diff options
Diffstat (limited to 'drivers/net/wireless/rt2x00/rt2x00usb.c')
| -rw-r--r-- | drivers/net/wireless/rt2x00/rt2x00usb.c | 60 |
1 files changed, 42 insertions, 18 deletions
diff --git a/drivers/net/wireless/rt2x00/rt2x00usb.c b/drivers/net/wireless/rt2x00/rt2x00usb.c index caee65e82198..f72b3d07a42d 100644 --- a/drivers/net/wireless/rt2x00/rt2x00usb.c +++ b/drivers/net/wireless/rt2x00/rt2x00usb.c @@ -246,22 +246,35 @@ static struct sk_buff* rt2x00usb_alloc_rxskb(struct data_queue *queue) { struct sk_buff *skb; unsigned int frame_size; + unsigned int reserved_size; /* - * As alignment we use 2 and not NET_IP_ALIGN because we need - * to be sure we have 2 bytes room in the head. (NET_IP_ALIGN - * can be 0 on some hardware). We use these 2 bytes for frame - * alignment later, we assume that the chance that - * header_size % 4 == 2 is bigger then header_size % 2 == 0 - * and thus optimize alignment by reserving the 2 bytes in - * advance. + * The frame size includes descriptor size, because the + * hardware directly receive the frame into the skbuffer. */ frame_size = queue->data_size + queue->desc_size; - skb = dev_alloc_skb(queue->desc_size + frame_size + 2); + + /* + * For the allocation we should keep a few things in mind: + * 1) 4byte alignment of 802.11 payload + * + * For (1) we need at most 4 bytes to guarentee the correct + * alignment. We are going to optimize the fact that the chance + * that the 802.11 header_size % 4 == 2 is much bigger then + * anything else. However since we need to move the frame up + * to 3 bytes to the front, which means we need to preallocate + * 6 bytes. + */ + reserved_size = 6; + + /* + * Allocate skbuffer. + */ + skb = dev_alloc_skb(frame_size + reserved_size); if (!skb) return NULL; - skb_reserve(skb, queue->desc_size + 2); + skb_reserve(skb, reserved_size); skb_put(skb, frame_size); return skb; @@ -274,7 +287,8 @@ static void rt2x00usb_interrupt_rxdone(struct urb *urb) struct sk_buff *skb; struct skb_frame_desc *skbdesc; struct rxdone_entry_desc rxdesc; - int header_size; + unsigned int header_size; + unsigned int align; if (!test_bit(DEVICE_ENABLED_RADIO, &rt2x00dev->flags) || !test_and_clear_bit(ENTRY_OWNER_DEVICE_DATA, &entry->flags)) @@ -298,19 +312,29 @@ static void rt2x00usb_interrupt_rxdone(struct urb *urb) memset(&rxdesc, 0, sizeof(rxdesc)); rt2x00dev->ops->lib->fill_rxdone(entry, &rxdesc); + header_size = ieee80211_get_hdrlen_from_skb(entry->skb); + /* * The data behind the ieee80211 header must be - * aligned on a 4 byte boundary. + * aligned on a 4 byte boundary. We already reserved + * 2 bytes for header_size % 4 == 2 optimization. + * To determine the number of bytes which the data + * should be moved to the left, we must add these + * 2 bytes to the header_size. */ - header_size = ieee80211_get_hdrlen_from_skb(entry->skb); - if (header_size % 4 == 0) { - skb_push(entry->skb, 2); - memmove(entry->skb->data, entry->skb->data + 2, - entry->skb->len - 2); - skbdesc->data = entry->skb->data; - skb_trim(entry->skb,entry->skb->len - 2); + align = (header_size + 2) % 4; + + if (align) { + skb_push(entry->skb, align); + /* Move entire frame in 1 command */ + memmove(entry->skb->data, entry->skb->data + align, + rxdesc.size); } + /* Update data pointers, trim buffer to correct size */ + skbdesc->data = entry->skb->data; + skb_trim(entry->skb, rxdesc.size); + /* * Allocate a new sk buffer to replace the current one. * If allocation fails, we should drop the current frame |