Commit 45fe142c authored by Eric Dumazet's avatar Eric Dumazet Committed by John W. Linville
Browse files

iwl3945: better skb management in rx path 



Steinar reported reallocations of skb->head with IPv6, leading to
a warning in skb_try_coalesce()

It turns out iwl3945 has 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.

Reported-by: default avatarSteinar H. Gunderson <sesse@google.com>
Signed-off-by: default avatarEric Dumazet <edumazet@google.com>
Cc: Paul Stewart <pstew@google.com>
Acked-by: default avatarStanislaw Gruszka <sgruszka@redhat.com>
Signed-off-by: default avatarJohn W. Linville <linville@tuxdriver.com>
parent c6c7788f

drivers/net/wireless/iwlegacy/3945.c

+19 −12
Original line number Diff line number Diff line
@@ -475,6 +475,8 @@ il3945_is_network_packet(struct il_priv *il, struct ieee80211_hdr *header) 
	}

}



#define SMALL_PACKET_SIZE 256



static void

il3945_pass_packet_to_mac80211(struct il_priv *il, struct il_rx_buf *rxb,

			       struct ieee80211_rx_status *stats)
@@ -483,14 +485,13 @@ il3945_pass_packet_to_mac80211(struct il_priv *il, struct il_rx_buf *rxb, 
	struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)IL_RX_DATA(pkt);

	struct il3945_rx_frame_hdr *rx_hdr = IL_RX_HDR(pkt);

	struct il3945_rx_frame_end *rx_end = IL_RX_END(pkt);

	u16 len = le16_to_cpu(rx_hdr->len);

	u32 len = le16_to_cpu(rx_hdr->len);

	struct sk_buff *skb;

	__le16 fc = hdr->frame_control;

	u32 fraglen = PAGE_SIZE << il->hw_params.rx_page_order;



	/* We received data from the HW, so stop the watchdog */

	if (unlikely

	    (len + IL39_RX_FRAME_SIZE >

	     PAGE_SIZE << il->hw_params.rx_page_order)) {

	if (unlikely(len + IL39_RX_FRAME_SIZE > fraglen)) {

		D_DROP("Corruption detected!\n");

		return;

	}
@@ -506,26 +507,32 @@ il3945_pass_packet_to_mac80211(struct il_priv *il, struct il_rx_buf *rxb, 
		D_INFO("Woke queues - frame received on passive channel\n");

	}



	skb = dev_alloc_skb(128);

	skb = dev_alloc_skb(SMALL_PACKET_SIZE);

	if (!skb) {

		IL_ERR("dev_alloc_skb failed\n");

		return;

	}



	if (!il3945_mod_params.sw_crypto)

		il_set_decrypted_flag(il, (struct ieee80211_hdr *)rxb_addr(rxb),

		il_set_decrypted_flag(il, (struct ieee80211_hdr *)pkt,

				      le32_to_cpu(rx_end->status), stats);



	/* If frame is small enough to fit into skb->head, copy it

	 * and do not consume a full page

	 */

	if (len <= SMALL_PACKET_SIZE) {

		memcpy(skb_put(skb, len), rx_hdr->payload, len);

	} else {

		skb_add_rx_frag(skb, 0, rxb->page,

				(void *)rx_hdr->payload - (void *)pkt, len,

			len);



				fraglen);

		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;

}



#define IL_DELAY_NEXT_SCAN_AFTER_ASSOC (HZ*6)

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