From 21b75b019983dfa5c2dda588f4b60b4ca69844a4 Mon Sep 17 00:00:00 2001 From: "J. Bruce Fields" Date: Tue, 26 Oct 2010 10:07:17 -0400 Subject: 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 --- fs/nfsd/nfs4state.c | 16 ++++++++++++---- include/linux/sunrpc/svc_xprt.h | 18 ++++++++++++++---- 2 files changed, 26 insertions(+), 8 deletions(-) diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c index f1e5ec6b510..ad2bfa68d53 100644 --- a/fs/nfsd/nfs4state.c +++ b/fs/nfsd/nfs4state.c @@ -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; } diff --git a/include/linux/sunrpc/svc_xprt.h b/include/linux/sunrpc/svc_xprt.h index bbdb680ffbe..aea0d438e3c 100644 --- a/include/linux/sunrpc/svc_xprt.h +++ b/include/linux/sunrpc/svc_xprt.h @@ -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 *); -- cgit v1.2.3-70-g09d2