[DLM] fix softlockup in dlm_recv

This patch stops the dlm_recv workqueue from busy-waiting when a node
disconnects. This can cause soft lockup errors on debug systems and bad
performance generally.

Signed-Off-By: Patrick Caulfield <pcaulfie@redhat.com>
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>

1 files changed, 9 insertions, 6 deletions

diff --git a/fs/dlm/lowcomms-tcp.c b/fs/dlm/lowcomms-tcp.c
index 18ade44287e7..f1efd17b2614 100644
--- a/fs/dlm/lowcomms-tcp.c
+++ b/fs/dlm/lowcomms-tcp.c
@@ -2,7 +2,7 @@
 *******************************************************************************
 **
 **  Copyright (C) Sistina Software, Inc.  1997-2003  All rights reserved.
-**  Copyright (C) 2004-2006 Red Hat, Inc.  All rights reserved.
+**  Copyright (C) 2004-2007 Red Hat, Inc.  All rights reserved.
 **
 **  This copyrighted material is made available to anyone wishing to use,
 **  modify, copy, or redistribute it subject to the terms and conditions
@@ -109,7 +109,6 @@ struct connection {
         struct page *rx_page;
         struct cbuf cb;
         int retries;
-        atomic_t waiting_requests;
 #define MAX_CONNECT_RETRIES 3
         struct connection *othercon;
         struct work_struct rwork; /* Receive workqueue */
@@ -278,8 +277,11 @@ static int receive_from_sock(struct connection *con)
 
         mutex_lock(&con->sock_mutex);
 
-        if (con->sock == NULL)
-                goto out;
+        if (con->sock == NULL) {
+                ret = -EAGAIN;
+                goto out_close;
+        }
+
         if (con->rx_page == NULL) {
                 /*
                  * This doesn't need to be atomic, but I think it should
@@ -352,7 +354,6 @@ static int receive_from_sock(struct connection *con)
                 con->rx_page = NULL;
         }
 
-out:
         if (call_again_soon)
                 goto out_resched;
         mutex_unlock(&con->sock_mutex);
@@ -370,6 +371,9 @@ out_close:
                 close_connection(con, false);
                 /* Reconnect when there is something to send */
         }
+        /* Don't return success if we really got EOF */
+        if (ret == 0)
+                ret = -EAGAIN;
 
         return ret;
 }
@@ -847,7 +851,6 @@ int dlm_lowcomms_close(int nodeid)
         if (con) {
                 clean_one_writequeue(con);
                 close_connection(con, true);
-                atomic_set(&con->waiting_requests, 0);
         }
         return 0;