rtlwifi: usb: add NET_IP_ALIGN padding to RX skb when needed
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>
diff --git a/drivers/net/wireless/rtlwifi/usb.c b/drivers/net/wireless/rtlwifi/usb.c
index a7b54f6..72c2614 100644
--- a/drivers/net/wireless/rtlwifi/usb.c
+++ b/drivers/net/wireless/rtlwifi/usb.c
@@ -569,6 +569,37 @@
}
}
+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 @@
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 @@
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 @@
_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);