Patch "nfsd: call nfsd_last_thread() before final nfsd_put()" has been added to the 5.10-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    nfsd: call nfsd_last_thread() before final nfsd_put()

to the 5.10-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     nfsd-call-nfsd_last_thread-before-final-nfsd_put.patch
and it can be found in the queue-5.10 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit 0edd6f3e2c2d415d6f5b8d9ed56a67f747fd8832
Author: NeilBrown <neilb@xxxxxxx>
Date:   Fri Dec 15 11:56:31 2023 +1100

    nfsd: call nfsd_last_thread() before final nfsd_put()
    
    [ Upstream commit 2a501f55cd641eb4d3c16a2eab0d678693fac663 ]
    
    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 remove 'static' from nfsd_last_thread() and call it when the
    nfsd_serv is about to be destroyed.
    
    Fixes: ec52361df99b ("SUNRPC: stop using ->sv_nrthreads as a refcount")
    Signed-off-by: NeilBrown <neilb@xxxxxxx>
    Reviewed-by: Jeff Layton <jlayton@xxxxxxxxxx>
    Cc: <stable@xxxxxxxxxxxxxxx>
    Signed-off-by: Chuck Lever <chuck.lever@xxxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/fs/nfsd/nfsctl.c b/fs/nfsd/nfsctl.c
index 76a60e7a75097..eec442edb6556 100644
--- a/fs/nfsd/nfsctl.c
+++ b/fs/nfsd/nfsctl.c
@@ -720,8 +720,10 @@ 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);
@@ -771,6 +773,9 @@ 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 867dcfd64d426..3796015dc7656 100644
--- a/fs/nfsd/nfsd.h
+++ b/fs/nfsd/nfsd.h
@@ -138,6 +138,7 @@ 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 2a1dd580dfb94..3d4fd40c987bd 100644
--- a/fs/nfsd/nfssvc.c
+++ b/fs/nfsd/nfssvc.c
@@ -529,7 +529,7 @@ 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;