Frontend net driver acceleration
diff -r cd3ade350f3f drivers/xen/netfront/netfront.c
--- a/drivers/xen/netfront/netfront.c Thu Jun 14 15:04:32 2007 +0100
+++ b/drivers/xen/netfront/netfront.c Fri Jun 15 09:34:41 2007 +0100
@@ -3,6 +3,7 @@
*
* Copyright (c) 2002-2005, K A Fraser
* 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 version 2
@@ -47,6 +48,7 @@
#include <linux/if_ether.h>
#include <linux/io.h>
#include <linux/moduleparam.h>
+#include <linux/list.h>
#include <net/sock.h>
#include <net/pkt_sched.h>
#include <net/arp.h>
@@ -73,6 +75,8 @@ struct netfront_cb {
};
#define NETFRONT_SKB_CB(skb) ((struct netfront_cb *)((skb)->cb))
+
+#include "netfront.h"
/*
* Mutually-exclusive module options to select receive data path:
@@ -144,57 +148,6 @@ static inline int netif_needs_gso(struct
#define GRANT_INVALID_REF 0
-#define NET_TX_RING_SIZE __RING_SIZE((struct netif_tx_sring *)0, PAGE_SIZE)
-#define NET_RX_RING_SIZE __RING_SIZE((struct netif_rx_sring *)0, PAGE_SIZE)
-
-struct netfront_info {
- struct list_head list;
- struct net_device *netdev;
-
- struct net_device_stats stats;
-
- struct netif_tx_front_ring tx;
- struct netif_rx_front_ring rx;
-
- spinlock_t tx_lock;
- spinlock_t rx_lock;
-
- unsigned int irq;
- unsigned int copying_receiver;
- unsigned int carrier;
-
- /* Receive-ring batched refills. */
-#define RX_MIN_TARGET 8
-#define RX_DFL_MIN_TARGET 64
-#define RX_MAX_TARGET min_t(int, NET_RX_RING_SIZE, 256)
- unsigned rx_min_target, rx_max_target, rx_target;
- struct sk_buff_head rx_batch;
-
- struct timer_list rx_refill_timer;
-
- /*
- * {tx,rx}_skbs store outstanding skbuffs. The first entry in tx_skbs
- * is an index into a chain of free entries.
- */
- struct sk_buff *tx_skbs[NET_TX_RING_SIZE+1];
- struct sk_buff *rx_skbs[NET_RX_RING_SIZE];
-
-#define TX_MAX_TARGET min_t(int, NET_RX_RING_SIZE, 256)
- grant_ref_t gref_tx_head;
- grant_ref_t grant_tx_ref[NET_TX_RING_SIZE + 1];
- grant_ref_t gref_rx_head;
- grant_ref_t grant_rx_ref[NET_RX_RING_SIZE];
-
- struct xenbus_device *xbdev;
- int tx_ring_ref;
- int rx_ring_ref;
- u8 mac[ETH_ALEN];
-
- unsigned long rx_pfn_array[NET_RX_RING_SIZE];
- struct multicall_entry rx_mcl[NET_RX_RING_SIZE+1];
- struct mmu_update rx_mmu[NET_RX_RING_SIZE];
-};
-
struct netfront_rx_info {
struct netif_rx_response rx;
struct netif_extra_info extras[XEN_NETIF_EXTRA_TYPE_MAX - 1];
@@ -278,6 +231,369 @@ static void xennet_sysfs_delif(struct ne
#define xennet_sysfs_delif(dev) do { } while(0)
#endif
+/*
+ * List of all netfront accelerator plugin modules available. Each
+ * list entry is of type struct netfront_accelerator.
+ */
+static struct list_head accelerators_list;
+/*
+ * Lock to protect access to accelerators_list, and also used to
+ * protect the hooks_usecount field in struct netfront_accelerator
+ * against concurrent access
+ */
+static spinlock_t accelerators_lock;
+
+/*
+ * Safely remove the accelerator function hooks from a netfront state.
+ * Must only be called when there are no current users of the hooks.
+ */
+static void accelerator_remove_hooks(struct netfront_accelerator *accelerator)
+{
+ struct netfront_accel_vif_state *vif_state;
+
+ list_for_each_entry( vif_state,
+ &accelerator->vif_states,
+ link ) {
+ /* Make sure there are no data path operations going on */
+ netif_poll_disable(vif_state->np->netdev);
+ netif_tx_lock_bh(vif_state->np->netdev);
+
+ /*
+ * Remove the hooks, but leave the vif_state on the
+ * accelerator's list as that signifies this vif is
+ * interested in using that accelerator if it becomes
+ * available again
+ */
+ vif_state->hooks = NULL;
+
+ netif_tx_unlock_bh(vif_state->np->netdev);
+ netif_poll_enable(vif_state->np->netdev);
+ }
+
+ accelerator->hooks = NULL;
+
+ /* Signal that all users of hooks are done */
+ up(&accelerator->exit_semaphore);
+}
+
+
+/*
+ * Compare a frontend description string against an accelerator to see
+ * if they match. Would ultimately be nice to replace the string with
+ * a unique numeric identifier for each accelerator.
