[Xen-changelog] [linux-2.6.18-xen] netfront accel: Better watch handling across suspend/resume

["Xen patchbot-linux-2.6.18-xen" <patchbot-linux-2.6.18-xen@xxxxxxxxxxxxxxxxxxx>]

# HG changeset patch
# User Keir Fraser <keir.fraser@xxxxxxxxxx>
# Date 1239096570 -3600
# Node ID e5d3f2fa3428ca1d3ee265647b60239509cd798c
# Parent  950b9eb2766128f85adf52d5aabcd15eb8c77dc0
netfront accel: Better watch handling across suspend/resume

Signed-off-by: Kieran Mansley <kmansley@xxxxxxxxxxxxxx>
---
 drivers/xen/netfront/accel.c |   43 ++++++++++++++++++++++++++++---------------
 1 files changed, 28 insertions(+), 15 deletions(-)

diff -r 950b9eb27661 -r e5d3f2fa3428 drivers/xen/netfront/accel.c
--- a/drivers/xen/netfront/accel.c      Mon Apr 06 13:51:20 2009 +0100
+++ b/drivers/xen/netfront/accel.c      Tue Apr 07 10:29:30 2009 +0100
@@ -50,6 +50,8 @@ static int netfront_load_accelerator(str
 static int netfront_load_accelerator(struct netfront_info *np, 
                                     struct xenbus_device *dev, 
                                     const char *frontend);
+
+static void netfront_accelerator_remove_watch(struct netfront_info *np);
 
 /*
  * List of all netfront accelerator plugin modules available.  Each
@@ -164,8 +166,11 @@ void netfront_accelerator_add_watch(stru
 {
        int err;
        
-       /* Check we're not trying to overwrite an existing watch */
-       BUG_ON(np->accel_vif_state.accel_watch.node != NULL);
+       /* 
+        * If old watch exists, e.g. from before suspend/resume,
+        * remove it now 
+        */
+       netfront_accelerator_remove_watch(np);
 
        /* Get a watch on the accelerator plugin */
        err = xenbus_watch_path2(np->xbdev, np->xbdev->otherend, 
@@ -180,6 +185,19 @@ void netfront_accelerator_add_watch(stru
 }
 
 
+static void 
+netfront_accelerator_purge_watch(struct netfront_accel_vif_state *vif_state)
+{
+       flush_workqueue(accel_watch_workqueue);
+
+       /* Clean up any state left from watch */
+       if (vif_state->accel_frontend != NULL) {
+               kfree(vif_state->accel_frontend);
+               vif_state->accel_frontend = NULL;
+       }
+}
+
+
 static
 void netfront_accelerator_remove_watch(struct netfront_info *np)
 {
@@ -191,13 +209,7 @@ void netfront_accelerator_remove_watch(s
                kfree(vif_state->accel_watch.node);
                vif_state->accel_watch.node = NULL;
 
-               flush_workqueue(accel_watch_workqueue);
-
-               /* Clean up any state left from watch */
-               if (vif_state->accel_frontend != NULL) {
-                       kfree(vif_state->accel_frontend);
-                       vif_state->accel_frontend = NULL;
-               }
+               netfront_accelerator_purge_watch(vif_state);
        }       
 }
 
@@ -670,8 +682,6 @@ int netfront_accelerator_suspend(struct 
 {
        int rc = 0;
        
-       netfront_accelerator_remove_watch(np);
-
        mutex_lock(&accelerator_mutex);
 
        /* Check that we've got a device that was accelerated */
@@ -692,13 +702,16 @@ int netfront_accelerator_suspend_cancel(
 int netfront_accelerator_suspend_cancel(struct netfront_info *np,
                                        struct xenbus_device *dev)
 {
+       netfront_accelerator_purge_watch(&np->accel_vif_state);
+
        /* 
-        * Setting the watch will cause it to fire and probe the
-        * accelerator, so no need to call accelerator_probe_new_vif()
-        * directly here
+        * Gratuitously fire the watch handler to reinstate the
+        * configured accelerator
         */
        if (dev->state == XenbusStateConnected)
-               netfront_accelerator_add_watch(np);
+               queue_work(accel_watch_workqueue, 
+                          &np->accel_vif_state.accel_work);
+
        return 0;
 }
 

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