Add patches to fix iwl skb managment (rhbz 977040)

1 files changed, 97 insertions, 0 deletions

diff --git a/iwl3945-better-skb-management-in-rx-path.patch b/iwl3945-better-skb-management-in-rx-path.patch
new file mode 100644
index 000000000..5d85af7d4
--- /dev/null
+++ b/iwl3945-better-skb-management-in-rx-path.patch
@@ -0,0 +1,97 @@
+From: Eric Dumazet <edumazet@google.com>
+
+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: Steinar H. Gunderson <sesse@google.com>
+Signed-off-by: Eric Dumazet <edumazet@google.com>
+Cc: Paul Stewart <pstew@google.com>
+---
+v3: use regular memcpy(skb_put(...),...)
+v2: SMALL_PACKET_SIZE define
+
+ drivers/net/wireless/iwlegacy/3945.c |   31 +++++++++++++++----------
+ 1 file changed, 19 insertions(+), 12 deletions(-)
+
+diff --git a/drivers/net/wireless/iwlegacy/3945.c b/drivers/net/wireless/iwlegacy/3945.c
+index c092033..f09e257 100644
+--- a/drivers/net/wireless/iwlegacy/3945.c
++++ b/drivers/net/wireless/iwlegacy/3945.c
+@@ -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);
+ 
+-	skb_add_rx_frag(skb, 0, rxb->page,
+-			(void *)rx_hdr->payload - (void *)pkt, len,
+-			len);
+-
++	/* 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,
++				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)
+
+