From d101f6496d51cbeb285f531dff059ce0ef28ffe3 Mon Sep 17 00:00:00 2001 From: Ivo van Doorn <ivdoorn@gmail.com> Date: Fri, 11 Jan 2008 20:53:07 +0100 Subject: [PATCH] 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 6d5d9aba0b73..04663eb31950 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 ab4797ed94c9..568d73847dca 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); /* -- GitLab