Backend net driver acceleration
Signed-off-by: Kieran Mansley <kmansley@xxxxxxxxxxxxxx>
diff -r fd61ea65cba3 drivers/xen/netback/common.h
--- a/drivers/xen/netback/common.h Thu Jun 14 14:51:20 2007 +0100
+++ b/drivers/xen/netback/common.h Thu Jun 14 14:56:41 2007 +0100
@@ -122,6 +122,41 @@ enum {
extern int netbk_copy_skb_mode;
+
+#include <xen/xenbus.h>
+
+/* Function pointers into netback accelerator plugin modules */
+struct netback_accel_hooks {
+ int (*probe)(struct xenbus_device *dev);
+ int (*remove)(struct xenbus_device *dev);
+};
+
+/* Structure to track the state of a netback accelerator plugin */
+struct netback_accelerator {
+ struct list_head link;
+ int id;
+ char *frontend;
+ struct netback_accel_hooks *hooks;
+};
+
+/* Connect an accelerator plugin module to netback */
+extern void netback_connect_accelerator(int id, const char *frontend,
+ struct netback_accel_hooks *hooks);
+/* Disconnect a previously connected accelerator pluging module */
+extern void netback_disconnect_accelerator(int id, const char *frontend);
+
+struct backend_info {
+ struct xenbus_device *dev;
+ netif_t *netif;
+ enum xenbus_state frontend_state;
+
+ /* State relating to the netback accelerator */
+ void *netback_accel_priv;
+ /* The accelerator that this backend is currently using */
+ struct netback_accelerator *accelerator;
+};
+
+
#define NET_TX_RING_SIZE __RING_SIZE((netif_tx_sring_t *)0, PAGE_SIZE)
#define NET_RX_RING_SIZE __RING_SIZE((netif_rx_sring_t *)0, PAGE_SIZE)
diff -r fd61ea65cba3 drivers/xen/netback/xenbus.c
--- a/drivers/xen/netback/xenbus.c Thu Jun 14 14:51:20 2007 +0100
+++ b/drivers/xen/netback/xenbus.c Thu Jun 14 14:56:41 2007 +0100
@@ -1,6 +1,7 @@
/* Xenbus code for netif backend
Copyright (C) 2005 Rusty Russell <rusty@xxxxxxxxxxxxxxx>
Copyright (C) 2005 XenSource Ltd
+ Copyright (c) 2007 Solarflare Communications, Inc.
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
@@ -28,11 +29,126 @@
printk("netback/xenbus (%s:%d) " fmt ".\n", __FUNCTION__, __LINE__, ##args)
#endif
-struct backend_info {
- struct xenbus_device *dev;
- netif_t *netif;
- enum xenbus_state frontend_state;
-};
+/*
+ * A list of available netback accelerator plugin modules (each list
+ * entry is of type struct netback_accelerator)
+ */
+static struct list_head accelerators_list;
+/* Lock used to protect access to accelerators_list */
+static spinlock_t accelerators_lock;
+
+/*
+ * Compare a backend to an accelerator, and decide if they are
+ * compatible (i.e. if the accelerator should be used by the
+ * backend)
+ */
+static int match_accelerator(struct backend_info *be,
+ struct netback_accelerator *accelerator)
+{
+ /*
+ * This could do with being more sophisticated. For example,
+ * determine which hardware is being used by each backend from
+ * the bridge and network topology of the domain
+ */
+ if ( be->accelerator == NULL )
+ return 1;
+ else
+ return 0;
+}
+
+/*
+ * Notify all suitable backends that a new accelerator is available
+ * and connected. This will also notify the accelerator plugin module
+ * that it is being used for a device through the probe hook.
+ */
+static int netback_accelerator_tell_backend(struct device *dev, void *arg)
+{
+ struct netback_accelerator *accelerator =
+ (struct netback_accelerator *)arg;
+ struct xenbus_device *xendev = to_xenbus_device(dev);
+
+ if( !strcmp("vif", xendev->devicetype) ) {
+ struct backend_info *be = xendev->dev.driver_data;
+
+ if ( match_accelerator(be, accelerator) ) {
+ be->accelerator = accelerator;
+ be->accelerator->hooks->probe(xendev);
+ }
+ }
+ return 0;
+}
+
+
+/*
+ * Entry point for an netback accelerator plugin module. Called to
+ * advertise its presence, and connect to any suitable backends.
