From 31be5bf15f3dafffce110eb1afadccbf2e3067b4 Mon Sep 17 00:00:00 2001 From: Trond Myklebust Date: Sun, 24 Jun 2007 15:55:26 -0400 Subject: SUNRPC: Convert the credcache lookup code to use RCU Signed-off-by: Trond Myklebust --- net/sunrpc/auth.c | 91 ++++++++++++++++++++++++++++++++++--------------------- 1 file changed, 57 insertions(+), 34 deletions(-) (limited to 'net/sunrpc/auth.c') diff --git a/net/sunrpc/auth.c b/net/sunrpc/auth.c index 00f9649b090..ad7bde2c437 100644 --- a/net/sunrpc/auth.c +++ b/net/sunrpc/auth.c @@ -112,6 +112,14 @@ rpcauth_release(struct rpc_auth *auth) static DEFINE_SPINLOCK(rpc_credcache_lock); +static void +rpcauth_unhash_cred_locked(struct rpc_cred *cred) +{ + hlist_del_rcu(&cred->cr_hash); + smp_mb__before_clear_bit(); + clear_bit(RPCAUTH_CRED_HASHED, &cred->cr_flags); +} + /* * Initialize RPC credential cache */ @@ -166,8 +174,7 @@ rpcauth_clear_credcache(struct rpc_cred_cache *cache) cred = hlist_entry(head->first, struct rpc_cred, cr_hash); get_rpccred(cred); list_move_tail(&cred->cr_lru, &free); - smp_wmb(); - hlist_del_init(&cred->cr_hash); + rpcauth_unhash_cred_locked(cred); } } spin_unlock(&rpc_credcache_lock); @@ -207,8 +214,7 @@ rpcauth_prune_expired(struct list_head *free) continue; get_rpccred(cred); list_add_tail(&cred->cr_lru, free); - smp_wmb(); - hlist_del_init(&cred->cr_hash); + rpcauth_unhash_cred_locked(cred); } } @@ -218,10 +224,12 @@ rpcauth_prune_expired(struct list_head *free) static void rpcauth_gc_credcache(struct rpc_cred_cache *cache, struct list_head *free) { - if (time_before(jiffies, cache->nextgc)) + if (list_empty(&cred_unused) || time_before(jiffies, cache->nextgc)) return; + spin_lock(&rpc_credcache_lock); cache->nextgc = jiffies + cache->expire; rpcauth_prune_expired(free); + spin_unlock(&rpc_credcache_lock); } /* @@ -234,42 +242,57 @@ rpcauth_lookup_credcache(struct rpc_auth *auth, struct auth_cred * acred, LIST_HEAD(free); struct rpc_cred_cache *cache = auth->au_credcache; struct hlist_node *pos; - struct rpc_cred *new = NULL, - *cred = NULL, - *entry; + struct rpc_cred *cred = NULL, + *entry, *new; int nr = 0; if (!(flags & RPCAUTH_LOOKUP_ROOTCREDS)) nr = acred->uid & RPC_CREDCACHE_MASK; -retry: - spin_lock(&rpc_credcache_lock); - hlist_for_each_entry(entry, pos, &cache->hashtable[nr], cr_hash) { + + rcu_read_lock(); + hlist_for_each_entry_rcu(entry, pos, &cache->hashtable[nr], cr_hash) { if (!entry->cr_ops->crmatch(acred, entry, flags)) continue; + spin_lock(&rpc_credcache_lock); + if (test_bit(RPCAUTH_CRED_HASHED, &entry->cr_flags) == 0) { + spin_unlock(&rpc_credcache_lock); + continue; + } cred = get_rpccred(entry); - hlist_del(&entry->cr_hash); + spin_unlock(&rpc_credcache_lock); break; } - if (new) { - if (cred) - list_add_tail(&new->cr_lru, &free); - else - cred = new; - } - if (cred) { - hlist_add_head(&cred->cr_hash, &cache->hashtable[nr]); + rcu_read_unlock(); + + if (cred != NULL) { + rpcauth_gc_credcache(cache, &free); + goto found; } - rpcauth_gc_credcache(cache, &free); - spin_unlock(&rpc_credcache_lock); - rpcauth_destroy_credlist(&free); + new = auth->au_ops->crcreate(auth, acred, flags); + if (IS_ERR(new)) { + cred = new; + goto out; + } - if (!cred) { - new = auth->au_ops->crcreate(auth, acred, flags); - if (!IS_ERR(new)) - goto retry; + spin_lock(&rpc_credcache_lock); + hlist_for_each_entry(entry, pos, &cache->hashtable[nr], cr_hash) { + if (!entry->cr_ops->crmatch(acred, entry, flags)) + continue; + cred = get_rpccred(entry); + break; + } + if (cred == NULL) { cred = new; - } else if (test_bit(RPCAUTH_CRED_NEW, &cred->cr_flags) + set_bit(RPCAUTH_CRED_HASHED, &cred->cr_flags); + hlist_add_head_rcu(&cred->cr_hash, &cache->hashtable[nr]); + } else + list_add_tail(&new->cr_lru, &free); + rpcauth_prune_expired(&free); + cache->nextgc = jiffies + cache->expire; + spin_unlock(&rpc_credcache_lock); +found: + if (test_bit(RPCAUTH_CRED_NEW, &cred->cr_flags) && cred->cr_ops->cr_init != NULL && !(flags & RPCAUTH_LOOKUP_NEW)) { int res = cred->cr_ops->cr_init(auth, cred); @@ -278,8 +301,9 @@ retry: cred = ERR_PTR(res); } } - - return (struct rpc_cred *) cred; + rpcauth_destroy_credlist(&free); +out: + return cred; } struct rpc_cred * @@ -357,21 +381,20 @@ void put_rpccred(struct rpc_cred *cred) { /* Fast path for unhashed credentials */ - if (!hlist_unhashed(&cred->cr_hash)) + if (test_bit(RPCAUTH_CRED_HASHED, &cred->cr_flags) != 0) goto need_lock; if (!atomic_dec_and_test(&cred->cr_count)) return; goto out_destroy; - need_lock: if (!atomic_dec_and_lock(&cred->cr_count, &rpc_credcache_lock)) return; if (!list_empty(&cred->cr_lru)) list_del_init(&cred->cr_lru); if (test_bit(RPCAUTH_CRED_UPTODATE, &cred->cr_flags) == 0) - hlist_del(&cred->cr_hash); - else if (!hlist_unhashed(&cred->cr_hash)) { + rpcauth_unhash_cred_locked(cred); + else if (test_bit(RPCAUTH_CRED_HASHED, &cred->cr_flags) != 0) { cred->cr_expire = jiffies; list_add_tail(&cred->cr_lru, &cred_unused); spin_unlock(&rpc_credcache_lock); -- cgit