mainlining shenanigans
a50e659b2a
The registration of XDP queue information is incorrect because the
RX queue id we use is invalid. When port->id == 0 it appears to works
as expected yet it's no longer the case when port->id != 0.
The problem arised while using a recent kernel version on the
MACCHIATOBin. This board has several ports:
* eth0 and eth1 are 10Gbps interfaces ; both ports has port->id == 0;
* eth2 is a 1Gbps interface with port->id != 0.
Code from xdp-tutorial (more specifically advanced03-AF_XDP) was used
to test packet capture and injection on all these interfaces. The XDP
kernel was simplified to:
SEC("xdp_sock")
int xdp_sock_prog(struct xdp_md *ctx)
{
int index = ctx->rx_queue_index;
/* A set entry here means that the correspnding queue_id
* has an active AF_XDP socket bound to it. */
if (bpf_map_lookup_elem(&xsks_map, &index))
return bpf_redirect_map(&xsks_map, index, 0);
return XDP_PASS;
}
Starting the program using:
./af_xdp_user -d DEV
Gives the following result:
* eth0 : ok
* eth1 : ok
* eth2 : no capture, no injection
Investigating the issue shows that XDP rx queues for eth2 are wrong:
XDP expects their id to be in the range [0..3] but we found them to be
in the range [32..35].
Trying to force rx queue ids using:
./af_xdp_user -d eth2 -Q 32
fails as expected (we shall not have more than 4 queues).
When we register the XDP rx queue information (using
xdp_rxq_info_reg() in function mvpp2_rxq_init()) we tell it to use
rxq->id as the queue id. This value is computed as:
rxq->id = port->id * max_rxq_count + queue_id
where max_rxq_count depends on the device version. In the MACCHIATOBin
case, this value is 32, meaning that rx queues on eth2 are numbered
from 32 to 35 - there are four of them.
Clearly, this is not the per-port queue id that XDP is expecting:
it wants a value in the range [0..3]. It shall directly use queue_id
which is stored in rxq->logic_rxq -- so let's use that value instead.
rxq->id is left untouched ; its value is indeed valid but it should
not be used in this context.
This is consistent with the remaining part of the code in
mvpp2_rxq_init().
With this change, packet capture is working as expected on all the
MACCHIATOBin ports.
Fixes:
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|---|---|---|
| arch | ||
| block | ||
| certs | ||
| crypto | ||
| Documentation | ||
| drivers | ||
| fs | ||
| include | ||
| init | ||
| ipc | ||
| kernel | ||
| lib | ||
| LICENSES | ||
| mm | ||
| net | ||
| samples | ||
| scripts | ||
| security | ||
| sound | ||
| tools | ||
| usr | ||
| virt | ||
| .clang-format | ||
| .cocciconfig | ||
| .get_maintainer.ignore | ||
| .gitattributes | ||
| .gitignore | ||
| .mailmap | ||
| COPYING | ||
| CREDITS | ||
| Kbuild | ||
| Kconfig | ||
| MAINTAINERS | ||
| Makefile | ||
| README | ||
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.