From: Keir Fraser <keir.fraser@citrix.com>
Date: Thu, 20 Dec 2007 16:58:14 +0000 (+0000)
Subject: netfront accel: Over-eager locking meant kmalloc at GFP_KERNEL with irqs disabled
X-Git-Tag: xen-3.2.0~41
X-Git-Url: http://xenbits.xensource.com/gitweb?a=commitdiff_plain;h=89f3e1800534d35c05e145a838f72690e39941c5;p=legacy%2Flinux-2.6.18-xen.git

netfront accel: Over-eager locking meant kmalloc at GFP_KERNEL with irqs disabled
Signed-off-by Kieran Mansley <kmansley@solarflare.com>
---

diff --git a/drivers/xen/netfront/accel.c b/drivers/xen/netfront/accel.c
index 78491c69..ebef91cd 100644
--- a/drivers/xen/netfront/accel.c
+++ b/drivers/xen/netfront/accel.c
@@ -273,6 +273,7 @@ static int init_accelerator(const char *frontend,
 {
 	struct netfront_accelerator *accelerator = 
 		kmalloc(sizeof(struct netfront_accelerator), GFP_KERNEL);
+	unsigned long flags;
 	int frontend_len;
 
 	if (!accelerator) {
@@ -294,7 +295,9 @@ static int init_accelerator(const char *frontend,
 
 	accelerator->hooks = hooks;
 
+	spin_lock_irqsave(&accelerators_lock, flags);
 	list_add(&accelerator->link, &accelerators_list);
+	spin_unlock_irqrestore(&accelerators_lock, flags);
 
 	*result = accelerator;
 
@@ -365,20 +368,15 @@ static int netfront_load_accelerator(struct netfront_info *np,
 {
 	struct netfront_accelerator *accelerator;
 	int rc = 0;
-	unsigned long flags;
 
 	DPRINTK(" %s\n", frontend);
 
-	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)) {
-			spin_unlock_irqrestore(&accelerators_lock, flags);
-
 			accelerator_probe_new_vif(np, dev, accelerator);
 			return 0;
 		}
@@ -386,12 +384,9 @@ static int netfront_load_accelerator(struct netfront_info *np,
 
 	/* Couldn't find it, so create a new one and load the module */
 	if ((rc = init_accelerator(frontend, &accelerator, NULL)) < 0) {
-		spin_unlock_irqrestore(&accelerators_lock, flags);
 		return rc;
 	}
 
-	spin_unlock_irqrestore(&accelerators_lock, flags);
-
 	/* Include this frontend device on the accelerator's list */
 	add_accelerator_vif(accelerator, np);
 
@@ -450,7 +445,6 @@ int netfront_accelerator_loaded(int version, const char *frontend,
 				struct netfront_accel_hooks *hooks)
 {
 	struct netfront_accelerator *accelerator;
-	unsigned long flags;
 
 	if (version != NETFRONT_ACCEL_VERSION) {
 		if (version > NETFRONT_ACCEL_VERSION) {
@@ -469,18 +463,13 @@ int netfront_accelerator_loaded(int version, const char *frontend,
 
 	mutex_lock(&accelerator_mutex);
 
-	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)) {
-			spin_unlock_irqrestore(&accelerators_lock, flags);
-
 			accelerator_probe_vifs(accelerator, hooks);
-
 			goto out;
 		}
 	}
@@ -494,8 +483,6 @@ int netfront_accelerator_loaded(int version, const char *frontend,
 
 	init_accelerator(frontend, &accelerator, hooks);
 
-	spin_unlock_irqrestore(&accelerators_lock, flags);
-
  out:
 	mutex_unlock(&accelerator_mutex);
 	return 0;