WARNING - OLD ARCHIVES

This is an archived copy of the Xen.org mailing list, which we have preserved to ensure that existing links to archives are not broken. The live archive, which contains the latest emails, can be found at http://lists.xen.org/
   
 
 
Xen 
 
Home Products Support Community News
 
   
 

xen-devel

[Xen-devel] [PATCH 3/4] [Net] Support accelerated network plugin modules

To: xen-devel@xxxxxxxxxxxxxxxxxxx
Subject: [Xen-devel] [PATCH 3/4] [Net] Support accelerated network plugin modules
From: Kieran Mansley <kmansley@xxxxxxxxxxxxxx>
Date: Mon, 09 Jul 2007 13:09:45 +0100
Delivery-date: Mon, 09 Jul 2007 05:09:15 -0700
Envelope-to: www-data@xxxxxxxxxxxxxxxxxx
List-help: <mailto:xen-devel-request@lists.xensource.com?subject=help>
List-id: Xen developer discussion <xen-devel.lists.xensource.com>
List-post: <mailto:xen-devel@lists.xensource.com>
List-subscribe: <http://lists.xensource.com/cgi-bin/mailman/listinfo/xen-devel>, <mailto:xen-devel-request@lists.xensource.com?subject=subscribe>
List-unsubscribe: <http://lists.xensource.com/cgi-bin/mailman/listinfo/xen-devel>, <mailto:xen-devel-request@lists.xensource.com?subject=unsubscribe>
Sender: xen-devel-bounces@xxxxxxxxxxxxxxxxxxx
Backend net driver acceleration

Signed-off-by: Kieran Mansley <kmansley@xxxxxxxxxxxxxx>

diff -r 30c836e0575e drivers/xen/netback/Makefile
--- a/drivers/xen/netback/Makefile      Fri Jun 15 15:35:17 2007 +0100
+++ b/drivers/xen/netback/Makefile      Fri Jun 15 15:37:41 2007 +0100
@@ -1,5 +1,5 @@ obj-$(CONFIG_XEN_NETDEV_BACKEND) := netb
 obj-$(CONFIG_XEN_NETDEV_BACKEND) := netbk.o
 obj-$(CONFIG_XEN_NETDEV_LOOPBACK) += netloop.o
 
-netbk-y   := netback.o xenbus.o interface.o
+netbk-y   := netback.o xenbus.o interface.o accel.o
 netloop-y := loopback.o
diff -r 30c836e0575e drivers/xen/netback/accel.c
--- /dev/null   Thu Jan 01 00:00:00 1970 +0000
+++ b/drivers/xen/netback/accel.c       Wed Jun 20 14:58:09 2007 +0100
@@ -0,0 +1,207 @@
+/******************************************************************************
+ * drivers/xen/netback/accel.c
+ *
+ * Interface between backend virtual network device and accelerated plugin. 
+ * 
+ * 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.
+ */
+
+#include <linux/list.h>
+#include <asm/atomic.h>
+#include <xen/xenbus.h>
+
+#include "common.h"
+
+#if 0
+#undef DPRINTK
+#define DPRINTK(fmt, args...)                                          \
+       printk("netback/accel (%s:%d) " fmt ".\n", __FUNCTION__, __LINE__, 
##args)
+#endif
+
+/* 
+ * 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
+        */
+       return be->accelerator == NULL;
+}
+
+/*
+ * 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;
+                       atomic_inc(&be->accelerator->use_count);
+                       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) {
+               DPRINTK("%s: failed to allocate memory for accelerator\n",
+                       __FUNCTION__);
+               return;
+       }
+
+       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;
+
+       atomic_set(&new_accelerator->use_count, 0);
+       
+       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);
+
+}
+EXPORT_SYMBOL_GPL(netback_connect_accelerator);
+
+
+/* 
+ * Disconnect an accerator 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.  This is enforced through a
+ * usage count and BUG_ON(use!=0), but should be made more user-friendly
+ */
+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)) {
+                       BUG_ON(atomic_read(&accelerator->use_count) != 0);
+                       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);
+
+
+void netback_probe_accelerators(struct backend_info *be,
+                               struct xenbus_device *dev)
+{
+       struct netback_accelerator *accelerator;
+       unsigned flags;
+
+       /* 
+        * 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;
+                       atomic_inc(&be->accelerator->use_count);
+                       be->accelerator->hooks->probe(dev);
+                       break;
+               }
+       }
+       spin_unlock_irqrestore(&accelerators_lock, flags);
+}
+
+
+void netback_remove_accelerators(struct backend_info *be,
+                                struct xenbus_device *dev)
+{
+       /* Notify the accelerator (if any) of this device's removal */
+       if ( be->accelerator ) {
+               be->accelerator->hooks->remove(dev);
+               atomic_dec(&be->accelerator->use_count);
+       }
+       be->accelerator = NULL;
+}
+
+
+void netif_accel_init(void)
+{
+       INIT_LIST_HEAD(&accelerators_list);
+       spin_lock_init(&accelerators_lock);
+}
diff -r 30c836e0575e drivers/xen/netback/common.h
--- a/drivers/xen/netback/common.h      Fri Jun 15 15:35:17 2007 +0100
+++ b/drivers/xen/netback/common.h      Mon Jun 18 09:30:21 2007 +0100
@@ -45,6 +45,7 @@
 #include <xen/interface/grant_table.h>
 #include <xen/gnttab.h>
 #include <xen/driver_util.h>
+#include <xen/xenbus.h>
 
