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| author | Raimonds Cicans <ray@apollo.lv> | 2009-11-13 10:52:19 +0000 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@suse.de> | 2010-04-01 15:52:18 -0700 |
| commit | e2db86fdddfbf179ebc8e717b50770cf7acf78b6 (patch) | |
| tree | 6672ccc787fa8a4d0e54a6d5342e5a0a73fa6037 /drivers | |
| parent | 5d0698d14afc8179e681d1baa6a76a814f8f2fcf (diff) | |
| download | lwn-e2db86fdddfbf179ebc8e717b50770cf7acf78b6.tar.gz lwn-e2db86fdddfbf179ebc8e717b50770cf7acf78b6.zip | |
r8169: Fix receive buffer length when MTU is between 1515 and 1536
commit 8812304cf1110ae16b0778680f6022216cf4716a upstream.
In r8169 driver MTU is used to calculate receive buffer size.
Receive buffer size is used to configure hardware incoming packet filter.
For jumbo frames:
Receive buffer size = Max frame size = MTU + 14 (ethernet header) + 4
(vlan header) + 4 (ethernet checksum) = MTU + 22
Bug:
driver for all MTU up to 1536 use receive buffer size 1536
As you can see from formula, this mean all IP packets > 1536 - 22
(for vlan tagged, 1536 - 18 for not tagged) are dropped by hardware
filter.
Example:
host_good> ifconfig eth0 mtu 1536
host_r8169> ifconfig eth0 mtu 1536
host_good> ping host_r8169
Ok
host_good> ping -s 1500 host_r8169
Fail
host_good> ifconfig eth0 mtu 7000
host_r8169> ifconfig eth0 mtu 7000
host_good> ping -s 1500 host_r8169
Ok
Bonus: got rid of magic number 8
Signed-off-by: Raimonds Cicans <ray@apollo.lv>
Signed-off-by: David S. Miller <davem@davemloft.net>
Cc: Jean Delvare <khali@linux-fr.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Diffstat (limited to 'drivers')
| -rw-r--r-- | drivers/net/r8169.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/drivers/net/r8169.c b/drivers/net/r8169.c index f71821552533..68bba7f9a648 100644 --- a/drivers/net/r8169.c +++ b/drivers/net/r8169.c @@ -1842,9 +1842,9 @@ static void __devexit rtl8169_remove_one(struct pci_dev *pdev) static void rtl8169_set_rxbufsize(struct rtl8169_private *tp, struct net_device *dev) { - unsigned int mtu = dev->mtu; + unsigned int max_frame = dev->mtu + VLAN_ETH_HLEN + ETH_FCS_LEN; - tp->rx_buf_sz = (mtu > RX_BUF_SIZE) ? mtu + ETH_HLEN + 8 : RX_BUF_SIZE; + tp->rx_buf_sz = (max_frame > RX_BUF_SIZE) ? max_frame : RX_BUF_SIZE; } static int rtl8169_open(struct net_device *dev) |