@@ -556,32 +556,30 @@ static int rx_submit (struct usbnet *dev, struct urb *urb, gfp_t flags)
/*-------------------------------------------------------------------------*/
-static inline void rx_process (struct usbnet *dev, struct sk_buff *skb)
+static inline int rx_process(struct usbnet *dev, struct sk_buff *skb)
{
if (dev->driver_info->rx_fixup &&
!dev->driver_info->rx_fixup (dev, skb)) {
/* With RX_ASSEMBLE, rx_fixup() must update counters */
if (!(dev->driver_info->flags & FLAG_RX_ASSEMBLE))
dev->net->stats.rx_errors++;
- goto done;
+ return -EPROTO;
}
// else network stack removes extra byte if we forced a short packet
/* all data was already cloned from skb inside the driver */
if (dev->driver_info->flags & FLAG_MULTI_PACKET)
- goto done;
+ return -EALREADY;
if (skb->len < ETH_HLEN) {
dev->net->stats.rx_errors++;
dev->net->stats.rx_length_errors++;
netif_dbg(dev, rx_err, dev->net, "rx length %d\n", skb->len);
- } else {
- usbnet_skb_return(dev, skb);
- return;
+ return -EPROTO;
}
-done:
- skb_queue_tail(&dev->done, skb);
+ usbnet_skb_return(dev, skb);
+ return 0;
}
/*-------------------------------------------------------------------------*/
@@ -1515,6 +1513,14 @@ static int rx_alloc_submit(struct usbnet *dev, gfp_t flags)
return ret;
}
+static inline void usb_free_skb(struct sk_buff *skb)
+{
+ struct skb_data *entry = (struct skb_data *)skb->cb;
+
+ usb_free_urb(entry->urb);
+ dev_kfree_skb(skb);
+}
+
/*-------------------------------------------------------------------------*/
// tasklet (work deferred from completions, in_irq) or timer
@@ -1529,15 +1535,14 @@ static void usbnet_bh (struct timer_list *t)
entry = (struct skb_data *) skb->cb;
switch (entry->state) {
case rx_done:
- entry->state = rx_cleanup;
- rx_process (dev, skb);
+ if (rx_process(dev, skb))
+ usb_free_skb(skb);
continue;
case tx_done:
kfree(entry->urb->sg);
fallthrough;
case rx_cleanup:
- usb_free_urb (entry->urb);
- dev_kfree_skb (skb);
+ usb_free_skb(skb);
continue;
default:
netdev_dbg(dev->net, "bogus skb state %d\n", entry->state);
The current source pushes skb into dev-done queue by calling skb_dequeue_tail() and then pop it by skb_dequeue() to branch to rx_cleanup state for freeing urb/skb in usbnet_bh(). It takes extra CPU load, 2.21% (skb_queue_tail) as follows, - 11.58% 0.26% swapper [k] usbnet_bh - 11.32% usbnet_bh - 6.43% skb_dequeue 6.34% _raw_spin_unlock_irqrestore - 2.21% skb_queue_tail 2.19% _raw_spin_unlock_irqrestore - 1.68% consume_skb - 0.97% kfree_skbmem 0.80% kmem_cache_free 0.53% skb_release_data To reduce the extra CPU load use return values to call helper function usb_free_skb() to free the resources instead of calling skb_queue_tail() and skb_dequeue() for push and pop respectively. - 7.87% 0.25% swapper [k] usbnet_bh - 7.62% usbnet_bh - 4.81% skb_dequeue 4.74% _raw_spin_unlock_irqrestore - 1.75% consume_skb - 0.98% kfree_skbmem 0.78% kmem_cache_free 0.58% skb_release_data 0.53% smsc95xx_rx_fixup Signed-off-by: Leesoo Ahn <lsahn@ooseel.net> --- v4: - Use usb_free_skb() helper function instead of goto label v3: - Replace return values with proper -ERR values in rx_process() https://lore.kernel.org/netdev/20221221075924.1141346-1-lsahn@ooseel.net/ v2: - Replace goto label with return statement to reduce goto entropy - Add CPU load information by perf in commit message https://lore.kernel.org/netdev/20221221044230.1012787-1-lsahn@ooseel.net/ v1 at: https://lore.kernel.org/netdev/20221217161851.829497-1-lsahn@ooseel.net/ --- drivers/net/usb/usbnet.c | 29 +++++++++++++++++------------ 1 file changed, 17 insertions(+), 12 deletions(-)