[PATCH 3.10 172/173] iwl4965: better skb management in rx path

Greg Kroah-Hartman
2013-12-02T19:12:35Z

From: Stanislaw Gruszka <sgruszka@redhat.com>

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@redhat.com>
Acked-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/net/wireless/iwlegacy/4965-mac.c | 18 ++++++++++++------
1 file changed, 12 insertions(+), 6 deletions(-)

--- 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_pri
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;
@@ -593,21 +595,25 @@ il4965_pass_packet_to_mac80211(struct il
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