 #define DPRINTK(_f, _a...)                     \
        pr_debug("(file=%s, line=%d) " _f,      \
@@ -122,6 +123,49 @@ enum {
 
 extern int netbk_copy_skb_mode;
 
+/* 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;
+       atomic_t use_count;
+       struct netback_accel_hooks *hooks;
+};
+
+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;
+};
+
+/* 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);
+
+
+extern
+void netback_probe_accelerators(struct backend_info *be,
+                               struct xenbus_device *dev);
+extern
+void netback_remove_accelerators(struct backend_info *be,
+                                struct xenbus_device *dev);
+extern
+void netif_accel_init(void);
+
+
 #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 30c836e0575e drivers/xen/netback/netback.c
--- a/drivers/xen/netback/netback.c     Fri Jun 15 15:35:17 2007 +0100
+++ b/drivers/xen/netback/netback.c     Mon Jun 18 09:30:21 2007 +0100
@@ -1587,6 +1587,8 @@ static int __init netback_init(void)
                        netbk_copy_skb_mode = NETBK_DELAYED_COPY_SKB;
        }
 
+       netif_accel_init();
+
        netif_xenbus_init();
 
 #ifdef NETBE_DEBUG_INTERRUPT
diff -r 30c836e0575e drivers/xen/netback/xenbus.c
--- a/drivers/xen/netback/xenbus.c      Fri Jun 15 15:35:17 2007 +0100
+++ b/drivers/xen/netback/xenbus.c      Wed Jun 20 14:58:20 2007 +0100
@@ -28,11 +28,6 @@
     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;
-};
 
 static int connect_rings(struct backend_info *);
 static void connect(struct backend_info *);
@@ -41,6 +36,8 @@ static int netback_remove(struct xenbus_
 static int netback_remove(struct xenbus_device *dev)
 {
        struct backend_info *be = dev->dev.driver_data;
+
+       netback_remove_accelerators(be, dev);
 
        if (be->netif) {
                netif_disconnect(be->netif);
@@ -125,6 +122,8 @@ static int netback_probe(struct xenbus_d
                goto fail;
        }
 
+       netback_probe_accelerators(be, dev);
+
        err = xenbus_switch_state(dev, XenbusStateInitWait);
        if (err)
                goto fail;

Attachment: backend_accel
Description: Text document

_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-devel
<Prev in Thread] Current Thread [Next in Thread>
  • [Xen-devel] [PATCH 3/4] [Net] Support accelerated network plugin modules, Kieran Mansley <=