+ */
+static int match_accelerator(const char *frontend,
+ struct netfront_accelerator *accelerator)
+{
+ return strcmp(frontend, accelerator->frontend) == 0;
+}
+
+
+/*
+ * Add a frontend vif to the list of vifs that is using a netfront
+ * accelerator plugin module.
+ */
+static void add_accelerator_vif(struct netfront_accelerator *accelerator,
+ struct netfront_info *np,
+ struct xenbus_device *dev)
+{
+ np->accelerator = accelerator;
+ np->accel_vif_state.np = np;
+ np->accel_vif_state.dev = dev;
+
+ list_add(&np->accel_vif_state.link, &accelerator->vif_states);
+}
+
+/*
+ * Initialise the netfront state of an accelerator plugin module.
+ */
+static int init_accelerator(const char *frontend,
+ struct netfront_accelerator **result)
+{
+ struct netfront_accelerator *accelerator =
+ kmalloc(sizeof(struct netfront_accelerator), GFP_KERNEL);
+ int frontend_len;
+
+ if ( !accelerator ) {
+ DPRINTK("%s: no memory for accelerator", __FUNCTION__);
+ return -ENOMEM;
+ }
+
+ frontend_len = strlen(frontend) + 1;
+ accelerator->frontend = kmalloc(frontend_len, GFP_KERNEL);
+ if ( !accelerator->frontend ) {
+ DPRINTK("%s: no memory for accelerator", __FUNCTION__);
+ kfree(accelerator);
+ return -ENOMEM;
+ }
+ strlcpy(accelerator->frontend, frontend, frontend_len);
+
+ INIT_LIST_HEAD(&accelerator->vif_states);
+
+ accelerator->hooks = NULL;
+ accelerator->hooks_usecount = 0;
+
+ list_add(&accelerator->link, &accelerators_list);
+
+ *result = accelerator;
+
+ return 0;
+}
+
+/*
+ * Modify the hooks stored in the per-vif state to match that in the
+ * netfront accelerator's state.
+ */
+static void
+accelerator_set_vif_state_hooks(struct netfront_accel_vif_state *vif_state)
+{
+ /* Make sure there are no data path operations going on */
+ netif_poll_disable(vif_state->np->netdev);
+ netif_tx_lock_bh(vif_state->np->netdev);
+
+ vif_state->hooks = vif_state->np->accelerator->hooks;
+
+ netif_tx_unlock_bh(vif_state->np->netdev);
+ netif_poll_enable(vif_state->np->netdev);
+}
+
+
+/*
+ * Request that a particular netfront accelerator plugin is loaded.
+ * Usually called as a result of the vif configuration specifying
+ * which one to use.
+ */
+static int netfront_load_accelerator(struct netfront_info *np,
+ struct xenbus_device *dev,
+ const char *frontend)
+{
+ struct netfront_accelerator *accelerator;
+ int rc;
+ unsigned flags;
+
+ spin_lock_irqsave(&accelerators_lock, flags);
+
+ /*
+ * Look at list of loaded accelerators to see if the requested
+ * one is already there
+ */
+ list_for_each_entry( accelerator, &accelerators_list, link ) {
+ if ( match_accelerator(frontend, accelerator) ) {
+ /*
+ * Include this frontend device on the
+ * accelerator's list
+ */
+ add_accelerator_vif(accelerator, np, dev);
+
+ ++accelerator->hooks_usecount;
+
+ if ( accelerator->hooks == NULL )
+ DPRINTK("%s: no hooks set", __FUNCTION__);
+ else {
+ spin_unlock_irqrestore(&accelerators_lock,
flags);
+ accelerator->hooks->new_device(np->netdev,
dev);
+ spin_lock_irqsave(&accelerators_lock, flags);
+ }
+
+ if ( (--accelerator->hooks_usecount) == 0 )
+ accelerator_remove_hooks(accelerator);
+ spin_unlock_irqrestore(&accelerators_lock, flags);
+
+ /*
+ * Hooks will get linked into vif_state by a
+ * future call by the accelerator to
+ * netfront_accelerator_ready()
+ */
+
+ return 0;
+ }
+ }
+
+ /* Couldn't find it, so create a new one and load the module */
+ if ( ( rc = init_accelerator(frontend, &accelerator) ) < 0 ) {
+ spin_unlock_irqrestore(&accelerators_lock, flags);
+ return rc;
+ }
+
+ /* Include this frontend device on the accelerator's list */
+ add_accelerator_vif(accelerator, np, dev);
+
+ spin_unlock_irqrestore(&accelerators_lock, flags);
+
+ DPRINTK("%s: loading module %s\n", __FUNCTION__, frontend);
+
+ /* load module */
+ request_module("%s", frontend);
+
+ /*
+ * Module should now call netfront_accelerator_loaded() once
+ * it's up and running, and we can continue from there
+ */
+
+ return 0;
+}
+
+/*
+ * Go through all the netfront vifs and see if they have requested
+ * this accelerator. Notify the accelerator plugin of the relevant
+ * device if so. Called when an accelerator plugin module is first
+ * loaded and connects to netfront.
