Commit 21b75b01 authored by J. Bruce Fields's avatar J. Bruce Fields
Browse files

nfsd4: fix 4.1 connection registration race 



If a connection is closed just after a sequence or create_session
is sent over it, we could end up trying to register a callback that will
never get called since the xprt is already marked dead.

Signed-off-by: default avatarJ. Bruce Fields <bfields@redhat.com>
parent c8ddb271

fs/nfsd/nfs4state.c

+12 −4
Original line number Diff line number Diff line
@@ -673,16 +673,17 @@ static void nfsd4_hash_conn(struct nfsd4_conn *conn, struct nfsd4_session *ses) 
	spin_unlock(&clp->cl_lock);

}



static void nfsd4_register_conn(struct nfsd4_conn *conn)

static int nfsd4_register_conn(struct nfsd4_conn *conn)

{

	conn->cn_xpt_user.callback = nfsd4_conn_lost;

	register_xpt_user(conn->cn_xprt, &conn->cn_xpt_user);

	return register_xpt_user(conn->cn_xprt, &conn->cn_xpt_user);

}



static __be32 nfsd4_new_conn(struct svc_rqst *rqstp, struct nfsd4_session *ses)

{

	struct nfsd4_conn *conn;

	u32 flags = NFS4_CDFC4_FORE;

	int ret;



	if (ses->se_flags & SESSION4_BACK_CHAN)

		flags |= NFS4_CDFC4_BACK;
@@ -690,7 +691,10 @@ static __be32 nfsd4_new_conn(struct svc_rqst *rqstp, struct nfsd4_session *ses) 
	if (!conn)

		return nfserr_jukebox;

	nfsd4_hash_conn(conn, ses);

	nfsd4_register_conn(conn);

	ret = nfsd4_register_conn(conn);

	if (ret)

		/* oops; xprt is already down: */

		nfsd4_conn_lost(&conn->cn_xpt_user);

	return nfs_ok;

}
@@ -1644,6 +1648,7 @@ static void nfsd4_sequence_check_conn(struct nfsd4_conn *new, struct nfsd4_sessi 
{

	struct nfs4_client *clp = ses->se_client;

	struct nfsd4_conn *c;

	int ret;



	spin_lock(&clp->cl_lock);

	c = __nfsd4_find_conn(new->cn_xprt, ses);
@@ -1654,7 +1659,10 @@ static void nfsd4_sequence_check_conn(struct nfsd4_conn *new, struct nfsd4_sessi 
	}

	__nfsd4_hash_conn(new, ses);

	spin_unlock(&clp->cl_lock);

	nfsd4_register_conn(new);

	ret = nfsd4_register_conn(new);

	if (ret)

		/* oops; xprt is already down: */

		nfsd4_conn_lost(&new->cn_xpt_user);

	return;

}

include/linux/sunrpc/svc_xprt.h

+14 −4
Original line number Diff line number Diff line
@@ -82,18 +82,28 @@ struct svc_xprt { 
	struct net		*xpt_net;

};



static inline void register_xpt_user(struct svc_xprt *xpt, struct svc_xpt_user *u)

static inline void unregister_xpt_user(struct svc_xprt *xpt, struct svc_xpt_user *u)

{

	spin_lock(&xpt->xpt_lock);

	list_add(&u->list, &xpt->xpt_users);

	list_del_init(&u->list);

	spin_unlock(&xpt->xpt_lock);

}



static inline void unregister_xpt_user(struct svc_xprt *xpt, struct svc_xpt_user *u)

static inline int register_xpt_user(struct svc_xprt *xpt, struct svc_xpt_user *u)

{

	spin_lock(&xpt->xpt_lock);

	list_del_init(&u->list);

	if (test_bit(XPT_CLOSE, &xpt->xpt_flags)) {

		/*

		 * The connection is about to be deleted soon (or,

		 * worse, may already be deleted--in which case we've

		 * already notified the xpt_users).

		 */

		spin_unlock(&xpt->xpt_lock);

		return -ENOTCONN;

	}

	list_add(&u->list, &xpt->xpt_users);

	spin_unlock(&xpt->xpt_lock);

	return 0;

}



int	svc_reg_xprt_class(struct svc_xprt_class *);