xen-netback: add reference from xenvif to backend_info to facilitate coredump analysis

During coredump analysis, it is not easy to obtain the address of
backend_info in xen-netback.

So far there are two ways to obtain backend_info:

1. Do what xenbus_device_find() does for vmcore to find the xenbus_device
and then derive it from dev_get_drvdata().

2. Extract backend_info from callstack of xenwatch (e.g., netback_remove()
or frontend_changed()).

This patch adds a reference from xenvif to backend_info so that it would be
much more easier to obtain backend_info during coredump analysis.

Signed-off-by: Dongli Zhang <dongli.zhang@oracle.com>
Acked-by: Wei Liu <wei.liu2@citrix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 18 insertions, 0 deletions

diff --git a/drivers/net/xen-netback/common.h b/drivers/net/xen-netback/common.h
index 936c0b3e0ba2..05847eb91a1b 100644
--- a/drivers/net/xen-netback/common.h
+++ b/drivers/net/xen-netback/common.h
@@ -248,6 +248,22 @@ struct xenvif_hash {
 	struct xenvif_hash_cache cache;
 };
 
+struct backend_info {
+	struct xenbus_device *dev;
+	struct xenvif *vif;
+
+	/* This is the state that will be reflected in xenstore when any
+	 * active hotplug script completes.
+	 */
+	enum xenbus_state state;
+
+	enum xenbus_state frontend_state;
+	struct xenbus_watch hotplug_status_watch;
+	u8 have_hotplug_status_watch:1;
+
+	const char *hotplug_script;
+};
+
 struct xenvif {
 	/* Unique identifier for this interface. */
 	domid_t          domid;
@@ -283,6 +299,8 @@ struct xenvif {
 	struct xenbus_watch credit_watch;
 	struct xenbus_watch mcast_ctrl_watch;
 
+	struct backend_info *be;
+
 	spinlock_t lock;
 
 #ifdef CONFIG_DEBUG_FS