+ */
+static void
+accelerator_probe_vifs_on_load(struct netfront_accelerator *accelerator)
+{
+ struct netfront_accel_vif_state *accel_vif_state;
+
+ DPRINTK("%s: %p\n", __FUNCTION__, accelerator);
+
+ list_for_each_entry( accel_vif_state,
+ &accelerator->vif_states, link ) {
+ struct netfront_info *np = accel_vif_state->np;
+
+ accelerator->hooks->new_device(np->netdev,
+ accel_vif_state->dev);
+
+ /*
+ * Hooks will get linked into vif_state by a call to
+ * netfront_accelerator_ready() once accelerator
+ * plugin is ready for action
+ */
+ }
+}
+
+
+/*
+ * Called by the netfront accelerator plugin module when it has loaded
+ */
+int netfront_accelerator_loaded(const char *frontend,
+ struct netfront_accel_hooks *hooks)
+{
+ struct netfront_accelerator *accelerator;
+ unsigned flags;
+
+ spin_lock_irqsave(&accelerators_lock, flags);
+
+ /* Look through list of accelerators to see if it has already
+ been requested */
+ list_for_each_entry( accelerator, &accelerators_list, link ) {
+ if ( match_accelerator(frontend, accelerator) ) {
+ /*
+ * Deliberate double inc of usecount here -
+ * one to initialise it to 1 now hooks is
+ * being set (which persists until unloaded),
+ * and one for the use of hooks in this
+ * function (we don't want an unload to
+ * succeed in clearing hooks in the middle)
+ */
+ BUG_ON(accelerator->hooks != NULL ||
+ accelerator->hooks_usecount != 0);
+ accelerator->hooks_usecount = 2;
+
+ accelerator->hooks = hooks;
+
+ spin_unlock_irqrestore(&accelerators_lock, flags);
+
+ accelerator_probe_vifs_on_load(accelerator);
+
+ spin_lock_irqsave(&accelerators_lock, flags);
+ if ( (--accelerator->hooks_usecount) == 0 )
+ accelerator_remove_hooks(accelerator);
+ spin_unlock_irqrestore(&accelerators_lock, flags);
+
+ return 0;
+ }
+ }
+
+ /* If it wasn't in the list, add it now so that when it is
+ requested the caller will find it */
+ DPRINTK("%s: Couldn't find matching accelerator (%s)\n",
+ __FUNCTION__, frontend);
+
+ init_accelerator(frontend, &accelerator);
+
+ spin_unlock_irqrestore(&accelerators_lock, flags);
+
+ return 0;
+}
+EXPORT_SYMBOL_GPL(netfront_accelerator_loaded);
+
+
+/*
+ * Called by the accelerator module after it has been probed with a
+ * network device to say that it is ready to start accelerating
+ * traffic on that device
+ */
+void netfront_accelerator_ready(const char *frontend,
+ struct xenbus_device *dev)
+{
+ struct netfront_accelerator *accelerator;
+ struct netfront_accel_vif_state *accel_vif_state;
+ unsigned flags;
+
+ spin_lock_irqsave(&accelerators_lock, flags);
+
+ list_for_each_entry( accelerator, &accelerators_list, link ) {
+ if ( match_accelerator(frontend, accelerator) ) {
+ ++accelerator->hooks_usecount;
+ spin_unlock_irqrestore(&accelerators_lock, flags);
+
+ list_for_each_entry( accel_vif_state,
+ &accelerator->vif_states, link ) {
+ if ( accel_vif_state->dev == dev )
+ accelerator_set_vif_state_hooks
+ (accel_vif_state);
+ }
+
+ spin_lock_irqsave(&accelerators_lock, flags);
+ if ( (--accelerator->hooks_usecount) == 0 )
+ accelerator_remove_hooks(accelerator);
+ spin_unlock_irqrestore(&accelerators_lock, flags);
+
+ return;
+ }
+ }
+
+ spin_unlock_irqrestore(&accelerators_lock, flags);
+}
+EXPORT_SYMBOL_GPL(netfront_accelerator_ready);
+
+
+/*
+ * Called by a netfront accelerator when it is unloaded. This safely
+ * removes the hooks into the plugin and blocks until all devices have
+ * finished using it, so on return it is safe to unload.
