On Thu, 2015-01-15 at 18:37 +0100, Thomas Jarosch wrote:

On Thursday, 15. January 2015 09:20:37 Eric Dumazet wrote:

quoted

quoted

for the sake of completeness:
1: hang

This is weird : This should have same effect then GRO off (at most one
segment per packet)

I thought so, too. OTOH the code path was changed from
"goto merge" to "return -E2BIG". I didn't look at the code
what happens at the "merge" label.

If you leave the "goto merge", then GRO still builds big GRO packets,
using a linked list of packets.

Then because drivers do not generally support NETIF_F_FRAGLIST,
core networking code linearizes such GRO packets before reaching
ndo_start_xmit()

Check 8a29111c7ca68d928dfab58636f3f6acf0ac04f7 "net: gro: allow to build
full sized skb" for details about this.