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IPoIB: fix skb truesize underestimatiom

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Or Gerlitz reported triggering of WARN_ON_ONCE(delta < len); in
skb_try_coalesce()
This warning tracks drivers that incorrectly set skb->truesize

IPoIB indeed allocates a full page to store a fragment, but only
accounts in skb->truesize the used part of the page (frame length)

This patch fixes skb truesize underestimation, and
also fixes a performance issue, because RX skbs have not enough tailroom
to allow IP and TCP stacks to pull their header in skb linear part
without an expensive call to pskb_expand_head()

Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: Or Gerlitz <ogerlitz@mellanox.com>
Cc: Erez Shitrit <erezsh@mellanox.com>
Cc: Shlomo Pongartz <shlomop@mellanox.com>
Cc: Roland Dreier <roland@purestorage.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Eric Dumazet 2012-07-10 10:03:41 +00:00 committed by David S. Miller
parent efc73f4bbc
commit b28ba72665
1 changed files with 8 additions and 4 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

12
drivers/infiniband/ulp/ipoib/ipoib_ib.c
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@ -123,7 +123,7 @@ static void ipoib_ud_skb_put_frags(struct ipoib_dev_priv *priv,
skb_frag_size_set(frag, size);
skb->data_len += size;
skb->truesize += size;
skb->truesize += PAGE_SIZE;
} else
skb_put(skb, length);
@ -156,14 +156,18 @@ static struct sk_buff *ipoib_alloc_rx_skb(struct net_device *dev, int id)
struct ipoib_dev_priv *priv = netdev_priv(dev);
struct sk_buff *skb;
int buf_size;
int tailroom;
u64 *mapping;
if (ipoib_ud_need_sg(priv->max_ib_mtu))
if (ipoib_ud_need_sg(priv->max_ib_mtu)) {
buf_size = IPOIB_UD_HEAD_SIZE;
else
tailroom = 128; /* reserve some tailroom for IP/TCP headers */
} else {
buf_size = IPOIB_UD_BUF_SIZE(priv->max_ib_mtu);
tailroom = 0;
}
skb = dev_alloc_skb(buf_size + 4);
skb = dev_alloc_skb(buf_size + tailroom + 4);
if (unlikely(!skb))
return NULL;