[PATCH 2/9 Rev3] [core] Add skb_blist & hard_start_xmit_batch

Krishna Kumar
2007-08-08T09:30:54Z

Introduce skb_blist and hard_start_xmit_batch API, handle driver's usage
of the new API, and add support routines.

Signed-off-by: Krishna Kumar <krkumar2@in.ibm.com>
---
include/linux/netdevice.h | 8 +++
net/core/dev.c | 98 ++++++++++++++++++++++++++++++++++++++++++++++
2 files changed, 106 insertions(+)

diff -ruNp ORG/include/linux/netdevice.h NEW/include/linux/netdevice.h
--- ORG/include/linux/netdevice.h 2007-08-06 08:25:37.000000000 +0530
+++ NEW/include/linux/netdevice.h 2007-08-07 13:11:19.000000000 +0530
@@ -456,6 +456,9 @@ struct net_device
/* Partially transmitted GSO packet. */
struct sk_buff *gso_skb;

+ /* List of batch skbs (optional, used if driver supports batching API */
+ struct sk_buff_head *skb_blist;
+
/* ingress path synchronizer */
spinlock_t ingress_lock;
struct Qdisc *qdisc_ingress;
@@ -472,6 +475,9 @@ struct net_device
void *priv; /* pointer to private data */
int (*hard_start_xmit) (struct sk_buff *skb,
struct net_device *dev);
+ int (*hard_start_xmit_batch) (struct net_device
+ *dev);
+
/* These may be needed for future network-power-down code. */
unsigned long trans_start; /* Time (in jiffies) of last Tx */

@@ -832,6 +838,8 @@ extern int dev_set_mac_address(struct n
struct sockaddr *);
extern int dev_hard_start_xmit(struct sk_buff *skb,
struct net_device *dev);
+extern int dev_add_skb_to_blist(struct sk_buff *skb,
+ struct net_device *dev);

extern void dev_init(void);

diff -ruNp ORG/net/core/dev.c NEW/net/core/dev.c
--- ORG/net/core/dev.c 2007-08-06 08:25:40.000000000 +0530
+++ NEW/net/core/dev.c 2007-08-07 13:11:19.000000000 +0530
@@ -897,6 +897,55 @@ void netdev_state_change(struct net_devi
}
}

+static void free_batching(struct net_device *dev)
+{
+ if (dev->skb_blist) {
+ if (!skb_queue_empty(dev->skb_blist))
+ skb_queue_purge(dev->skb_blist);
+ kfree(dev->skb_blist);
+ dev->skb_blist = NULL;
+ }
+}
+
+int dev_change_tx_batch_skb(struct net_device *dev, unsigned long new_batch_skb)
+{
+ int ret = 0;
+ struct sk_buff_head *blist;
+
+ if (!dev->hard_start_xmit_batch) {
+ /* Driver doesn't support batching skb API */
+ ret = -ENOTSUPP;
+ goto out;
+ }
+
+ /* Handle invalid argument */
+ if (new_batch_skb < 0) {
+ ret = -EINVAL;
+ goto out;
+ }
+
+ /* Check if new value is same as the current */
+ if (!!dev->skb_blist == !!new_batch_skb)
+ goto out;
+
+ if (new_batch_skb &&
+ (blist = kmalloc(sizeof *blist, GFP_KERNEL)) == NULL) {
+ ret = -ENOMEM;
+ goto out;
+ }
+
+ spin_lock(&dev->queue_lock);
+ if (new_batch_skb) {
+ skb_queue_head_init(blist);
+ dev->skb_blist = blist;
+ } else
+ free_batching(dev);
+ spin_unlock(&dev->queue_lock);
+
+out:
+ return ret;
+}
+
/**
* dev_load - load a network module
* @name: name of interface
@@ -1459,6 +1508,45 @@ static int dev_gso_segment(struct sk_buf
return 0;
}

+/*
+ * Add skb (skbs in case segmentation is required) to dev->skb_blist. We are
+ * holding QDISC RUNNING bit, so no one else can add to this list. Also, skbs
+ * are dequeued from this list when we call the driver, so the list is safe
+ * from simultaneous deletes too.
+ *
+ * Returns count of successful skb(s) added to skb_blist.
+ */
+int dev_add_skb_to_blist(struct sk_buff *skb, struct net_device *dev)
+{
+ if (!list_empty(&ptype_all))
+ dev_queue_xmit_nit(skb, dev);
+
+ if (netif_needs_gso(dev, skb)) {
+ if (unlikely(dev_gso_segment(skb))) {
+ kfree(skb);
+ return 0;
+ }
+
+ if (skb->next) {
+ int count = 0;
+
+ do {
+ struct sk_buff *nskb = skb->next;
+
+ skb->next = nskb->next;
+ __skb_queue_tail(dev->skb_blist, nskb);
+ count++;
+ } while (skb->next);
+
+ skb->destructor = DEV_GSO_CB(skb)->destructor;
+ kfree_skb(skb);
+ return count;
+ }
+ }
+ __skb_queue_tail(dev->skb_blist, skb);
+ return 1;
+}
+
int dev_hard_start_xmit(struct sk_buff *skb, struct net_device *dev)
{
if (likely(!skb->next)) {
@@ -3446,6 +3535,13 @@ int register_netdevice(struct net_device
}
}

+ if (dev->hard_start_xmit_batch) {
+ /* Driver supports batching skb API */
+ dev->skb_blist = kmalloc(sizeof *dev->skb_blist, GFP_KERNEL);
+ if (dev->skb_blist)
+ skb_queue_head_init(dev->skb_blist);
+ }
+
/*
* nil rebuild_header routine,
* that should be never called and used as just bug trap.
@@ -3787,6 +3882,9 @@ void unregister_netdevice(struct net_dev

synchronize_net();

+ /* Deallocate batching structure */
+ free_batching(dev);
+
/* Shutdown queueing discipline. */
dev_shutdown(dev);