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authorTrond Myklebust <trondmy@gmail.com>2018-10-01 17:41:43 +0300
committerJ. Bruce Fields <bfields@redhat.com>2018-10-03 18:32:59 +0300
commit30382d6ce593f863292cd7c026a79077c4e7280f (patch)
tree27c3df5c521a0e393232006c7b1d7288f02a3431 /net/sunrpc/svcauth.c
parent7d20b6a2728fe3ea9fa8f4fc49cd438fcc781dd1 (diff)
downloadlinux-30382d6ce593f863292cd7c026a79077c4e7280f.tar.xz
SUNRPC: Remove the server 'authtab_lock' and just use RCU
Module removal is RCU safe by design, so we really have no need to lock the 'authtab[]' array. Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com> Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Diffstat (limited to 'net/sunrpc/svcauth.c')
-rw-r--r--net/sunrpc/svcauth.c52
1 files changed, 34 insertions, 18 deletions
diff --git a/net/sunrpc/svcauth.c b/net/sunrpc/svcauth.c
index bb8db3cb8032..f83443856cd1 100644
--- a/net/sunrpc/svcauth.c
+++ b/net/sunrpc/svcauth.c
@@ -27,12 +27,32 @@
extern struct auth_ops svcauth_null;
extern struct auth_ops svcauth_unix;
-static DEFINE_SPINLOCK(authtab_lock);
-static struct auth_ops *authtab[RPC_AUTH_MAXFLAVOR] = {
- [0] = &svcauth_null,
- [1] = &svcauth_unix,
+static struct auth_ops __rcu *authtab[RPC_AUTH_MAXFLAVOR] = {
+ [RPC_AUTH_NULL] = (struct auth_ops __force __rcu *)&svcauth_null,
+ [RPC_AUTH_UNIX] = (struct auth_ops __force __rcu *)&svcauth_unix,
};
+static struct auth_ops *
+svc_get_auth_ops(rpc_authflavor_t flavor)
+{
+ struct auth_ops *aops;
+
+ if (flavor >= RPC_AUTH_MAXFLAVOR)
+ return NULL;
+ rcu_read_lock();
+ aops = rcu_dereference(authtab[flavor]);
+ if (aops != NULL && !try_module_get(aops->owner))
+ aops = NULL;
+ rcu_read_unlock();
+ return aops;
+}
+
+static void
+svc_put_auth_ops(struct auth_ops *aops)
+{
+ module_put(aops->owner);
+}
+
int
svc_authenticate(struct svc_rqst *rqstp, __be32 *authp)
{
@@ -45,14 +65,11 @@ svc_authenticate(struct svc_rqst *rqstp, __be32 *authp)
dprintk("svc: svc_authenticate (%d)\n", flavor);
- spin_lock(&authtab_lock);
- if (flavor >= RPC_AUTH_MAXFLAVOR || !(aops = authtab[flavor]) ||
- !try_module_get(aops->owner)) {
- spin_unlock(&authtab_lock);
+ aops = svc_get_auth_ops(flavor);
+ if (aops == NULL) {
*authp = rpc_autherr_badcred;
return SVC_DENIED;
}
- spin_unlock(&authtab_lock);
rqstp->rq_auth_slack = 0;
init_svc_cred(&rqstp->rq_cred);
@@ -82,7 +99,7 @@ int svc_authorise(struct svc_rqst *rqstp)
if (aops) {
rv = aops->release(rqstp);
- module_put(aops->owner);
+ svc_put_auth_ops(aops);
}
return rv;
}
@@ -90,13 +107,14 @@ int svc_authorise(struct svc_rqst *rqstp)
int
svc_auth_register(rpc_authflavor_t flavor, struct auth_ops *aops)
{
+ struct auth_ops *old;
int rv = -EINVAL;
- spin_lock(&authtab_lock);
- if (flavor < RPC_AUTH_MAXFLAVOR && authtab[flavor] == NULL) {
- authtab[flavor] = aops;
- rv = 0;
+
+ if (flavor < RPC_AUTH_MAXFLAVOR) {
+ old = cmpxchg((struct auth_ops ** __force)&authtab[flavor], NULL, aops);
+ if (old == NULL || old == aops)
+ rv = 0;
}
- spin_unlock(&authtab_lock);
return rv;
}
EXPORT_SYMBOL_GPL(svc_auth_register);
@@ -104,10 +122,8 @@ EXPORT_SYMBOL_GPL(svc_auth_register);
void
svc_auth_unregister(rpc_authflavor_t flavor)
{
- spin_lock(&authtab_lock);
if (flavor < RPC_AUTH_MAXFLAVOR)
- authtab[flavor] = NULL;
- spin_unlock(&authtab_lock);
+ rcu_assign_pointer(authtab[flavor], NULL);
}
EXPORT_SYMBOL_GPL(svc_auth_unregister);