Speaking as someone who's been involved in thousands of discussions over more than a decade evaluating issues like patent risk in consuming open source software, I don't see a patent clause in a CLA offering any realistic assurance to a downstream consumer.
Were I involved in a discussion around patent risk in DPDK, I would point to its license.
That said (and keeping in mind that IANAL), I do *not* see any patent protection in the BSD license similar to what one sees in the Apache 2 license, or the Eclipse Public License. Please note: I am not advocating here for a license change, just drawing attention to my perspective as someone who's been deeply involved in such things for a long time.
Ed