+ */
+void netfront_accelerator_unloaded(const char *frontend)
+{
+ struct netfront_accelerator *accelerator;
+ unsigned flags;
+
+ spin_lock_irqsave(&accelerators_lock, flags);
+
+ list_for_each_entry( accelerator, &accelerators_list, link ) {
+ if ( match_accelerator(frontend, accelerator) ) {
+ /*
+ * Use semaphore to ensure we know when all
+ * uses of hooks are complete
+ */
+ sema_init(&accelerator->exit_semaphore, 0);
+
+ if ( (--accelerator->hooks_usecount) == 0 )
+ accelerator_remove_hooks(accelerator);
+
+ spin_unlock_irqrestore(&accelerators_lock, flags);
+
+ /* Wait for hooks to be unused, then return */
+ down(&accelerator->exit_semaphore);
+
+ return;
+ }
+ }
+ spin_unlock_irqrestore(&accelerators_lock, flags);
+}
+EXPORT_SYMBOL_GPL(netfront_accelerator_unloaded);
+
+
static inline int xennet_can_sg(struct net_device *dev)
{
return dev->features & NETIF_F_SG;
@@ -331,8 +647,29 @@ static int __devexit netfront_remove(str
static int __devexit netfront_remove(struct xenbus_device *dev)
{
struct netfront_info *info = dev->dev.driver_data;
+ unsigned flags;
DPRINTK("%s\n", dev->nodename);
+
+ /*
+ * Call the remove accelerator hook. The use count for the
+ * accelerator's hooks is incremented for the duration of the
+ * call to prevent the accelerator being able to modify the
+ * hooks in the middle (by, for example, unloading)
+ */
+ if ( info->accel_vif_state.hooks ) {
+ spin_lock_irqsave(&accelerators_lock, flags);
+ ++info->accelerator->hooks_usecount;
+ spin_unlock_irqrestore(&accelerators_lock, flags);
+
+ if ( info->accel_vif_state.hooks )
+ info->accel_vif_state.hooks->remove(dev);
+
+ spin_lock_irqsave(&accelerators_lock, flags);
+ if ( (--info->accelerator->hooks_usecount) == 0 )
+ accelerator_remove_hooks(info->accelerator);
+ spin_unlock_irqrestore(&accelerators_lock, flags);
+ }
netif_disconnect_backend(info);
@@ -356,8 +693,29 @@ static int netfront_resume(struct xenbus
static int netfront_resume(struct xenbus_device *dev)
{
struct netfront_info *info = dev->dev.driver_data;
+ unsigned flags;
DPRINTK("%s\n", dev->nodename);
+
+ /*
+ * Call the resume accelerator hook. The use count for the
+ * accelerator's hooks is incremented for the duration of
+ * the call to prevent the accelerator being able to modify
+ * the * hooks in the middle (by, for example, unloading)
+ */
+ if ( info->accel_vif_state.hooks ) {
+ spin_lock_irqsave(&accelerators_lock, flags);
+ ++info->accelerator->hooks_usecount;
+ spin_unlock_irqrestore(&accelerators_lock, flags);
+
+ if ( info->accel_vif_state.hooks )
+ info->accel_vif_state.hooks->resume(dev);
+
+ spin_lock_irqsave(&accelerators_lock, flags);
+ if ( (--info->accelerator->hooks_usecount) == 0 )
+ accelerator_remove_hooks(info->accelerator);
+ spin_unlock_irqrestore(&accelerators_lock, flags);
+ }
netif_disconnect_backend(info);
return 0;
@@ -553,6 +911,7 @@ static void backend_changed(struct xenbu
{
struct netfront_info *np = dev->dev.driver_data;
struct net_device *netdev = np->netdev;
+ unsigned flags;
DPRINTK("%s\n", xenbus_strstate(backend_state));
@@ -577,6 +936,27 @@ static void backend_changed(struct xenbu
xenbus_frontend_closed(dev);
break;
}
+
+ /*
+ * Call the backend_changed accelerator hook. The use count
+ * for the accelerator's hooks is incremented for the duration
+ * of the call to prevent the accelerator being able to modify
+ * the hooks in the middle (by, for example, unloading)
+ */
+ if ( np->accel_vif_state.hooks ) {
+ spin_lock_irqsave(&accelerators_lock, flags);
+ ++np->accelerator->hooks_usecount;
+ spin_unlock_irqrestore(&accelerators_lock, flags);
+
+ if ( np->accel_vif_state.hooks )
+ np->accel_vif_state.hooks->backend_changed
+ (dev, backend_state);
+
+ spin_lock_irqsave(&accelerators_lock, flags);
+ if ( (--np->accelerator->hooks_usecount) == 0 )
+ accelerator_remove_hooks(np->accelerator);
+ spin_unlock_irqrestore(&accelerators_lock, flags);
+ }
}
