Kieran Mansley
2007-Oct-03 13:18 UTC
[Xen-devel] [PATCH 4/6] Network acceleration improvements
Signed-off-by: Kieran Mansley <kmansley@solarflare.com>
Add version number to API between netfront and accel plugin
diff -r 4d2b719d5a57 drivers/xen/netfront/accel.c
--- a/drivers/xen/netfront/accel.c Wed Oct 03 13:36:28 2007 +0100
+++ b/drivers/xen/netfront/accel.c Wed Oct 03 13:36:34 2007 +0100
@@ -406,11 +406,26 @@ accelerator_probe_vifs_on_load(struct ne
/*
* Called by the netfront accelerator plugin module when it has loaded
*/
-int netfront_accelerator_loaded(const char *frontend,
+int netfront_accelerator_loaded(int version, const char *frontend,
struct netfront_accel_hooks *hooks)
{
struct netfront_accelerator *accelerator;
unsigned flags;
+
+ if (version != NETFRONT_ACCEL_VERSION) {
+ if (version > NETFRONT_ACCEL_VERSION) {
+ /* Caller has higher version number, leave it
+ up to them to decide whether to continue.
+ They can re-call with a lower number if
+ they''re happy to be compatible with us */
+ return NETFRONT_ACCEL_VERSION;
+ } else {
+ /* We have a more recent version than caller.
+ Currently reject, but may in future be able
+ to be backwardly compatible */
+ return -EPROTO;
+ }
+ }
spin_lock_irqsave(&accelerators_lock, flags);
diff -r 4d2b719d5a57 drivers/xen/netfront/netfront.h
--- a/drivers/xen/netfront/netfront.h Wed Oct 03 13:36:28 2007 +0100
+++ b/drivers/xen/netfront/netfront.h Wed Oct 03 13:37:13 2007 +0100
@@ -98,6 +98,11 @@ struct netfront_accel_hooks {
int (*check_busy)(struct net_device *dev);
};
+
+/* Version of API/protocol for communication between netfront and
+ acceleration plugin supported */
+#define NETFRONT_ACCEL_VERSION 0x00010000
+
/*
* Per-netfront device state for the accelerator. This is used to
* allow efficient per-netfront device access to the accelerator
@@ -221,8 +226,12 @@ struct netfront_info {
*
* frontend: the string describing the accelerator, currently the module name
* hooks: the hooks for netfront to use to call into the accelerator
- */
-extern int netfront_accelerator_loaded(const char *frontend,
+ * version: the version of API between frontend and plugin requested
+ *
+ * return: 0 on success, <0 on error, >0 (with version supported) on
+ * version mismatch
+ */
+extern int netfront_accelerator_loaded(int version, const char *frontend,
struct netfront_accel_hooks *hooks);
/*
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