On Fri, 2014-12-12 at 22:30 +0100, Thomas Jarosch wrote:

if it's any help: Disabling TX checksumming prevents the hang
even on an unpatched 3.14.x kernel. You could check with your debug statements
in place the path of the packets with and without TX checksumming.

Disabling TX checksum automatically disables GSO.

Disabling TSO/GSO is the real 'cure' for the time being, you can keep TX
checksums.