/** Send a packet on a net device to encourage switches to learn the
@@ -613,19 +993,65 @@ static inline int netfront_tx_slot_avail
(TX_MAX_TARGET - MAX_SKB_FRAGS - 2));
}
+
+static inline
+int netfront_check_accelerator_queue_busy(struct net_device *dev,
+ struct netfront_info *np)
+{
+ int rc = 1;
+ unsigned flags;
+
+ /*
+ * Call the check busy accelerator hook. The use count for the
+ * accelerator's hooks is incremented for the duration of the
+ * call to prevent the accelerator being able to modify the
+ * hooks in the middle (by, for example, unloading)
+ */
+ if ( np->accel_vif_state.hooks ) {
+ spin_lock_irqsave(&accelerators_lock, flags);
+ ++(np->accelerator->hooks_usecount);
+ spin_unlock_irqrestore(&accelerators_lock, flags);
+
+ if ( np->accel_vif_state.hooks )
+ rc = np->accel_vif_state.hooks->check_busy(dev);
+
+ spin_lock_irqsave(&accelerators_lock, flags);
+ if ( (--(np->accelerator->hooks_usecount) == 0 ) )
+ accelerator_remove_hooks(np->accelerator);
+ spin_unlock_irqrestore(&accelerators_lock, flags);
+ }
+
+ return rc;
+}
+
+
static inline void network_maybe_wake_tx(struct net_device *dev)
{
struct netfront_info *np = netdev_priv(dev);
if (unlikely(netif_queue_stopped(dev)) &&
netfront_tx_slot_available(np) &&
- likely(netif_running(dev)))
+ likely(netif_running(dev)) &&
+ netfront_check_accelerator_queue_busy(dev, np))
netif_wake_queue(dev);
}
+
+int netfront_check_queue_busy(struct net_device *dev)
+{
+ struct netfront_info *np = netdev_priv(dev);
+
+ return unlikely(netif_queue_stopped(dev)) &&
+ netfront_tx_slot_available(np) &&
+ likely(netif_running(dev));
+}
+EXPORT_SYMBOL(netfront_check_queue_busy);
+
+
static int network_open(struct net_device *dev)
{
struct netfront_info *np = netdev_priv(dev);
+ unsigned flags;
memset(&np->stats, 0, sizeof(np->stats));
@@ -633,8 +1059,34 @@ static int network_open(struct net_devic
if (netfront_carrier_ok(np)) {
network_alloc_rx_buffers(dev);
np->rx.sring->rsp_event = np->rx.rsp_cons + 1;
- if (RING_HAS_UNCONSUMED_RESPONSES(&np->rx))
+ if (RING_HAS_UNCONSUMED_RESPONSES(&np->rx)){
+ /*
+ * Call the stop_napi_interrupts accelerator
+ * hook. The use count for the accelerator's
+ * hooks is incremented for the duration of
+ * the call to prevent the accelerator being
+ * able to modify the hooks in the middle (by,
+ * for example, unloading)
+ */
+ if ( np->accel_vif_state.hooks ) {
+ spin_lock_irqsave(&accelerators_lock, flags);
+ ++np->accelerator->hooks_usecount;
+ spin_unlock_irqrestore(&accelerators_lock,
+ flags);
+
+ if ( np->accel_vif_state.hooks )
+
np->accel_vif_state.hooks->stop_napi_interrupts(dev);
+
+ spin_lock_irqsave(&accelerators_lock, flags);
+ if ( (--np->accelerator->hooks_usecount)==0 )
+ accelerator_remove_hooks
+ (np->accelerator);
+ spin_unlock_irqrestore(&accelerators_lock,
+ flags);
+ }
+
netif_rx_schedule(dev);
+ }
}
spin_unlock_bh(&np->rx_lock);
@@ -702,6 +1154,30 @@ static void rx_refill_timeout(unsigned l
static void rx_refill_timeout(unsigned long data)
{
struct net_device *dev = (struct net_device *)data;
+ struct netfront_info *np = netdev_priv(dev);
+ unsigned flags;
+
+ /*
+ * Call the stop_napi_interrupts accelerator hook. The use
+ * count for the accelerator's hooks is incremented for the
+ * duration of the call to prevent the accelerator being able
+ * to modify the hooks in the middle (by, for example,
+ * unloading)
+ */
+ if ( np->accel_vif_state.hooks ) {
+ spin_lock_irqsave(&accelerators_lock, flags);
+ ++np->accelerator->hooks_usecount;
+ spin_unlock_irqrestore(&accelerators_lock, flags);
+
+ if ( np->accel_vif_state.hooks )
+ np->accel_vif_state.hooks->stop_napi_interrupts(dev);
+
+ spin_lock_irqsave(&accelerators_lock, flags);
+ if ( (--np->accelerator->hooks_usecount) == 0 )
+ accelerator_remove_hooks(np->accelerator);
+ spin_unlock_irqrestore(&accelerators_lock, flags);
+ }
+
netif_rx_schedule(dev);
}
@@ -941,6 +1417,12 @@ static int network_start_xmit(struct sk_
