Subject: skbufhead-raw-lock.patch
From: Thomas Gleixner <tglx@linutronix.de>
Date: Tue, 12 Jul 2011 15:38:34 +0200

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
---
 include/linux/netdevice.h |    1 +
 include/linux/skbuff.h    |    7 +++++++
 net/core/dev.c            |   26 ++++++++++++++++++++------
 3 files changed, 28 insertions(+), 6 deletions(-)

Index: linux-stable/include/linux/netdevice.h
===================================================================
--- linux-stable.orig/include/linux/netdevice.h
+++ linux-stable/include/linux/netdevice.h
@@ -1765,6 +1765,7 @@ struct softnet_data {
 	unsigned int		dropped;
 	struct sk_buff_head	input_pkt_queue;
 	struct napi_struct	backlog;
+	struct sk_buff_head	tofree_queue;
 };
 
 static inline void input_queue_head_incr(struct softnet_data *sd)
Index: linux-stable/include/linux/skbuff.h
===================================================================
--- linux-stable.orig/include/linux/skbuff.h
+++ linux-stable/include/linux/skbuff.h
@@ -132,6 +132,7 @@ struct sk_buff_head {
 
 	__u32		qlen;
 	spinlock_t	lock;
+	raw_spinlock_t	raw_lock;
 };
 
 struct sk_buff;
@@ -992,6 +993,12 @@ static inline void skb_queue_head_init(s
 	__skb_queue_head_init(list);
 }
 
+static inline void skb_queue_head_init_raw(struct sk_buff_head *list)
+{
+	raw_spin_lock_init(&list->raw_lock);
+	__skb_queue_head_init(list);
+}
+
 static inline void skb_queue_head_init_class(struct sk_buff_head *list,
 		struct lock_class_key *class)
 {
Index: linux-stable/net/core/dev.c
===================================================================
--- linux-stable.orig/net/core/dev.c
+++ linux-stable/net/core/dev.c
@@ -221,14 +221,14 @@ static inline struct hlist_head *dev_ind
 static inline void rps_lock(struct softnet_data *sd)
 {
 #ifdef CONFIG_RPS
-	spin_lock(&sd->input_pkt_queue.lock);
+	raw_spin_lock(&sd->input_pkt_queue.raw_lock);
 #endif
 }
 
 static inline void rps_unlock(struct softnet_data *sd)
 {
 #ifdef CONFIG_RPS
-	spin_unlock(&sd->input_pkt_queue.lock);
+	raw_spin_unlock(&sd->input_pkt_queue.raw_lock);
 #endif
 }
 
@@ -3402,7 +3402,7 @@ static void flush_backlog(void *arg)
 	skb_queue_walk_safe(&sd->input_pkt_queue, skb, tmp) {
 		if (skb->dev == dev) {
 			__skb_unlink(skb, &sd->input_pkt_queue);
-			kfree_skb(skb);
+			__skb_queue_tail(&sd->tofree_queue, skb);
 			input_queue_head_incr(sd);
 		}
 	}
@@ -3411,10 +3411,13 @@ static void flush_backlog(void *arg)
 	skb_queue_walk_safe(&sd->process_queue, skb, tmp) {
 		if (skb->dev == dev) {
 			__skb_unlink(skb, &sd->process_queue);
-			kfree_skb(skb);
+			__skb_queue_tail(&sd->tofree_queue, skb);
 			input_queue_head_incr(sd);
 		}
 	}
+
+	if (!skb_queue_empty(&sd->tofree_queue))
+		raise_softirq_irqoff(NET_RX_SOFTIRQ);
 }
 
 static int napi_gro_complete(struct sk_buff *skb)
@@ -3903,10 +3906,17 @@ static void net_rx_action(struct softirq
 	struct softnet_data *sd = &__get_cpu_var(softnet_data);
 	unsigned long time_limit = jiffies + 2;
 	int budget = netdev_budget;
+	struct sk_buff *skb;
 	void *have;
 
 	local_irq_disable();
 
+	while ((skb = __skb_dequeue(&sd->tofree_queue))) {
+		local_irq_enable();
+		kfree_skb(skb);
+		local_irq_disable();
+	}
+
 	while (!list_empty(&sd->poll_list)) {
 		struct napi_struct *n;
 		int work, weight;
@@ -6337,6 +6347,9 @@ static int dev_cpu_callback(struct notif
 		netif_rx(skb);
 		input_queue_head_incr(oldsd);
 	}
+	while ((skb = __skb_dequeue(&oldsd->tofree_queue))) {
+		kfree_skb(skb);
+	}
 
 	return NOTIFY_OK;
 }
@@ -6601,8 +6614,9 @@ static int __init net_dev_init(void)
 		struct softnet_data *sd = &per_cpu(softnet_data, i);
 
 		memset(sd, 0, sizeof(*sd));
-		skb_queue_head_init(&sd->input_pkt_queue);
-		skb_queue_head_init(&sd->process_queue);
+		skb_queue_head_init_raw(&sd->input_pkt_queue);
+		skb_queue_head_init_raw(&sd->process_queue);
+		skb_queue_head_init_raw(&sd->tofree_queue);
 		sd->completion_queue = NULL;
 		INIT_LIST_HEAD(&sd->poll_list);
 		sd->output_queue = NULL;