From: Johannes Berg <johannes.b...@intel.com>
When we pre-populate the skb->head for the stack, we only pull
in the 802.11 header including crypto (assuming the packet isn't
short enough to be in there completely.) This is fine, but in
ieee80211_data_to_8023() we later unconditionally pull 8 more
bytes for the SNAP header and ethertype field (except for mesh
or 4-addr, where it's even more, but we don't care as much about
them).
Avoid the additional later pull by pulling in those 8 bytes here.
Signed-off-by: Johannes Berg <johannes.b...@intel.com>
Reviewed-by: IdoX Yariv <i...@wizery.com>
Signed-off-by: Emmanuel Grumbach <emmanuel.grumb...@intel.com>
---
drivers/net/wireless/iwlwifi/mvm/rx.c | 15 ++++++++++++---
1 file changed, 12 insertions(+), 3 deletions(-)
diff --git a/drivers/net/wireless/iwlwifi/mvm/rx.c
b/drivers/net/wireless/iwlwifi/mvm/rx.c
index 69fa765..94b6e72 100644
--- a/drivers/net/wireless/iwlwifi/mvm/rx.c
+++ b/drivers/net/wireless/iwlwifi/mvm/rx.c
@@ -104,10 +104,19 @@ static void iwl_mvm_pass_packet_to_mac80211(struct
iwl_mvm *mvm,
unsigned int hdrlen, fraglen;
/* If frame is small enough to fit in skb->head, pull it completely.
- * If not, only pull ieee80211_hdr (including crypto if present) so
- * that splice() or TCP coalesce are more efficient.
+ * If not, only pull ieee80211_hdr (including crypto if present, and
+ * an additional 8 bytes for SNAP/ethertype, see below) so that
+ * splice() or TCP coalesce are more efficient.
+ *
+ * Since, in addition, ieee80211_data_to_8023() always pull in at
+ * least 8 bytes (possibly more for mesh) we can do the same here
+ * to save the cost of doing it later. That still doesn't pull in
+ * the actual IP header since the typical case has a SNAP header.
+ * If the latter changes (there are efforts in the standards group
+ * to do so) we should revisit this and ieee80211_data_to_8023().
*/
- hdrlen = (len <= skb_tailroom(skb)) ? len : sizeof(*hdr) + crypt_len;
+ hdrlen = (len <= skb_tailroom(skb)) ? len :
+ sizeof(*hdr) + crypt_len + 8;
memcpy(skb_put(skb, hdrlen), hdr, hdrlen);
fraglen = len - hdrlen;
--
1.9.1
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