unsigned int offset = offset_in_page(data);
unsigned int len = skb_headlen(skb);
+ /* Check the fast path, if hooks are available */
+ if ( np->accel_vif_state.hooks &&
+ np->accel_vif_state.hooks->start_xmit(skb, dev) ) {
+ return 0;
+ }
+
frags += (offset + len + PAGE_SIZE - 1) / PAGE_SIZE;
if (unlikely(frags > MAX_SKB_FRAGS + 1)) {
printk(KERN_ALERT "xennet: skb rides the rocket: %d frags\n",
@@ -1037,15 +1519,41 @@ static irqreturn_t netif_int(int irq, vo
{
struct net_device *dev = dev_id;
struct netfront_info *np = netdev_priv(dev);
- unsigned long flags;
+ unsigned long flags, flags1;
spin_lock_irqsave(&np->tx_lock, flags);
if (likely(netfront_carrier_ok(np))) {
network_tx_buf_gc(dev);
/* Under tx_lock: protects access to rx shared-ring indexes. */
- if (RING_HAS_UNCONSUMED_RESPONSES(&np->rx))
+ if (RING_HAS_UNCONSUMED_RESPONSES(&np->rx)) {
+ /*
+ * Call the stop_napi_interrupts accelerator
+ * hook. The use count for the accelerator's
+ * hooks is incremented for the duration of
+ * the call to prevent the accelerator being
+ * able to modify the hooks in the middle (by,
+ * for example, unloading)
+ */
+ if ( np->accel_vif_state.hooks ) {
+ spin_lock_irqsave(&accelerators_lock, flags1);
+ ++np->accelerator->hooks_usecount;
+ spin_unlock_irqrestore(&accelerators_lock,
+ flags1);
+
+ if ( np->accel_vif_state.hooks )
+
np->accel_vif_state.hooks->stop_napi_interrupts(dev);
+
+ spin_lock_irqsave(&accelerators_lock, flags1);
+ if ( (--np->accelerator->hooks_usecount)==0 )
+ accelerator_remove_hooks
+ (np->accelerator);
+ spin_unlock_irqrestore(&accelerators_lock,
+ flags1);
+ }
+
netif_rx_schedule(dev);
+ }
}
spin_unlock_irqrestore(&np->tx_lock, flags);
@@ -1305,7 +1813,7 @@ static int netif_poll(struct net_device
struct netif_extra_info *extras = rinfo.extras;
RING_IDX i, rp;
struct multicall_entry *mcl;
- int work_done, budget, more_to_do = 1;
+ int work_done, budget, more_to_do = 1, accel_more_to_do = 1;
struct sk_buff_head rxq;
struct sk_buff_head errq;
struct sk_buff_head tmpq;
@@ -1472,6 +1980,20 @@ err:
network_alloc_rx_buffers(dev);
+ if (work_done < budget) {
+ /* there's some spare capacity, try the accelerated path */
+ int accel_budget = budget - work_done;
+ int accel_budget_start = accel_budget;
+
+ if ( np->accel_vif_state.hooks ) {
+ accel_more_to_do =
+ np->accel_vif_state.hooks->netdev_poll
+ (dev, &accel_budget);
+ work_done += (accel_budget_start - accel_budget);
+ } else
+ accel_more_to_do = 0;
+ }
+
*pbudget -= work_done;
dev->quota -= work_done;
@@ -1479,15 +2001,28 @@ err:
local_irq_save(flags);
RING_FINAL_CHECK_FOR_RESPONSES(&np->rx, more_to_do);
- if (!more_to_do)
+
+ if (!more_to_do && !accel_more_to_do) {
+ /*
+ * Slow path has nothing more to do, see if
+ * fast path is likewise
+ */
+ if ( np->accel_vif_state.hooks ) {
+ accel_more_to_do =
+
np->accel_vif_state.hooks->start_napi_interrupts(dev);
+ }
+ }
+
+ if (!more_to_do && !accel_more_to_do) {
__netif_rx_complete(dev);
+ }
local_irq_restore(flags);
}
spin_unlock(&np->rx_lock);
-
- return more_to_do;
+
+ return more_to_do | accel_more_to_do;
}
static void netif_release_tx_bufs(struct netfront_info *np)
@@ -1687,7 +2222,9 @@ static int network_connect(struct net_de
struct sk_buff *skb;
grant_ref_t ref;
netif_rx_request_t *req;
- unsigned int feature_rx_copy, feature_rx_flip;
+ unsigned int feature_rx_copy, feature_rx_flip, feature_accel;
+ char *accel_frontend;
+ int accel_len;
err = xenbus_scanf(XBT_NIL, np->xbdev->otherend,
"feature-rx-copy", "%u", &feature_rx_copy);
@@ -1698,6 +2235,13 @@ static int network_connect(struct net_de
if (err != 1)
feature_rx_flip = 1;
+ feature_accel = 1;
+ accel_frontend = xenbus_read(XBT_NIL, np->xbdev->otherend,
+ "accel", &accel_len);
+ if ( IS_ERR(accel_frontend) ) {
+ feature_accel = 0;
+ }
+
/*
* Copy packets on receive path if:
* (a) This was requested by user, and the backend supports it; or
