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https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2024-09-04 09:59:32 +00:00
SUNRPC: Remove rpc_authflavor_lock in favour of RCU locking
Module removal is RCU safe by design, so we really have no need to lock the auth_flavors[] array. Substitute a lockless scheme to add/remove entries in the array, and then use rcu. Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
This commit is contained in:
parent
1c6c4b740d
commit
4e4c3bef44
1 changed files with 62 additions and 66 deletions
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@ -30,10 +30,9 @@ struct rpc_cred_cache {
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static unsigned int auth_hashbits = RPC_CREDCACHE_DEFAULT_HASHBITS;
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static DEFINE_SPINLOCK(rpc_authflavor_lock);
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static const struct rpc_authops *auth_flavors[RPC_AUTH_MAXFLAVOR] = {
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&authnull_ops, /* AUTH_NULL */
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&authunix_ops, /* AUTH_UNIX */
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static const struct rpc_authops __rcu *auth_flavors[RPC_AUTH_MAXFLAVOR] = {
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[RPC_AUTH_NULL] = (const struct rpc_authops __force __rcu *)&authnull_ops,
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[RPC_AUTH_UNIX] = (const struct rpc_authops __force __rcu *)&authunix_ops,
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NULL, /* others can be loadable modules */
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};
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@ -93,39 +92,65 @@ pseudoflavor_to_flavor(u32 flavor) {
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int
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rpcauth_register(const struct rpc_authops *ops)
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{
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const struct rpc_authops *old;
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rpc_authflavor_t flavor;
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int ret = -EPERM;
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if ((flavor = ops->au_flavor) >= RPC_AUTH_MAXFLAVOR)
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return -EINVAL;
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spin_lock(&rpc_authflavor_lock);
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if (auth_flavors[flavor] == NULL) {
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auth_flavors[flavor] = ops;
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ret = 0;
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}
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spin_unlock(&rpc_authflavor_lock);
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return ret;
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old = cmpxchg((const struct rpc_authops ** __force)&auth_flavors[flavor], NULL, ops);
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if (old == NULL || old == ops)
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return 0;
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return -EPERM;
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}
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EXPORT_SYMBOL_GPL(rpcauth_register);
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int
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rpcauth_unregister(const struct rpc_authops *ops)
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{
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const struct rpc_authops *old;
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rpc_authflavor_t flavor;
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int ret = -EPERM;
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if ((flavor = ops->au_flavor) >= RPC_AUTH_MAXFLAVOR)
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return -EINVAL;
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spin_lock(&rpc_authflavor_lock);
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if (auth_flavors[flavor] == ops) {
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auth_flavors[flavor] = NULL;
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ret = 0;
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}
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spin_unlock(&rpc_authflavor_lock);
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return ret;
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old = cmpxchg((const struct rpc_authops ** __force)&auth_flavors[flavor], ops, NULL);
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if (old == ops || old == NULL)
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return 0;
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return -EPERM;
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}
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EXPORT_SYMBOL_GPL(rpcauth_unregister);
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static const struct rpc_authops *
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rpcauth_get_authops(rpc_authflavor_t flavor)
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{
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const struct rpc_authops *ops;
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if (flavor >= RPC_AUTH_MAXFLAVOR)
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return NULL;
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rcu_read_lock();
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ops = rcu_dereference(auth_flavors[flavor]);
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if (ops == NULL) {
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rcu_read_unlock();
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request_module("rpc-auth-%u", flavor);
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rcu_read_lock();
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ops = rcu_dereference(auth_flavors[flavor]);
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if (ops == NULL)
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goto out;
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}
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if (!try_module_get(ops->owner))
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ops = NULL;
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out:
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rcu_read_unlock();
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return ops;
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}
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static void
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rpcauth_put_authops(const struct rpc_authops *ops)
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{
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module_put(ops->owner);
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}
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/**
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* rpcauth_get_pseudoflavor - check if security flavor is supported
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* @flavor: a security flavor
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@ -138,25 +163,16 @@ EXPORT_SYMBOL_GPL(rpcauth_unregister);
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rpc_authflavor_t
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rpcauth_get_pseudoflavor(rpc_authflavor_t flavor, struct rpcsec_gss_info *info)
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{
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const struct rpc_authops *ops;
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const struct rpc_authops *ops = rpcauth_get_authops(flavor);
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rpc_authflavor_t pseudoflavor;
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ops = auth_flavors[flavor];
