diff options
| author | NeilBrown <neilb@suse.de> | 2014-07-14 11:28:20 +1000 |
|---|---|---|
| committer | Trond Myklebust <trond.myklebust@primarydata.com> | 2014-08-03 17:14:12 -0400 |
| commit | bd95608053b7f7813351b0defc0e3e7ef8cf2803 (patch) | |
| tree | fde08b1ecc2c4aedd30a68244ca502ce5f81f0fe /net/sunrpc | |
| parent | d51ac1a8e9b86b2d17d349bb256869cab6522787 (diff) | |
sunrpc/auth: allow lockless (rcu) lookup of credential cache.
The new flag RPCAUTH_LOOKUP_RCU to credential lookup avoids locking,
does not take a reference on the returned credential, and returns
-ECHILD if a simple lookup was not possible.
The returned value can only be used within an rcu_read_lock protected
region.
The main user of this is the new rpc_lookup_cred_nonblock() which
returns a pointer to the current credential which is only rcu-safe (no
ref-count held), and might return -ECHILD if allocation was required.
Signed-off-by: NeilBrown <neilb@suse.de>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
Diffstat (limited to 'net/sunrpc')
| -rw-r--r-- | net/sunrpc/auth.c | 17 | ||||
| -rw-r--r-- | net/sunrpc/auth_generic.c | 6 | ||||
| -rw-r--r-- | net/sunrpc/auth_null.c | 2 |
3 files changed, 23 insertions, 2 deletions
diff --git a/net/sunrpc/auth.c b/net/sunrpc/auth.c index 360decdddc78..24fcbd23ae6c 100644 --- a/net/sunrpc/auth.c +++ b/net/sunrpc/auth.c @@ -557,6 +557,12 @@ rpcauth_lookup_credcache(struct rpc_auth *auth, struct auth_cred * acred, hlist_for_each_entry_rcu(entry, &cache->hashtable[nr], cr_hash) { if (!entry->cr_ops->crmatch(acred, entry, flags)) continue; + if (flags & RPCAUTH_LOOKUP_RCU) { + if (test_bit(RPCAUTH_CRED_HASHED, &entry->cr_flags) && + !test_bit(RPCAUTH_CRED_NEW, &entry->cr_flags)) + cred = entry; + break; + } spin_lock(&cache->lock); if (test_bit(RPCAUTH_CRED_HASHED, &entry->cr_flags) == 0) { spin_unlock(&cache->lock); @@ -571,6 +577,9 @@ rpcauth_lookup_credcache(struct rpc_auth *auth, struct auth_cred * acred, if (cred != NULL) goto found; + if (flags & RPCAUTH_LOOKUP_RCU) + return ERR_PTR(-ECHILD); + new = auth->au_ops->crcreate(auth, acred, flags); if (IS_ERR(new)) { cred = new; @@ -621,10 +630,14 @@ rpcauth_lookupcred(struct rpc_auth *auth, int flags) memset(&acred, 0, sizeof(acred)); acred.uid = cred->fsuid; acred.gid = cred->fsgid; - acred.group_info = get_group_info(((struct cred *)cred)->group_info); + if (flags & RPCAUTH_LOOKUP_RCU) + acred.group_info = rcu_dereference(cred->group_info); + else + acred.group_info = get_group_info(((struct cred *)cred)->group_info); ret = auth->au_ops->lookup_cred(auth, &acred, flags); - put_group_info(acred.group_info); + if (!(flags & RPCAUTH_LOOKUP_RCU)) + put_group_info(acred.group_info); return ret; } EXPORT_SYMBOL_GPL(rpcauth_lookupcred); diff --git a/net/sunrpc/auth_generic.c b/net/sunrpc/auth_generic.c index ed04869b2d4f..6f6b829c9e8e 100644 --- a/net/sunrpc/auth_generic.c +++ b/net/sunrpc/auth_generic.c @@ -38,6 +38,12 @@ struct rpc_cred *rpc_lookup_cred(void) } EXPORT_SYMBOL_GPL(rpc_lookup_cred); +struct rpc_cred *rpc_lookup_cred_nonblock(void) +{ + return rpcauth_lookupcred(&generic_auth, RPCAUTH_LOOKUP_RCU); +} +EXPORT_SYMBOL_GPL(rpc_lookup_cred_nonblock); + /* * Public call interface for looking up machine creds. */ diff --git a/net/sunrpc/auth_null.c b/net/sunrpc/auth_null.c index f0ebe07978a2..712c123e04e9 100644 --- a/net/sunrpc/auth_null.c +++ b/net/sunrpc/auth_null.c @@ -35,6 +35,8 @@ nul_destroy(struct rpc_auth *auth) static struct rpc_cred * nul_lookup_cred(struct rpc_auth *auth, struct auth_cred *acred, int flags) { + if (flags & RPCAUTH_LOOKUP_RCU) + return &null_cred; return get_rpccred(&null_cred); } |