+ */
+void netback_connect_accelerator(int id, const char *frontend,
+ struct netback_accel_hooks *hooks)
+{
+ struct netback_accelerator *new_accelerator =
+ kmalloc(sizeof(struct netback_accelerator), GFP_KERNEL);
+ unsigned frontend_len, flags;
+
+ if ( new_accelerator ) {
+ new_accelerator->id = id;
+
+ frontend_len = strlen(frontend)+1;
+ new_accelerator->frontend = kmalloc(frontend_len, GFP_KERNEL);
+ if ( !new_accelerator->frontend ) {
+ DPRINTK("%s: failed to allocate memory for frontend
string\n",
+ __FUNCTION__);
+ kfree(new_accelerator);
+ return;
+ }
+ strlcpy(new_accelerator->frontend, frontend, frontend_len);
+
+ new_accelerator->hooks = hooks;
+
+ spin_lock_irqsave(&accelerators_lock, flags);
+ list_add(&new_accelerator->link, &accelerators_list);
+ spin_unlock_irqrestore(&accelerators_lock, flags);
+
+ /* tell existing backends about new plugin */
+ xenbus_for_each_backend(new_accelerator,
+ netback_accelerator_tell_backend);
+ } else {
+ DPRINTK("%s: failed to allocate memory for accelerator\n",
+ __FUNCTION__);
+ return;
+ }
+}
+EXPORT_SYMBOL_GPL(netback_connect_accelerator);
+
+
+/*
+ * Disconnect an accelerator plugin module that has previously been
+ * connected.
+ *
+ * This should only be allowed when there are no remaining users -
+ * i.e. it is not necessary to go through and clear all the hooks, as
+ * they should have already been removed. However, this isn't
+ * currently enforced.
+ */
+void netback_disconnect_accelerator(int id, const char *frontend)
+{
+ struct netback_accelerator *accelerator, *next;
+ unsigned flags;
+
+ spin_lock_irqsave(&accelerators_lock, flags);
+ list_for_each_entry_safe(accelerator, next, &accelerators_list, link) {
+ if ( strcmp(frontend, accelerator->frontend) ) {
+ list_del(&accelerator->link);
+ spin_unlock_irqrestore(&accelerators_lock, flags);
+ kfree(accelerator->frontend);
+ kfree(accelerator);
+ return;
+ }
+ }
+ spin_unlock_irqrestore(&accelerators_lock, flags);
+}
+EXPORT_SYMBOL_GPL(netback_disconnect_accelerator);
+
static int connect_rings(struct backend_info *);
static void connect(struct backend_info *);
@@ -42,6 +158,11 @@ static int netback_remove(struct xenbus_
{
struct backend_info *be = dev->dev.driver_data;
+ /* Notify the accelerator (if any) of this device's removal */
+ if ( be->accelerator )
+ be->accelerator->hooks->remove(dev);
+ be->accelerator = NULL;
+
if (be->netif) {
netif_disconnect(be->netif);
be->netif = NULL;
@@ -61,6 +182,8 @@ static int netback_probe(struct xenbus_d
{
const char *message;
struct xenbus_transaction xbt;
+ struct netback_accelerator *accelerator;
+ unsigned flags;
int err;
int sg;
struct backend_info *be = kzalloc(sizeof(struct backend_info),
@@ -124,6 +247,20 @@ static int netback_probe(struct xenbus_d
xenbus_dev_fatal(dev, err, "completing transaction");
goto fail;
}
+
+ /*
+ * Check list of accelerators to see if any is suitable, and
+ * use it if it is.
+ */
+ spin_lock_irqsave(&accelerators_lock, flags);
+ list_for_each_entry( accelerator, &accelerators_list, link ) {
+ if ( match_accelerator(be, accelerator) ) {
+ be->accelerator = accelerator;
+ be->accelerator->hooks->probe(dev);
+ break;
+ }
+ }
+ spin_unlock_irqrestore(&accelerators_lock, flags);
err = xenbus_switch_state(dev, XenbusStateInitWait);
if (err)
@@ -449,5 +586,8 @@ static struct xenbus_driver netback = {
void netif_xenbus_init(void)
{
+ INIT_LIST_HEAD(&accelerators_list);
+ spin_lock_init(&accelerators_lock);
+
xenbus_register_backend(&netback);
}
backend_accel
Description: Text document
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