[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>

diff --git a/fs/dlm/lowcomms-tcp.c b/fs/dlm/lowcomms-tcp.c
index 18ade44287e7d54a4e82b6b26da3ceda2e0712d5..f1efd17b2614b28cc0be7aff2e5f1fff8f65463f 100644 (file)
--- 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;