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/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 *,