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From:   NeilBrown <neilb@suse.de>
To:     Chuck Lever <chuck.lever@oracle.com>,
        Jeff Layton <jlayton@kernel.org>
Cc:     linux-nfs@vger.kernel.org, Olga Kornievskaia <kolga@netapp.com>,
        Dai Ngo <Dai.Ngo@oracle.com>, Tom Talpey <tom@talpey.com>
Subject: [PATCH 1/5] nfsd: call nfsd_last_thread() before final nfsd_put()
Date:   Mon, 30 Oct 2023 12:08:34 +1100
Message-ID: <20231030011247.9794-2-neilb@suse.de>
In-Reply-To: <20231030011247.9794-1-neilb@suse.de>
References: <20231030011247.9794-1-neilb@suse.de>
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If write_ports_addfd or write_ports_addxprt fail, they call nfsD_put()
without calling nfsd_last_thread().  This leaves nn->nfsd_serv pointing
to a structure that has been freed.

So export nfsd_last_thread() and call it when the nfsd_serv is about to
be destroy.

Signed-off-by: NeilBrown <neilb@suse.de>
---
 fs/nfsd/nfsctl.c | 9 +++++++--
 fs/nfsd/nfsd.h   | 1 +
 fs/nfsd/nfssvc.c | 2 +-
 3 files changed, 9 insertions(+), 3 deletions(-)

diff --git a/fs/nfsd/nfsctl.c b/fs/nfsd/nfsctl.c
index 739ed5bf71cd..79efb1075f38 100644
--- a/fs/nfsd/nfsctl.c
+++ b/fs/nfsd/nfsctl.c
@@ -705,8 +705,10 @@ static ssize_t __write_ports_addfd(char *buf, struct net *net, const struct cred
 
 	err = svc_addsock(nn->nfsd_serv, net, fd, buf, SIMPLE_TRANSACTION_LIMIT, cred);
 
-	if (err >= 0 &&
-	    !nn->nfsd_serv->sv_nrthreads && !xchg(&nn->keep_active, 1))
+	if (err < 0 && !nn->nfsd_serv->sv_nrthreads && !nn->keep_active)
+		nfsd_last_thread(net);
+	else if (err >= 0 &&
+		 !nn->nfsd_serv->sv_nrthreads && !xchg(&nn->keep_active, 1))
 		svc_get(nn->nfsd_serv);
 
 	nfsd_put(net);
@@ -757,6 +759,9 @@ static ssize_t __write_ports_addxprt(char *buf, struct net *net, const struct cr
 		svc_xprt_put(xprt);
 	}
 out_err:
+	if (!nn->nfsd_serv->sv_nrthreads && !nn->keep_active)
+		nfsd_last_thread(net);
+
 	nfsd_put(net);
 	return err;
 }
diff --git a/fs/nfsd/nfsd.h b/fs/nfsd/nfsd.h
index f5ff42f41ee7..3286ffacbc56 100644
--- a/fs/nfsd/nfsd.h
+++ b/fs/nfsd/nfsd.h
@@ -155,6 +155,7 @@ int nfsd_vers(struct nfsd_net *nn, int vers, enum vers_op change);
 int nfsd_minorversion(struct nfsd_net *nn, u32 minorversion, enum vers_op change);
 void nfsd_reset_versions(struct nfsd_net *nn);
 int nfsd_create_serv(struct net *net);
+void nfsd_last_thread(struct net *net);
 
 extern int nfsd_max_blksize;
 
diff --git a/fs/nfsd/nfssvc.c b/fs/nfsd/nfssvc.c
index d6122bb2d167..6c968c02cc29 100644
--- a/fs/nfsd/nfssvc.c
+++ b/fs/nfsd/nfssvc.c
@@ -542,7 +542,7 @@ static struct notifier_block nfsd_inet6addr_notifier = {
 /* Only used under nfsd_mutex, so this atomic may be overkill: */
 static atomic_t nfsd_notifier_refcount = ATOMIC_INIT(0);
 
-static void nfsd_last_thread(struct net *net)
+void nfsd_last_thread(struct net *net)
 {
 	struct nfsd_net *nn = net_generic(net, nfsd_net_id);
 	struct svc_serv *serv = nn->nfsd_serv;
-- 
2.42.0