@@ -1709,6 +2253,11 @@ static int network_connect(struct net_de
err = talk_to_backend(np->xbdev, np);
if (err)
return err;
+
+ if ( feature_accel ) {
+ netfront_load_accelerator(np, np->xbdev, accel_frontend);
+ kfree(accel_frontend);
+ }
xennet_set_features(dev);
@@ -1955,6 +2504,7 @@ static struct net_device * __devinit cre
spin_lock_init(&np->tx_lock);
spin_lock_init(&np->rx_lock);
+ np->accel_vif_state.hooks = NULL;
skb_queue_head_init(&np->rx_batch);
np->rx_target = RX_DFL_MIN_TARGET;
@@ -2110,6 +2660,9 @@ static int __init netif_init(void)
if (is_initial_xendomain())
return 0;
+ INIT_LIST_HEAD(&accelerators_list);
+ spin_lock_init(&accelerators_lock);
+
IPRINTK("Initialising virtual ethernet driver.\n");
(void)register_inetaddr_notifier(¬ifier_inetdev);
diff -r cd3ade350f3f drivers/xen/netfront/netfront.h
--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/drivers/xen/netfront/netfront.h Thu Jun 14 14:57:34 2007 +0100
@@ -0,0 +1,198 @@
+/******************************************************************************
+ * Virtual network driver for conversing with remote driver backends.
+ *
+ * Copyright (c) 2002-2005, K A Fraser
+ * 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 version 2
+ * as published by the Free Software Foundation; or, when distributed
+ * separately from the Linux kernel or incorporated into other
+ * software packages, subject to the following license:
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this source file (the "Software"), to deal in the Software without
+ * restriction, including without limitation the rights to use, copy, modify,
+ * merge, publish, distribute, sublicense, and/or sell copies of the Software,
+ * and to permit persons to whom the Software is furnished to do so, subject to
+ * the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
+ * IN THE SOFTWARE.
+ */
+
+#ifndef NETFRONT_H
+#define NETFRONT_H
+
+#include <xen/interface/io/netif.h>
+#include <linux/netdevice.h>
+#include <linux/skbuff.h>
+#include <linux/list.h>
+
+#define NET_TX_RING_SIZE __RING_SIZE((struct netif_tx_sring *)0, PAGE_SIZE)
+#define NET_RX_RING_SIZE __RING_SIZE((struct netif_rx_sring *)0, PAGE_SIZE)
+
+#include <xen/xenbus.h>
+/* Function pointer table for hooks into a network acceleration
+ plugin. These are called at appropriate points from the netfront
+ driver */
+struct netfront_accel_hooks {
+ /* new_device: The plugin is asked to support a new network interface
*/
+ int (*new_device)(struct net_device *net_dev, struct xenbus_device
*dev);
+ /* suspend, resume, remove: Equivalent to the normal xenbus_*
callbacks */
+ int (*suspend)(struct xenbus_device *dev);
+ int (*resume)(struct xenbus_device *dev);
+ int (*remove)(struct xenbus_device *dev);
+ /* backend_changed: Callback from watch based on backend's
+ xenbus state changing */
+ void (*backend_changed)(struct xenbus_device *dev,
+ enum xenbus_state backend_state);
+ /* The net_device is being polled, check the accelerated
+ hardware for any pending packets */
+ int (*netdev_poll)(struct net_device *dev, int *pbudget);
+ /* start_xmit: Used to give the accelerated plugin the option
+ of sending a packet. Returns non-zero if has done so, or
+ zero to decline and force the packet onto normal send path */
+ int (*start_xmit)(struct sk_buff *skb, struct net_device *dev);
+ /* start/stop_napi_interrupts Used by netfront to indicate
+ when napi interrupts should be enabled or disabled */
+ int (*start_napi_interrupts)(struct net_device *dev);
+ void (*stop_napi_interrupts)(struct net_device *dev);
+ /* Called before re-enabling the TX queue to check the fast
+ path has slots too */
+ int (*check_busy)(struct net_device *dev);
+};
+
+/* Per-netfront device state for the accelerator. This is used to
+ allow efficient per-netfront device access to the accelerator hooks */
+struct netfront_accel_vif_state {
+ struct list_head link;
+
