[3.11.y.z extended stable] Patch "iwl4965: better skb management in rx path" has been added to staging queue

[Luis Henriques]

This is a note to let you know that I have just added a patch titled

    iwl4965: better skb management in rx path

to the linux-3.11.y-queue branch of the 3.11.y.z extended stable tree 
which can be found at:

 http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.11.y-queue

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.11.y.z tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Luis

------

>From c1820dce1ba1c8874960c5e1b47e55923eb704b5 Mon Sep 17 00:00:00 2001
From: Stanislaw Gruszka <sgruszka at redhat.com>
Date: Mon, 1 Jul 2013 14:19:30 +0200
Subject: iwl4965: better skb management in rx path

commit c1de4a9557d9e25e41fc4ba034b9659152205539 upstream.

4965 version of Eric patch "iwl3945: better skb management in rx path".
It fixes several problems :

1) skb->truesize is underestimated.
   We really consume PAGE_SIZE bytes for a fragment,
   not the frame length.
2) 128 bytes of initial headroom is a bit low and forces reallocations.
3) We can avoid consuming a full page for small enough frames.

Signed-off-by: Stanislaw Gruszka <sgruszka at redhat.com>
Acked-by: Eric Dumazet <edumazet at google.com>
Signed-off-by: John W. Linville <linville at tuxdriver.com>
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
 drivers/net/wireless/iwlegacy/4965-mac.c | 18 ++++++++++++------
 1 file changed, 12 insertions(+), 6 deletions(-)

diff --git a/drivers/net/wireless/iwlegacy/4965-mac.c b/drivers/net/wireless/iwlegacy/4965-mac.c
index 7acf5ee..5ab50a5 100644
--- a/drivers/net/wireless/iwlegacy/4965-mac.c
+++ b/drivers/net/wireless/iwlegacy/4965-mac.c
@@ -574,9 +574,11 @@ il4965_translate_rx_status(struct il_priv *il, u32 decrypt_in)
 	return decrypt_out;
 }

+#define SMALL_PACKET_SIZE 256
+
 static void
 il4965_pass_packet_to_mac80211(struct il_priv *il, struct ieee80211_hdr *hdr,
-			       u16 len, u32 ampdu_status, struct il_rx_buf *rxb,
+			       u32 len, u32 ampdu_status, struct il_rx_buf *rxb,
 			       struct ieee80211_rx_status *stats)
 {
 	struct sk_buff *skb;
@@ -598,21 +600,25 @@ il4965_pass_packet_to_mac80211(struct il_priv *il, struct ieee80211_hdr *hdr,
 	    il_set_decrypted_flag(il, hdr, ampdu_status, stats))
 		return;

-	skb = dev_alloc_skb(128);
+	skb = dev_alloc_skb(SMALL_PACKET_SIZE);
 	if (!skb) {
 		IL_ERR("dev_alloc_skb failed\n");
 		return;
 	}

-	skb_add_rx_frag(skb, 0, rxb->page, (void *)hdr - rxb_addr(rxb), len,
-			len);
+	if (len <= SMALL_PACKET_SIZE) {
+		memcpy(skb_put(skb, len), hdr, len);
+	} else {
+		skb_add_rx_frag(skb, 0, rxb->page, (void *)hdr - rxb_addr(rxb),
+				len, PAGE_SIZE << il->hw_params.rx_page_order);
+		il->alloc_rxb_page--;
+		rxb->page = NULL;
+	}

 	il_update_stats(il, false, fc, len);
 	memcpy(IEEE80211_SKB_RXCB(skb), stats, sizeof(*stats));

 	ieee80211_rx(il->hw, skb);
-	il->alloc_rxb_page--;
-	rxb->page = NULL;
 }

 /* Called for N_RX (legacy ABG frames), or
--
1.8.3.2