Use a mutex for netback accelerators.

diff -r c61274a0a11c drivers/xen/netback/accel.c
--- a/drivers/xen/netback/accel.c	Mon Nov 05 13:02:31 2007 +0000
+++ b/drivers/xen/netback/accel.c	Mon Nov 05 13:48:06 2007 +0000
@@ -33,6 +33,7 @@
 #include <linux/list.h>
 #include <asm/atomic.h>
 #include <xen/xenbus.h>
+#include <linux/mutex.h>
 
 #include "common.h"
 
@@ -48,7 +49,7 @@
  */ 
 static struct list_head accelerators_list;
 /* Lock used to protect access to accelerators_list */
-static spinlock_t accelerators_lock;
+DEFINE_MUTEX(accelerators_mutex);
 
 /* 
  * Compare a backend to an accelerator, and decide if they are
@@ -107,7 +108,7 @@ int netback_connect_accelerator(unsigned
 				struct netback_accel_hooks *hooks)
 {
 	struct netback_accelerator *new_accelerator;
-	unsigned eth_name_len, flags;
+	unsigned eth_name_len;
 
 	if (version != NETBACK_ACCEL_VERSION) {
 		if (version > NETBACK_ACCEL_VERSION) {
@@ -149,9 +150,9 @@ int netback_connect_accelerator(unsigned
 
 	atomic_set(&new_accelerator->use_count, 0);
 	
-	spin_lock_irqsave(&accelerators_lock, flags);
+	mutex_lock(&accelerators_mutex);
 	list_add(&new_accelerator->link, &accelerators_list);
-	spin_unlock_irqrestore(&accelerators_lock, flags);
+	mutex_unlock(&accelerators_mutex);
 	
 	/* tell existing backends about new plugin */
 	xenbus_for_each_backend(new_accelerator, 
@@ -195,12 +196,12 @@ void netback_disconnect_accelerator(int 
 	struct netback_accelerator *accelerator, *next;
 	unsigned flags;
 
-	spin_lock_irqsave(&accelerators_lock, flags);
+	mutex_lock(&accelerators_mutex);
 	list_for_each_entry_safe(accelerator, next, &accelerators_list, link) {
 		if (strcmp(eth_name, accelerator->eth_name)) {
 			BUG_ON(atomic_read(&accelerator->use_count) != 0);
 			list_del(&accelerator->link);
-			spin_unlock_irqrestore(&accelerators_lock, flags);
+			mutex_unlock(&accelerators_mutex);
 
 			xenbus_for_each_backend(accelerator, 
 						netback_accelerator_cleanup_backend);
@@ -210,7 +211,7 @@ void netback_disconnect_accelerator(int 
 			return;
 		}
 	}
-	spin_unlock_irqrestore(&accelerators_lock, flags);
+	mutex_unlock(&accelerators_mutex);
 }
 EXPORT_SYMBOL_GPL(netback_disconnect_accelerator);
 
@@ -219,13 +220,12 @@ void netback_probe_accelerators(struct b
 				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);
+	mutex_lock(&accelerators_mutex);
 	list_for_each_entry(accelerator, &accelerators_list, link) { 
 		if (match_accelerator(dev, be, accelerator) &&
 		    try_module_get(accelerator->hooks->owner)) {
@@ -235,7 +235,7 @@ void netback_probe_accelerators(struct b
 			break;
 		}
 	}
-	spin_unlock_irqrestore(&accelerators_lock, flags);
+	mutex_unlock(&accelerators_mutex);
 }
 
 
@@ -255,5 +255,4 @@ void netif_accel_init(void)
 void netif_accel_init(void)
 {
 	INIT_LIST_HEAD(&accelerators_list);
-	spin_lock_init(&accelerators_lock);
-}
+}