rt2x00: Add support for L2 padding during TX/RX

Some hardware require L2 padding between header and payload
because both must be aligned to a 4-byte boundary. This hardware
also is easier during the RX path since we no longer need to
move the entire payload but rather only the header to remove
the padding (mac80211 only wants the payload to be 4-byte aligned).

Signed-off-by: Ivo van Doorn <IvDoorn@gmail.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

1 files changed, 42 insertions, 26 deletions

diff --git a/drivers/net/wireless/rt2x00/rt2x00crypto.c b/drivers/net/wireless/rt2x00/rt2x00crypto.c
index ae31581372c0..57ab42cfed34 100644
--- a/drivers/net/wireless/rt2x00/rt2x00crypto.c
+++ b/drivers/net/wireless/rt2x00/rt2x00crypto.c
@@ -65,7 +65,7 @@ void rt2x00crypto_create_tx_descriptor(struct queue_entry *entry,
                 __set_bit(ENTRY_TXD_ENCRYPT_PAIRWISE, &txdesc->flags);
 
         txdesc->key_idx = hw_key->hw_key_idx;
-        txdesc->iv_offset = ieee80211_get_hdrlen_from_skb(entry->skb);
+        txdesc->iv_offset = txdesc->header_length;
         txdesc->iv_len = hw_key->iv_len;
 
         if (!(hw_key->flags & IEEE80211_KEY_FLAG_GENERATE_IV))
@@ -132,17 +132,16 @@ void rt2x00crypto_tx_remove_iv(struct sk_buff *skb, struct txentry_desc *txdesc)
         skb_pull(skb, txdesc->iv_len);
 
         /* IV/EIV data has officially be stripped */
-        skbdesc->flags |= FRAME_DESC_IV_STRIPPED;
+        skbdesc->flags |= SKBDESC_IV_STRIPPED;
 }
 
-void rt2x00crypto_tx_insert_iv(struct sk_buff *skb)
+void rt2x00crypto_tx_insert_iv(struct sk_buff *skb, unsigned int header_length)
 {
         struct skb_frame_desc *skbdesc = get_skb_frame_desc(skb);
-        unsigned int header_length = ieee80211_get_hdrlen_from_skb(skb);
         const unsigned int iv_len =
             ((!!(skbdesc->iv[0])) * 4) + ((!!(skbdesc->iv[1])) * 4);
 
-        if (!(skbdesc->flags & FRAME_DESC_IV_STRIPPED))
+        if (!(skbdesc->flags & SKBDESC_IV_STRIPPED))
                 return;
 
         skb_push(skb, iv_len);
@@ -154,14 +153,15 @@ void rt2x00crypto_tx_insert_iv(struct sk_buff *skb)
         memcpy(skb->data + header_length, skbdesc->iv, iv_len);
 
         /* IV/EIV data has returned into the frame */
-        skbdesc->flags &= ~FRAME_DESC_IV_STRIPPED;
+        skbdesc->flags &= ~SKBDESC_IV_STRIPPED;
 }
 
-void rt2x00crypto_rx_insert_iv(struct sk_buff *skb, unsigned int align,
+void rt2x00crypto_rx_insert_iv(struct sk_buff *skb, bool l2pad,
                                unsigned int header_length,
                                struct rxdone_entry_desc *rxdesc)
 {
         unsigned int payload_len = rxdesc->size - header_length;
+        unsigned int align = ALIGN_SIZE(skb, header_length);
         unsigned int iv_len;
         unsigned int icv_len;
         unsigned int transfer = 0;
@@ -191,32 +191,48 @@ void rt2x00crypto_rx_insert_iv(struct sk_buff *skb, unsigned int align,
         }
 
         /*
-         * Make room for new data, note that we increase both
-         * headsize and tailsize when required. The tailsize is
-         * only needed when ICV data needs to be inserted and
-         * the padding is smaller than the ICV data.
-         * When alignment requirements is greater than the
-         * ICV data we must trim the skb to the correct size
-         * because we need to remove the extra bytes.
+         * Make room for new data. There are 2 possibilities
+         * either the alignment is already present between
+         * the 802.11 header and payload. In that case we
+         * we have to move the header less then the iv_len
+         * since we can use the already available l2pad bytes
+         * for the iv data.
+         * When the alignment must be added manually we must
+         * move the header more then iv_len since we must
+         * make room for the payload move as well.
          */
-        skb_push(skb, iv_len + align);
-        if (align < icv_len)
-                skb_put(skb, icv_len - align);
-        else if (align > icv_len)
-                skb_trim(skb, rxdesc->size + iv_len + icv_len);
+        if (l2pad) {
+                skb_push(skb, iv_len - align);
+                skb_put(skb, icv_len);
 
-        /* Move ieee80211 header */
-        memmove(skb->data + transfer,
-                skb->data + transfer + iv_len + align,
-                header_length);
-        transfer += header_length;
+                /* Move ieee80211 header */
+                memmove(skb->data + transfer,
+                        skb->data + transfer + (iv_len - align),
+                        header_length);
+                transfer += header_length;
+        } else {
+                skb_push(skb, iv_len + align);
+                if (align < icv_len)
+                        skb_put(skb, icv_len - align);
+                else if (align > icv_len)
+                        skb_trim(skb, rxdesc->size + iv_len + icv_len);
+
+                /* Move ieee80211 header */
+                memmove(skb->data + transfer,
+                        skb->data + transfer + iv_len + align,
+                        header_length);
+                transfer += header_length;
+        }
 
         /* Copy IV/EIV data */
         memcpy(skb->data + transfer, rxdesc->iv, iv_len);
         transfer += iv_len;
 
-        /* Move payload */
-        if (align) {
+        /*
+         * Move payload for alignment purposes. Note that
+         * this is only needed when no l2 padding is present.
+         */
+        if (!l2pad) {
                 memmove(skb->data + transfer,
                         skb->data + transfer + align,
                         payload_len);