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: J. Bruce Fields <bfields@redhat.com>
diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
index f1e5ec6..ad2bfa6 100644
--- a/fs/nfsd/nfs4state.c
+++ b/fs/nfsd/nfs4state.c
@@ -673,16 +673,17 @@
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 @@
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 @@
{
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 @@
}
__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;
}
diff --git a/include/linux/sunrpc/svc_xprt.h b/include/linux/sunrpc/svc_xprt.h
index bbdb680..aea0d438 100644
--- a/include/linux/sunrpc/svc_xprt.h
+++ b/include/linux/sunrpc/svc_xprt.h
@@ -82,13 +82,6 @@
struct net *xpt_net;
};
-static inline void register_xpt_user(struct svc_xprt *xpt, struct svc_xpt_user *u)
-{
- spin_lock(&xpt->xpt_lock);
- list_add(&u->list, &xpt->xpt_users);
- spin_unlock(&xpt->xpt_lock);
-}
-
static inline void unregister_xpt_user(struct svc_xprt *xpt, struct svc_xpt_user *u)
{
spin_lock(&xpt->xpt_lock);
@@ -96,6 +89,23 @@
spin_unlock(&xpt->xpt_lock);
}
+static inline int register_xpt_user(struct svc_xprt *xpt, struct svc_xpt_user *u)
+{
+ spin_lock(&xpt->xpt_lock);
+ 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 *);
void svc_unreg_xprt_class(struct svc_xprt_class *);
void svc_xprt_init(struct svc_xprt_class *, struct svc_xprt *,