+ struct xenbus_device *dev;
+ struct netfront_info *np;
+ struct netfront_accel_hooks *hooks;
+};
+
+/* Per-accelerator state stored in netfront. These form a list that
+ is used to track which devices are accelerated by which plugins,
+ and what plugins are available/have been requested */
+struct netfront_accelerator {
+ /* Used to make a list */
+ struct list_head link;
+ /* ID of the accelerator */
+ int id;
+ /* String describing the accelerator. Currently this is the
+ name of the accelerator module. This is provided by the
+ backend accelerator through xenstore */
+ char *frontend;
+ /* The hooks into the accelerator plugin module */
+ struct netfront_accel_hooks *hooks;
+ /* Protect against removal of hooks while in use, must hold
+ accelerators_lock to change */
+ unsigned hooks_usecount;
+ /* List of per-netfront device state (struct netfront_accel_vif_state)
+ for each netfront device that is using this accelerator */
+ struct list_head vif_states;
+ /* Semaphore to signal that all users of this accelerator have
+ finished using it before module is unloaded */
+ struct semaphore exit_semaphore;
+};
+
+
+struct netfront_info {
+ struct list_head list;
+ struct net_device *netdev;
+
+ struct net_device_stats stats;
+
+ struct netif_tx_front_ring tx;
+ struct netif_rx_front_ring rx;
+
+ spinlock_t tx_lock;
+ spinlock_t rx_lock;
+
+ unsigned int irq;
+ unsigned int copying_receiver;
+ unsigned int carrier;
+
+ /* Receive-ring batched refills. */
+#define RX_MIN_TARGET 8
+#define RX_DFL_MIN_TARGET 64
+#define RX_MAX_TARGET min_t(int, NET_RX_RING_SIZE, 256)
+ unsigned rx_min_target, rx_max_target, rx_target;
+ struct sk_buff_head rx_batch;
+
+ struct timer_list rx_refill_timer;
+
+ /*
+ * {tx,rx}_skbs store outstanding skbuffs. The first entry in tx_skbs
+ * is an index into a chain of free entries.
+ */
+ struct sk_buff *tx_skbs[NET_TX_RING_SIZE+1];
+ struct sk_buff *rx_skbs[NET_RX_RING_SIZE];
+
+#define TX_MAX_TARGET min_t(int, NET_RX_RING_SIZE, 256)
+ grant_ref_t gref_tx_head;
+ grant_ref_t grant_tx_ref[NET_TX_RING_SIZE + 1];
+ grant_ref_t gref_rx_head;
+ grant_ref_t grant_rx_ref[NET_RX_RING_SIZE];
+
+ struct xenbus_device *xbdev;
+ int tx_ring_ref;
+ int rx_ring_ref;
+ u8 mac[ETH_ALEN];
+
+ unsigned long rx_pfn_array[NET_RX_RING_SIZE];
+ struct multicall_entry rx_mcl[NET_RX_RING_SIZE+1];
+ struct mmu_update rx_mmu[NET_RX_RING_SIZE];
+
+ /* Private pointer to state internal to accelerator module */
+ void *accel_priv;
+ /* The (list of) accelerator(s) used by this netfront device */
+ struct netfront_accelerator *accelerator;
+ /* The accelerator state for this netfront device */
+ struct netfront_accel_vif_state accel_vif_state;
+};
+
+
+/* Called by an accelerator plugin module when it has loaded.
+ *
+ * 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,
+ struct netfront_accel_hooks *hooks);
+
+/* Called when an accelerator plugin is ready to accelerate a device *
+ * that has been passed to it from netfront using the "new_device"
+ * hook.
+ *
+ * frontend: the string describing the accelerator. Must match the
+ * one passed to netfront_accelerator_loaded()
+ * dev: the xenbus device the plugin was asked to accelerate
+ */
+extern void netfront_accelerator_ready(const char *frontend,
+ struct xenbus_device *dev);
+
+/* Called by an accelerator plugin module when it is about to unload.
+ *
+ * frontend: the string describing the accelerator. Must match the
+ * one passed to netfront_accelerator_loaded()
+ */
+extern void netfront_accelerator_unloaded(const char *frontend);
+
+/* Called by an accelerator before waking the net device's TX queue to
+ * ensure the slow path has available slots. Returns true if OK to
+ * wake, false if still busy
+ */
+extern int netfront_check_queue_busy(struct net_device *net_dev);
+
+#endif /* NETFRONT_H */
frontend_accel
Description: Text document
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