* build in headroom in __dev_alloc_skb() (linux/skbuff.h) and
* alloc_skb() (net/core/skbuff.c)
*/
- head_need = hdrlen + encaps_len + meshhdrlen + local->tx_headroom;
- head_need -= skb_headroom(skb);
+ head_need = hdrlen + encaps_len + meshhdrlen - skb_headroom(skb);
- /* We are going to modify skb data, so make a copy of it if happens to
- * be cloned. This could happen, e.g., with Linux bridge code passing
- * us broadcast frames. */
+ /*
+ * So we need to modify the skb header and hence need a copy of
+ * that. The head_need variable above doesn't, so far, include
+ * the needed header space that we don't need right away. If we
+ * can, then we don't reallocate right now but only after the
+ * frame arrives at the master device (if it does...)
+ *
+ * If we cannot, however, then we will reallocate to include all
+ * the ever needed space. Also, if we need to reallocate it anyway,
+ * make it big enough for everything we may ever need.
+ */
- if (head_need > 0 || skb_header_cloned(skb)) {
+ if (head_need > 0 || skb_cloned(skb)) {
-#if 0
- printk(KERN_DEBUG "%s: need to reallocate buffer for %d bytes "
- "of headroom\n", dev->name, head_need);
-#endif
-
- if (skb_cloned(skb))
- I802_DEBUG_INC(local->tx_expand_skb_head_cloned);
- else
- I802_DEBUG_INC(local->tx_expand_skb_head);
- /* Since we have to reallocate the buffer, make sure that there
- * is enough room for possible WEP IV/ICV and TKIP (8 bytes
- * before payload and 12 after). */
- if (pskb_expand_head(skb, (head_need > 0 ? head_need + 8 : 8),
- 12, GFP_ATOMIC)) {
- printk(KERN_DEBUG "%s: failed to reallocate TX buffer"
- "\n", dev->name);
+ head_need += IEEE80211_ENCRYPT_HEADROOM;
+ head_need += local->tx_headroom;
+ head_need = max_t(int, 0, head_need);
+ if (ieee80211_skb_resize(local, skb, head_need, true))
goto fail;
- }
}
if (encaps_data) {