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rt2x00: Fix ieee80211 payload alignment

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As Johannes Berg indicated, the NET_IP_ALIGN doesn't
need to be used for ieee80211 frames. This means we
can simplify the alignment calculation to just
use the result of the header size modulus 4 as frame
alignment.

Furthermore we shouldn't use NET_IP_ALIGN in rt2x00usb
because it could be 0 on some architectures and we absolutely
need to have 2 bytes reserved for possible aligning.

Signed-off-by: Ivo van Doorn<IvDoorn@gmail.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
This commit is contained in:
Ivo van Doorn 2008-01-11 20:53:07 +01:00 committed by John W. Linville
parent a38db5b621
commit d101f6496d
2 changed files with 10 additions and 3 deletions
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2
drivers/net/wireless/rt2x00/rt2x00pci.c
View file

@ -149,7 +149,7 @@ void rt2x00pci_rxdone(struct rt2x00_dev *rt2x00dev)
* The data behind the ieee80211 header must be
* aligned on a 4 byte boundary.
*/
align = NET_IP_ALIGN + (2 * (header_size % 4 == 0));
align = header_size % 4;
/*
* Allocate the sk_buffer, initialize it and copy

11
drivers/net/wireless/rt2x00/rt2x00usb.c
View file

@ -245,13 +245,20 @@ static void rt2x00usb_interrupt_rxdone(struct urb *urb)
* Allocate a new sk buffer to replace the current one.
* If allocation fails, we should drop the current frame
* so we can recycle the existing sk buffer for the new frame.
* 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.
*/
frame_size = entry->ring->data_size + entry->ring->desc_size;
skb = dev_alloc_skb(frame_size + NET_IP_ALIGN);
skb = dev_alloc_skb(frame_size + 2);
if (!skb)
goto skip_entry;
skb_reserve(skb, NET_IP_ALIGN);
skb_reserve(skb, 2);
skb_put(skb, frame_size);
/*