Gitweb: http://git.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=d101f6...
Commit: d101f6496d51cbeb285f531dff059ce0ef28ffe3
Parent: a38db5b6219d88e2b48f07472c436b19b864f93c
Author: Ivo van Doorn <ivdoorn@gmail.com>
AuthorDate: Fri Jan 11 20:53:07 2008 +0100
Committer: John W. Linville <linville@tuxdriver.com>
CommitDate: Wed Jan 16 12:53:32 2008 -0500
rt2x00: Fix ieee80211 payload alignment
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>
---
drivers/net/wireless/rt2x00/rt2x00pci.c | 2 +-
drivers/net/wireless/rt2x00/rt2x00usb.c | 11 +++++++++--
2 files changed, 10 insertions(+), 3 deletions(-)
diff --git a/drivers/net/wireless/rt2x00/rt2x00pci.c b/drivers/net/wireless/rt2x00/rt2x00pci.c
index 6d5d9ab..04663eb 100644
--- a/drivers/net/wireless/rt2x00/rt2x00pci.c
+++ b/drivers/net/wireless/rt2x00/rt2x00pci.c
@@ -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
diff --git a/drivers/net/wireless/rt2x00/rt2x00usb.c b/drivers/net/wireless/rt2x00/rt2x00usb.c
index ab4797e..568d738 100644
--- a/drivers/net/wireless/rt2x00/rt2x00usb.c
+++ b/drivers/net/wireless/rt2x00/rt2x00usb.c
@@ -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);
/*
-
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