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if (ops == NULL)
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request_module("rpc-auth-%u", flavor);
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spin_lock(&rpc_authflavor_lock);
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ops = auth_flavors[flavor];
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if (ops == NULL || !try_module_get(ops->owner)) {
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spin_unlock(&rpc_authflavor_lock);
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if (!ops)
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return RPC_AUTH_MAXFLAVOR;
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}
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spin_unlock(&rpc_authflavor_lock);
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pseudoflavor = flavor;
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if (ops->info2flavor != NULL)
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pseudoflavor = ops->info2flavor(info);
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module_put(ops->owner);
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rpcauth_put_authops(ops);
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return pseudoflavor;
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}
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EXPORT_SYMBOL_GPL(rpcauth_get_pseudoflavor);
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@ -176,25 +192,15 @@ rpcauth_get_gssinfo(rpc_authflavor_t pseudoflavor, struct rpcsec_gss_info *info)
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const struct rpc_authops *ops;
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int result;
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if (flavor >= RPC_AUTH_MAXFLAVOR)
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return -EINVAL;
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ops = auth_flavors[flavor];
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ops = rpcauth_get_authops(flavor);
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if (ops == NULL)
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request_module("rpc-auth-%u", flavor);
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spin_lock(&rpc_authflavor_lock);
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ops = auth_flavors[flavor];
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if (ops == NULL || !try_module_get(ops->owner)) {
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spin_unlock(&rpc_authflavor_lock);
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return -ENOENT;
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}
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spin_unlock(&rpc_authflavor_lock);
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result = -ENOENT;
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if (ops->flavor2info != NULL)
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result = ops->flavor2info(pseudoflavor, info);
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module_put(ops->owner);
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rpcauth_put_authops(ops);
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return result;
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}
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EXPORT_SYMBOL_GPL(rpcauth_get_gssinfo);
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@ -212,15 +218,13 @@ EXPORT_SYMBOL_GPL(rpcauth_get_gssinfo);
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int
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rpcauth_list_flavors(rpc_authflavor_t *array, int size)
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{
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rpc_authflavor_t flavor;
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int result = 0;
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const struct rpc_authops *ops;
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rpc_authflavor_t flavor, pseudos[4];
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int i, len, result = 0;
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spin_lock(&rpc_authflavor_lock);
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rcu_read_lock();
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for (flavor = 0; flavor < RPC_AUTH_MAXFLAVOR; flavor++) {
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const struct rpc_authops *ops = auth_flavors[flavor];
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rpc_authflavor_t pseudos[4];
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int i, len;
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ops = rcu_dereference(auth_flavors[flavor]);
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if (result >= size) {
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result = -ENOMEM;
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break;
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@ -245,7 +249,7 @@ rpcauth_list_flavors(rpc_authflavor_t *array, int size)
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array[result++] = pseudos[i];
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}
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}
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spin_unlock(&rpc_authflavor_lock);
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rcu_read_unlock();
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dprintk("RPC: %s returns %d\n", __func__, result);
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return result;
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@ -255,25 +259,17 @@ EXPORT_SYMBOL_GPL(rpcauth_list_flavors);
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struct rpc_auth *
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rpcauth_create(const struct rpc_auth_create_args *args, struct rpc_clnt *clnt)
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{
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struct rpc_auth *auth;
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struct rpc_auth *auth = ERR_PTR(-EINVAL);
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const struct rpc_authops *ops;
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u32 flavor = pseudoflavor_to_flavor(args->pseudoflavor);
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u32 flavor = pseudoflavor_to_flavor(args->pseudoflavor);
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auth = ERR_PTR(-EINVAL);
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if (flavor >= RPC_AUTH_MAXFLAVOR)
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ops = rpcauth_get_authops(flavor);
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if (ops == NULL)
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goto out;
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if ((ops = auth_flavors[flavor]) == NULL)
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request_module("rpc-auth-%u", flavor);
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spin_lock(&rpc_authflavor_lock);
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ops = auth_flavors[flavor];
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if (ops == NULL || !try_module_get(ops->owner)) {
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spin_unlock(&rpc_authflavor_lock);
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goto out;
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}
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spin_unlock(&rpc_authflavor_lock);
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auth = ops->create(args, clnt);
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module_put(ops->owner);
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rpcauth_put_authops(ops);
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if (IS_ERR(auth))
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return auth;
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if (clnt->cl_auth)
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