stmmac: limit max_mtu in case of 4KiB and use __netdev_alloc_skb (V2)
authorGiuseppe CAVALLARO <peppe.cavallaro@st.com>
Tue, 18 Oct 2011 01:39:55 +0000 (01:39 +0000)
committerDavid S. Miller <davem@davemloft.net>
Wed, 19 Oct 2011 23:24:18 +0000 (19:24 -0400)
commit45db81e1590c82ddc735ccd33f8adab02528b3e3
treec3438feab991a27b0d1a696c8118d5d28f414e03
parent286a837217204b1ef105e3a554d0757e4fdfaac1
stmmac: limit max_mtu in case of 4KiB and use __netdev_alloc_skb (V2)

Problem using big mtu around 4096 bytes is you end allocating (4096
+NET_SKB_PAD + NET_IP_ALIGN + sizeof(struct skb_shared_info) bytes ->
8192 bytes : order-1 pages

It's better to limit the mtu to SKB_MAX_HEAD(NET_SKB_PAD),
to have no more than one page per skb.

Also the patch changes the netdev_alloc_skb_ip_align() done in
init_dma_desc_rings() and uses a variant allowing GFP_KERNEL allocations
allowing the driver to load even in case of memory pressure.

Reported-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: Giuseppe Cavallaro <peppe.cavallaro@st.com>
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
drivers/net/ethernet/stmicro/stmmac/stmmac_main.c