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rtlwifi: usb: add NET_IP_ALIGN padding to RX skb when needed

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Add proper alignment at first packet copy, to avoid extra copies made later
in networking stack.

Signed-off-by: Jussi Kivilinna <jussi.kivilinna@iki.fi>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
This commit is contained in:
Jussi Kivilinna 2013-03-17 11:59:29 +02:00 committed by John W. Linville
parent 29bb7013a5
commit 657e27656d
1 changed files with 40 additions and 1 deletions
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41
drivers/net/wireless/rtlwifi/usb.c
View file

@ -569,6 +569,37 @@ static void _rtl_rx_work(unsigned long param)
}
}
static unsigned int _rtl_rx_get_padding(struct ieee80211_hdr *hdr,
unsigned int len)
{
unsigned int padding = 0;
/* make function no-op when possible */
if (NET_IP_ALIGN == 0 || len < sizeof(*hdr))
return 0;
/* alignment calculation as in lbtf_rx() / carl9170_rx_copy_data() */
/* TODO: deduplicate common code, define helper function instead? */
if (ieee80211_is_data_qos(hdr->frame_control)) {
u8 *qc = ieee80211_get_qos_ctl(hdr);
padding ^= NET_IP_ALIGN;
/* Input might be invalid, avoid accessing memory outside
* the buffer.
*/
if ((unsigned long)qc - (unsigned long)hdr < len &&
*qc & IEEE80211_QOS_CTL_A_MSDU_PRESENT)
padding ^= NET_IP_ALIGN;
}
if (ieee80211_has_a4(hdr->frame_control))
padding ^= NET_IP_ALIGN;
return padding;
}
#define __RADIO_TAP_SIZE_RSV 32
static void _rtl_rx_completed(struct urb *_urb)
@ -582,9 +613,11 @@ static void _rtl_rx_completed(struct urb *_urb)
goto free;
if (likely(0 == _urb->status)) {
unsigned int padding;
struct sk_buff *skb;
unsigned int qlen;
unsigned int size = _urb->actual_length;
struct ieee80211_hdr *hdr;
if (size < RTL_RX_DESC_SIZE + sizeof(struct ieee80211_hdr)) {
RT_TRACE(rtlpriv, COMP_USB, DBG_EMERG,
@ -601,7 +634,10 @@ static void _rtl_rx_completed(struct urb *_urb)
goto resubmit;
}
skb = dev_alloc_skb(size + __RADIO_TAP_SIZE_RSV);
hdr = (void *)(_urb->transfer_buffer + RTL_RX_DESC_SIZE);
padding = _rtl_rx_get_padding(hdr, size - RTL_RX_DESC_SIZE);
skb = dev_alloc_skb(size + __RADIO_TAP_SIZE_RSV + padding);
if (!skb) {
RT_TRACE(rtlpriv, COMP_USB, DBG_EMERG,
"Can't allocate skb for bulk IN!\n");
@ -610,6 +646,9 @@ static void _rtl_rx_completed(struct urb *_urb)
_rtl_install_trx_info(rtlusb, skb, rtlusb->in_ep);
/* Make sure the payload data is 4 byte aligned. */
skb_reserve(skb, padding);
/* reserve some space for mac80211's radiotap */
skb_reserve(skb, __RADIO_TAP_SIZE_RSV);