Properly handle suspend/resume events in the Xen device

framework.

Sponsored by:	BQ Internet

sys/xen/xenbus/xenbusb.c:
	o In xenbusb_resume(), publish the state transition of the
	  resuming device into XenbusStateIntiailising so that the
	  remote peer can see it.  Recording the state locally is
	  not sufficient to trigger a re-connect sequence.
	o In xenbusb_resume(), defer new-bus resume processing until
	  after the remote peer's XenStore address has been updated.
	  The drivers may need to refer to this information during
	  resume processing.

sys/xen/xenbus/xenbusb_back.c:
sys/xen/xenbus/xenbusb_front.c:
	Register xenbusb_resume() rather than bus_generic_resume()
	as the handler for device_resume events.

sys/xen/xenstore/xenstore.c:
	o Fix grammer in a comment.
	o In xs_suspend(), pass suspend events on to the child
	  devices (e.g. xenbusb_front/back, that are attached
	  to the XenStore.

Approved by:	re
MFC after:	1 week

4 files changed, 18 insertions, 9 deletions

diff --git a/sys/xen/xenbus/xenbusb.c b/sys/xen/xenbus/xenbusb.c
index cc519c5..3e2d56f 100644
--- a/sys/xen/xenbus/xenbusb.c
+++ b/sys/xen/xenbus/xenbusb.c
@@ -773,7 +773,7 @@ xenbusb_resume(device_t dev)
 			ivars = device_get_ivars(kids[i]);
 
 			xs_unregister_watch(&ivars->xd_otherend_watch);
-			ivars->xd_state = XenbusStateInitialising;
+			xenbus_set_state(kids[i], XenbusStateInitialising);
 
 			/*
 			 * Find the new backend details and
@@ -783,16 +783,16 @@ xenbusb_resume(device_t dev)
 			if (error)
 				return (error);
 
-			DEVICE_RESUME(kids[i]);
-
 			statepath = malloc(ivars->xd_otherend_path_len
 			    + strlen("/state") + 1, M_XENBUS, M_WAITOK);
 			sprintf(statepath, "%s/state", ivars->xd_otherend_path);
 
 			free(ivars->xd_otherend_watch.node, M_XENBUS);
 			ivars->xd_otherend_watch.node = statepath;
-			xs_register_watch(&ivars->xd_otherend_watch);
 
+			DEVICE_RESUME(kids[i]);
+
+			xs_register_watch(&ivars->xd_otherend_watch);
 #if 0
 			/*
 			 * Can't do this yet since we are running in
diff --git a/sys/xen/xenbus/xenbusb_back.c b/sys/xen/xenbus/xenbusb_back.c
index 1252abe..351140a 100644
--- a/sys/xen/xenbus/xenbusb_back.c
+++ b/sys/xen/xenbus/xenbusb_back.c
@@ -292,7 +292,7 @@ static device_method_t xenbusb_back_methods[] = {
 	DEVMETHOD(device_detach,        bus_generic_detach), 
 	DEVMETHOD(device_shutdown,      bus_generic_shutdown), 
 	DEVMETHOD(device_suspend,       bus_generic_suspend), 
-	DEVMETHOD(device_resume,        bus_generic_resume), 
+	DEVMETHOD(device_resume,        xenbusb_resume), 
  
 	/* Bus Interface */ 
 	DEVMETHOD(bus_print_child,      xenbusb_print_child),
diff --git a/sys/xen/xenbus/xenbusb_front.c b/sys/xen/xenbus/xenbusb_front.c
index b4e470e..818e7f0 100644
--- a/sys/xen/xenbus/xenbusb_front.c
+++ b/sys/xen/xenbus/xenbusb_front.c
@@ -171,7 +171,7 @@ static device_method_t xenbusb_front_methods[] = {
 	DEVMETHOD(device_detach,        bus_generic_detach), 
 	DEVMETHOD(device_shutdown,      bus_generic_shutdown), 
 	DEVMETHOD(device_suspend,       bus_generic_suspend), 
-	DEVMETHOD(device_resume,        bus_generic_resume), 
+	DEVMETHOD(device_resume,        xenbusb_resume), 
  
 	/* Bus Interface */ 
 	DEVMETHOD(bus_print_child,      xenbusb_print_child),
diff --git a/sys/xen/xenstore/xenstore.c b/sys/xen/xenstore/xenstore.c
index ee1bb22..658e6e3 100644
--- a/sys/xen/xenstore/xenstore.c
+++ b/sys/xen/xenstore/xenstore.c
@@ -721,8 +721,8 @@ xs_reply_filter(uint32_t request_msg_type,
 	/*
 	 * The count of transactions drops if we attempted
 	 * to end a transaction (even if that attempt fails
-	 * in error), we receive a transaction end acknowledgement
-	 * or if our attempt to begin a transactionfails.
+	 * in error), we receive a transaction end acknowledgement,
+	 * or if our attempt to begin a transaction fails.
 	 */
 	if (request_msg_type == XS_TRANSACTION_END
 	 || (request_reply_error == 0 && reply_msg_type == XS_TRANSACTION_END)
@@ -1194,8 +1194,14 @@ xs_attach(device_t dev)
  * all transactions and individual requests have completed.
  */
 static int
-xs_suspend(device_t dev __unused)
+xs_suspend(device_t dev)
 {
+	int error;
+
+	/* Suspend child Xen devices. */
+	error = bus_generic_suspend(dev);
+	if (error != 0)
+		return (error);
 
 	sx_xlock(&xs.suspend_mutex);
 	sx_xlock(&xs.request_mutex);
@@ -1227,6 +1233,9 @@ xs_resume(device_t dev __unused)
 
 	sx_xunlock(&xs.suspend_mutex);
 
+	/* Resume child Xen devices. */
+	bus_generic_resume(dev);
+
 	return (0);
 }