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

From: Thomas Gleixner <tglx@linutronix.de>

Use the rps lock as rawlock so we can keep irq-off regions. It looks low
latency. However we can't kfree() from this context therefore we defer this
to the softirq and use the tofree_queue list for it (similar to process_queue).

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>


---
 include/linux/skbuff.h |    7 +++++++
 net/core/dev.c         |    6 +++---
 2 files changed, 10 insertions(+), 3 deletions(-)
---
@ include/linux/skbuff.h:300 @ struct sk_buff_head {
 
 	__u32		qlen;
 	spinlock_t	lock;
+	raw_spinlock_t	raw_lock;
 };
 
 struct sk_buff;
@ include/linux/skbuff.h:1920 @ 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)
 {
--- a/net/core/dev.c
+++ b/net/core/dev.c
@ include/linux/skbuff.h:228 @ 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
 }
 
@ include/linux/skbuff.h:11629 @ static int __init net_dev_init(void)
 
 		INIT_WORK(flush, flush_backlog);
 
-		skb_queue_head_init(&sd->input_pkt_queue);
+		skb_queue_head_init_raw(&sd->input_pkt_queue);
 		skb_queue_head_init(&sd->process_queue);
 #ifdef CONFIG_XFRM_OFFLOAD
 		skb_queue_head_init(&sd->xfrm_backlog);