wl1251: fix 4-byte TX buffer alignment

This implements TX buffer alignment for cloned or too small skb by
copying and replacing the original skb.
Recent changes in wireless-testing seems to make this really necessary.

Signed-off-by: David Gnedt <david.gnedt@davizone.at>
Acked-by: Kalle Valo <kvalo@adurom.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

1 files changed, 20 insertions, 6 deletions

diff --git a/drivers/net/wireless/wl1251/tx.c b/drivers/net/wireless/wl1251/tx.c
index 10112de55493..28121c590a2b 100644
--- a/drivers/net/wireless/wl1251/tx.c
+++ b/drivers/net/wireless/wl1251/tx.c
@@ -213,16 +213,30 @@ static int wl1251_tx_send_packet(struct wl1251 *wl, struct sk_buff *skb,
                 wl1251_debug(DEBUG_TX, "skb offset %d", offset);
 
                 /* check whether the current skb can be used */
-                if (!skb_cloned(skb) && (skb_tailroom(skb) >= offset)) {
-                        unsigned char *src = skb->data;
+                if (skb_cloned(skb) || (skb_tailroom(skb) < offset)) {
+                        struct sk_buff *newskb = skb_copy_expand(skb, 0, 3,
+                                                                 GFP_KERNEL);
+
+                        if (unlikely(newskb == NULL)) {
+                                wl1251_error("Can't allocate skb!");
+                                return -EINVAL;
+                        }
+
+                        tx_hdr = (struct tx_double_buffer_desc *) newskb->data;
+
+                        dev_kfree_skb_any(skb);
+                        wl->tx_frames[tx_hdr->id] = skb = newskb;
 
-                        /* align the buffer on a 4-byte boundary */
+                        offset = (4 - (long)skb->data) & 0x03;
+                        wl1251_debug(DEBUG_TX, "new skb offset %d", offset);
+                }
+
+                /* align the buffer on a 4-byte boundary */
+                if (offset) {
+                        unsigned char *src = skb->data;
                         skb_reserve(skb, offset);
                         memmove(skb->data, src, skb->len);
                         tx_hdr = (struct tx_double_buffer_desc *) skb->data;
-                } else {
-                        wl1251_info("No handler, fixme!");
-                        return -EINVAL;
                 }
         }