Commit 30382d6c authored by Trond Myklebust's avatar Trond Myklebust Committed by J. Bruce Fields
Browse files

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: default avatarTrond Myklebust <trond.myklebust@hammerspace.com>
Signed-off-by: default avatarJ. Bruce Fields <bfields@redhat.com>
parent 7d20b6a2

net/sunrpc/svcauth.c

+34 −18
Original line number Diff line number Diff line
@@ -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;



	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);