[PATCH] net: Add netdev_alloc_skb_ip_align() helper
From: Eric Dumazet <hidden>
Date: 2009-10-08 03:12:14
Also in:
lkml
Subsystem:
networking [general], the rest · Maintainers:
"David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Linus Torvalds
Thomas Chou a écrit :
quoted hunk ↗ jump to hunk
As suggested by Stephen Hemminger. Signed-off-by: Thomas Chou <redacted> --- drivers/net/ethoc.c | 2 +- 1 files changed, 1 insertions(+), 1 deletions(-)diff --git a/drivers/net/ethoc.c b/drivers/net/ethoc.c index ecc53d9..4a1ed81 100644 --- a/drivers/net/ethoc.c +++ b/drivers/net/ethoc.c@@ -409,7 +409,7 @@ static int ethoc_rx(struct net_device *dev, int limit) struct sk_buff *skb = netdev_alloc_skb(dev, size); size -= 4; /* strip the CRC */ - skb_reserve(skb, 2); /* align TCP/IP header */ + skb_reserve(skb, NET_IP_ALIGN); if (likely(skb)) { void *src = phys_to_virt(bd.addr);
Sorry to be dense here, but this code breaks if NET_IP_ALIGN > 4.
Its also suboptimal, you alloc two bytes in excess.
You should do :
size -= 4; /* strip the CRC */
skb = netdev_alloc_skb(dev, size + NET_IP_ALIGN);
if (skb) {
skb_reserve(skb, NET_IP_ALIGN);
...
}
Please check other implementations...
David, maybe we should add following helper :
[PATCH] net: Add netdev_alloc_skb_ip_align() helper
Instead of hardcoding NET_IP_ALIGN stuff in various network drivers, we can
add a helper around netdev_alloc_skb()
Signed-off-by: Eric Dumazet <redacted>
---diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index df7b23a..fed788e 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h@@ -1489,6 +1489,16 @@ static inline struct sk_buff *netdev_alloc_skb(struct net_device *dev, return __netdev_alloc_skb(dev, length, GFP_ATOMIC); } +static inline struct sk_buff *netdev_alloc_skb_ip_align(struct net_device *dev, + unsigned int length) +{ + struct sk_buff *skb = netdev_alloc_skb(dev, length + NET_IP_ALIGN); + + if (NET_IP_ALIGN && skb) + skb_reserve(skb, NET_IP_ALIGN); + return skb; +} + extern struct page *__netdev_alloc_page(struct net_device *dev, gfp_t gfp_mask); /**