@@ -291,25 +291,30 @@ rpcauth_release(struct rpc_auth *auth)
static DEFINE_SPINLOCK(rpc_credcache_lock);
-static void
+/*
+ * On success, the caller is responsible for freeing the reference
+ * held by the hashtable
+ */
+static bool
rpcauth_unhash_cred_locked(struct rpc_cred *cred)
{
+ if (!test_and_clear_bit(RPCAUTH_CRED_HASHED, &cred->cr_flags))
+ return false;
hlist_del_rcu(&cred->cr_hash);
- smp_mb__before_atomic();
- clear_bit(RPCAUTH_CRED_HASHED, &cred->cr_flags);
+ return true;
}
-static int
+static bool
rpcauth_unhash_cred(struct rpc_cred *cred)
{
spinlock_t *cache_lock;
- int ret;
+ bool ret;
+ if (!test_bit(RPCAUTH_CRED_HASHED, &cred->cr_flags))
+ return false;
cache_lock = &cred->cr_auth->au_credcache->lock;
spin_lock(cache_lock);
- ret = atomic_read(&cred->cr_count) == 0;
- if (ret)
- rpcauth_unhash_cred_locked(cred);
+ ret = rpcauth_unhash_cred_locked(cred);
spin_unlock(cache_lock);
return ret;
}
@@ -388,6 +393,44 @@ void rpcauth_destroy_credlist(struct list_head *head)
}
}
+static void
+rpcauth_lru_add_locked(struct rpc_cred *cred)
+{
+ if (!list_empty(&cred->cr_lru))
+ return;
+ number_cred_unused++;
+ list_add_tail(&cred->cr_lru, &cred_unused);
+}
+
+static void
+rpcauth_lru_add(struct rpc_cred *cred)
+{
+ if (!list_empty(&cred->cr_lru))
+ return;
+ spin_lock(&rpc_credcache_lock);
+ rpcauth_lru_add_locked(cred);
+ spin_unlock(&rpc_credcache_lock);
+}
+
+static void
+rpcauth_lru_remove_locked(struct rpc_cred *cred)
+{
+ if (list_empty(&cred->cr_lru))
+ return;
+ number_cred_unused--;
+ list_del_init(&cred->cr_lru);
+}
+
+static void
+rpcauth_lru_remove(struct rpc_cred *cred)
+{
+ if (list_empty(&cred->cr_lru))
+ return;
+ spin_lock(&rpc_credcache_lock);
+ rpcauth_lru_remove_locked(cred);
+ spin_unlock(&rpc_credcache_lock);
+}
+
/*
* Clear the RPC credential cache, and delete those credentials
* that are not referenced.
@@ -407,13 +450,10 @@ rpcauth_clear_credcache(struct rpc_cred_cache *cache)
head = &cache->hashtable[i];
while (!hlist_empty(head)) {
cred = hlist_entry(head->first, struct rpc_cred, cr_hash);
- get_rpccred(cred);
- if (!list_empty(&cred->cr_lru)) {
- list_del(&cred->cr_lru);
- number_cred_unused--;
- }
- list_add_tail(&cred->cr_lru, &free);
rpcauth_unhash_cred_locked(cred);
+ /* Note: We now hold a reference to cred */
+ rpcauth_lru_remove_locked(cred);
+ list_add_tail(&cred->cr_lru, &free);
}
}
spin_unlock(&cache->lock);
@@ -447,7 +487,6 @@ EXPORT_SYMBOL_GPL(rpcauth_destroy_credcache);
static long
rpcauth_prune_expired(struct list_head *free, int nr_to_scan)
{
- spinlock_t *cache_lock;
struct rpc_cred *cred, *next;
unsigned long expired = jiffies - RPC_AUTH_EXPIRY_MORATORIUM;
long freed = 0;
@@ -456,32 +495,24 @@ rpcauth_prune_expired(struct list_head *free, int nr_to_scan)
if (nr_to_scan-- == 0)
break;
+ if (atomic_read(&cred->cr_count) > 1) {
+ rpcauth_lru_remove_locked(cred);
+ continue;
+ }
/*
* Enforce a 60 second garbage collection moratorium
* Note that the cred_unused list must be time-ordered.
