[dpdk-users] How to use .last and .spec fields in the Generic Flow API?

Raslan Darawsheh rasland at mellanox.com
Thu Mar 7 09:51:40 CET 2019


Hi Andrew,

You are specifying a mask and the last for the item.
Based on the mask that you specified it means that match only the udp_dst_port that was specified since the mask is 0xffff
Which is causing conflicts with the range.
Try it without setting the mask or set the mask to be 0x0

Kindest regards,
Raslan Darawsheh

> -----Original Message-----
> From: users <users-bounces at dpdk.org> On Behalf Of Andrew Bainbridge
> Sent: Wednesday, March 6, 2019 5:30 PM
> To: users <users at dpdk.org>
> Subject: [dpdk-users] How to use .last and .spec fields in the Generic Flow
> API?
> 
> Hi
> 
> How should I specify a range of UDP ports in the generic flow API? Here's
> what I've tried...
> 
> I'm trying to create a flow to move packets with UDP dest ports from 1234 to
> 1244 into a specified queue. It works fine if I specify a single port of 1234,
> instead of the range. Here's how I set the flow item for that:
> 
>     struct rte_flow_item_udp udp_spec = { 0 };
>     struct rte_flow_item_udp udp_mask = { 0 };
>     udp_spec.hdr.dst_port = htons(udp_dst_port);
>     udp_mask.hdr.dst_port = 0xffff;
>     pattern[2].type = RTE_FLOW_ITEM_TYPE_UDP;
>     pattern[2].spec = &udp_spec;
>     pattern[2].mask = &udp_mask;
> 
> But if I attempt to specify the range, I believe I have to use the .last field.
> When I do that, I get this error, 'range between "spec" and "last" is larger
> than "mask"'. Here's how I set that flow item:
> 
>     struct rte_flow_item_udp udp_spec = { 0 };
>     struct rte_flow_item_udp udp_last = { 0 };
>     struct rte_flow_item_udp udp_mask = { 0 };
>     udp_spec.hdr.dst_port = htons(1234);
>     udp_last.hdr.dst_port = htons(1244);
>     udp_mask.hdr.dst_port = 0xffff;
>     pattern[2].type = RTE_FLOW_ITEM_TYPE_UDP;
>     pattern[2].spec = &udp_spec;
>     pattern[2].last = &udp_last;
>     pattern[2].mask = &udp_mask;
> 
> I don't understand the error message. The range between spec and last is 10.
> The mask is 0xffff. The error message seems wrong. But probably I just
> misunderstood something.
> 
> More details:
> 
> I'm using the mlx4 PMD. The source of the error message is in
> mlx4_flow_item_check(), where the code appears goes through each byte
> of the spec and last and checks that:
> 
>     (((const uint8_t *)item->spec)[i] & mask[i]) != (((const uint8_t *)item-
> >last)[i] & mask[i]))
> 
> Which makes no sense to me. That appears to require that spec and last are
> equal wherever mask is not zero.
> 
> Any ideas?
> 
> Thanks,
> Andy


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