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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: Steinar H. Gunderson <sesse@google.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Paul Stewart <pstew@google.com>
Acked-by: Stanislaw Gruszka <sgruszka@redhat.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
This commit is contained in:
Eric Dumazet 2013-06-28 08:05:06 -07:00 committed by John W. Linville
parent c6c7788fe2
commit 45fe142cef
1 changed files with 19 additions and 12 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

31
drivers/net/wireless/iwlegacy/3945.c
View File

@ -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)