[PATCH] knfsd: fix recently introduced problem with shutting down a busy NFS server

When the last thread of nfsd exits, it shuts down all related sockets.  It
currently uses svc_close_socket to do this, but that only is immediately
effective if the socket is not SK_BUSY.

If the socket is busy - i.e.  if a request has arrived that has not yet been
processes - svc_close_socket is not effective and the shutdown process spins.

So create a new svc_force_close_socket which removes the SK_BUSY flag is set
and then calls svc_close_socket.

Also change some open-codes loops in svc_destroy to use
list_for_each_entry_safe.

Signed-off-by: Neil Brown <neilb@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 15 insertions, 1 deletions

diff --git a/net/sunrpc/svcsock.c b/net/sunrpc/svcsock.c
index e957ce55fd91..f6e1eb1ea720 100644
--- a/net/sunrpc/svcsock.c
+++ b/net/sunrpc/svcsock.c
@@ -82,6 +82,7 @@ static void		svc_delete_socket(struct svc_sock *svsk);
 static void             svc_udp_data_ready(struct sock *, int);
 static int              svc_udp_recvfrom(struct svc_rqst *);
 static int              svc_udp_sendto(struct svc_rqst *);
+static void             svc_close_socket(struct svc_sock *svsk);
 
 static struct svc_deferred_req *svc_deferred_dequeue(struct svc_sock *svsk);
 static int svc_deferred_recv(struct svc_rqst *rqstp);
@@ -1787,7 +1788,7 @@ svc_delete_socket(struct svc_sock *svsk)
         spin_unlock_bh(&serv->sv_lock);
 }
 
-void svc_close_socket(struct svc_sock *svsk)
+static void svc_close_socket(struct svc_sock *svsk)
 {
         set_bit(SK_CLOSE, &svsk->sk_flags);
         if (test_and_set_bit(SK_BUSY, &svsk->sk_flags))
@@ -1800,6 +1801,19 @@ void svc_close_socket(struct svc_sock *svsk)
         svc_sock_put(svsk);
 }
 
+void svc_force_close_socket(struct svc_sock *svsk)
+{
+        set_bit(SK_CLOSE, &svsk->sk_flags);
+        if (test_bit(SK_BUSY, &svsk->sk_flags)) {
+                /* Waiting to be processed, but no threads left,
+                 * So just remove it from the waiting list
+                 */
+                list_del_init(&svsk->sk_ready);
+                clear_bit(SK_BUSY, &svsk->sk_flags);
+        }
+        svc_close_socket(svsk);
+}
+
 /**
  * svc_makesock - Make a socket for nfsd and lockd
  * @serv: RPC server structure