*/
- if (time_in_range(cred->cr_expire, expired, jiffies) &&
- test_bit(RPCAUTH_CRED_HASHED, &cred->cr_flags) != 0) {
- freed = SHRINK_STOP;
- break;
- }
-
- list_del_init(&cred->cr_lru);
- number_cred_unused--;
- freed++;
- if (atomic_read(&cred->cr_count) != 0)
+ if (!time_in_range(cred->cr_expire, expired, jiffies))
+ continue;
+ if (!rpcauth_unhash_cred(cred))
continue;
- cache_lock = &cred->cr_auth->au_credcache->lock;
- spin_lock(cache_lock);
- if (atomic_read(&cred->cr_count) == 0) {
- get_rpccred(cred);
- list_add_tail(&cred->cr_lru, free);
- rpcauth_unhash_cred_locked(cred);
- }
- spin_unlock(cache_lock);
+ rpcauth_lru_remove_locked(cred);
+ freed++;
+ list_add_tail(&cred->cr_lru, free);
}
- return freed;
+ return freed ? freed : SHRINK_STOP;
}
static unsigned long
@@ -595,6 +626,7 @@ rpcauth_lookup_credcache(struct rpc_auth *auth, struct auth_cred * acred,
if (cred == NULL) {
cred = new;
set_bit(RPCAUTH_CRED_HASHED, &cred->cr_flags);
+ atomic_inc(&cred->cr_count);
hlist_add_head_rcu(&cred->cr_hash, &cache->hashtable[nr]);
} else
list_add_tail(&new->cr_lru, &free);
@@ -709,36 +741,29 @@ put_rpccred(struct rpc_cred *cred)
{
if (cred == NULL)
return;
- /* Fast path for unhashed credentials */
- if (test_bit(RPCAUTH_CRED_HASHED, &cred->cr_flags) == 0) {
+ rcu_read_lock();
+ if (atomic_dec_and_test(&cred->cr_count))
+ goto destroy;
+ if (atomic_read(&cred->cr_count) != 1 ||
+ !test_bit(RPCAUTH_CRED_HASHED, &cred->cr_flags))
+ goto out;
+ if (test_bit(RPCAUTH_CRED_UPTODATE, &cred->cr_flags) != 0) {
+ cred->cr_expire = jiffies;
+ rpcauth_lru_add(cred);
+ /* Race breaker */
+ if (unlikely(!test_bit(RPCAUTH_CRED_HASHED, &cred->cr_flags)))
+ rpcauth_lru_remove(cred);
+ } else if (rpcauth_unhash_cred(cred)) {
+ rpcauth_lru_remove(cred);
if (atomic_dec_and_test(&cred->cr_count))
- cred->cr_ops->crdestroy(cred);
- return;
- }
-
- if (!atomic_dec_and_lock(&cred->cr_count, &rpc_credcache_lock))
- return;
- if (!list_empty(&cred->cr_lru)) {
- number_cred_unused--;
- list_del_init(&cred->cr_lru);
- }
- if (test_bit(RPCAUTH_CRED_HASHED, &cred->cr_flags) != 0) {
- if (test_bit(RPCAUTH_CRED_UPTODATE, &cred->cr_flags) != 0) {
- cred->cr_expire = jiffies;
- list_add_tail(&cred->cr_lru, &cred_unused);
- number_cred_unused++;
- goto out_nodestroy;
- }
- if (!rpcauth_unhash_cred(cred)) {
- /* We were hashed and someone looked us up... */
- goto out_nodestroy;
- }
+ goto destroy;
}
- spin_unlock(&rpc_credcache_lock);
- cred->cr_ops->crdestroy(cred);
+out:
+ rcu_read_unlock();
return;
-out_nodestroy:
- spin_unlock(&rpc_credcache_lock);
+destroy:
+ rcu_read_unlock();
+ cred->cr_ops->crdestroy(cred);
}
EXPORT_SYMBOL_GPL(put_rpccred);
@@ -138,6 +138,6 @@ struct rpc_cred null_cred = {
.cr_lru = LIST_HEAD_INIT(null_cred.cr_lru),
.cr_auth = &null_auth,
.cr_ops = &null_credops,
- .cr_count = ATOMIC_INIT(1),
+ .cr_count = ATOMIC_INIT(2),
.cr_flags = 1UL << RPCAUTH_CRED_UPTODATE,
};
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com> --- net/sunrpc/auth.c | 147 ++++++++++++++++++++++++----------------- net/sunrpc/auth_null.c | 2 +- 2 files changed, 87 insertions(+), 62 deletions(-)