit chunk and > inode so that we can switch to a different key easily later. > > CC: Paul Moore <paul(a)paul-moore.com&gt; > Signed-off-by: Jan Kara <jack(a)suse.cz&gt; > --- > kernel/audit_tree.c | 39 ++++++++++++++++++++++++++++----------- > 1 file changed, 28 insertions(+), 11 deletions(-) I have no objections with this patch in particular, but in patch 8, are you certain that inode_to_key() and chunk_to_key() will continue to return the same key value?

> diff --git a/kernel/audit_tree.c b/kernel/audit_tree.c > index 156b6a93f4fc..f0859828de09 100644 > --- a/kernel/audit_tree.c > +++ b/kernel/audit_tree.c > @@ -163,33 +163,48 @@ enum {HASH_SIZE = 128}; > static struct list_head chunk_hash_heads[HASH_SIZE]; > static __cacheline_aligned_in_smp DEFINE_SPINLOCK(hash_lock); > > -static inline struct list_head *chunk_hash(const struct inode *inode) > +/* Function to return search key in our hash from inode. */ > +static unsigned long inode_to_key(const struct inode *inode) > { > - unsigned long n = (unsigned long)inode / L1_CACHE_BYTES; > + return (unsigned long)inode; > +} > + > +/* > + * Function to return search key in our hash from chunk. Key 0 is special and > + * should never be present in the hash. > + */ > +static unsigned long chunk_to_key(struct audit_chunk *chunk) > +{ > + return (unsigned long)chunk->mark.inode; > +} > + > +static inline struct list_head *chunk_hash(unsigned long key) > +{ > + unsigned long n = key / L1_CACHE_BYTES; > return chunk_hash_heads + n % HASH_SIZE; > } > > /* hash_lock & entry->lock is held by caller */ > static void insert_hash(struct audit_chunk *chunk) > { > - struct fsnotify_mark *entry = &chunk->mark; > + unsigned long key = chunk_to_key(chunk); > struct list_head *list; > > - if (!entry->inode) > + if (!key) > return; > - list = chunk_hash(entry->inode); > + list = chunk_hash(key); > list_add_rcu(&chunk->hash, list); > } > > /* called under rcu_read_lock */ > struct audit_chunk *audit_tree_lookup(const struct inode *inode) > { > - struct list_head *list = chunk_hash(inode); > + unsigned long key = inode_to_key(inode); > + struct list_head *list = chunk_hash(key); > struct audit_chunk *p; > > list_for_each_entry_rcu(p, list, hash) { > - /* mark.inode may have gone NULL, but who cares? */ > - if (p->mark.inode == inode) { > + if (chunk_to_key(p) == key) { > atomic_long_inc(&p->refs); > return p; > } > @@ -585,7 +600,8 @@ int audit_remove_tree_rule(struct audit_krule *rule) > > static int compare_root(struct vfsmount *mnt, void *arg) > { > - return d_backing_inode(mnt->mnt_root) == arg; > + return inode_to_key(d_backing_inode(mnt->mnt_root)) == > + (unsigned long)arg; > } > > void audit_trim_trees(void) > @@ -620,9 +636,10 @@ void audit_trim_trees(void) > list_for_each_entry(node, &tree->chunks, list) { > struct audit_chunk *chunk = find_chunk(node); > /* this could be NULL if the watch is dying else where... */ > - struct inode *inode = chunk->mark.inode; > node->index |= 1U<<31; > - if (iterate_mounts(compare_root, inode, root_mnt)) > + if (iterate_mounts(compare_root, > + (void *)chunk_to_key(chunk), > + root_mnt)) > node->index &= ~(1U<<31); > } > spin_unlock(&hash_lock); > -- > 2.10.2 > -- paul moore www.paul-moore.com