Hi Magnus,
On 5/12/23 11:20 AM, Magnus Karlsson wrote:
Prepare the AF_XDP selftests test framework code for the upcoming
multi-buffer support in AF_XDP. This so that the multi-buffer patch
set does not become way too large. In that upcoming patch set, we are
only including the multi-buffer tests together with any framework
code that depends on the new options bit introduced in the AF_XDP
multi-buffer implementation itself.
Currently, the test framework is based on the premise that a packet
consists of a single fragment and thus occupies a single buffer and a
single descriptor. Multi-buffer breaks this assumption, as that is the
whole purpose of it. Now, a packet can consist of multiple buffers and
therefore consume multiple descriptors.
The patch set starts with some clean-ups and simplifications followed
by patches that make sure that the current code works even when a
packet occupies multiple buffers. The actual code for sending and
receiving multi-buffer packets will be included in the AF_XDP
multi-buffer patch set as it depends on a new bit being used in the
options field of the descriptor.
Patch set anatomy:
1: The XDP program was unnecessarily changed many times. Fixes this.
2: There is no reason to generate a full UDP/IPv4 packet as it is
never used. Simplify the code by just generating a valid Ethernet
frame.
3: Introduce a more complicated payload pattern that can detect
fragments out of bounds in a multi-buffer packet and other errors
found in single-fragment packets.
4: As a convenience, dump the content of the faulty packet at error.
5: To simplify the code, make the usage of the packet stream for Tx
and Rx more similar.
6: Store the offset of the packet in the buffer in the struct pkt
definition instead of the address in the umem itself and introduce
a simple buffer allocator. The address only made sense when all
packets consumed a single buffer. Now, we do not know beforehand
how many buffers a packet will consume, so we instead just allocate
a buffer from the allocator and specify the offset within that
buffer.
7: Test for huge pages only once instead of before each test that needs it.
8: Populate the fill ring based on how many frags are needed for each
packet.
9: Change the data generation code so it can generate data for
multi-buffer packets too.
10: Adjust the packet pacing algorithm so that it can cope with
multi-buffer packets. The pacing algorithm is present so that Tx
does not send too many packets/frames to Rx that it starts to drop
packets. That would ruin the tests.
This triggers build error in BPF CI:
https://github.com/kernel-patches/bpf/actions/runs/4984982413/jobs/8924047266
[...]
xskxceiver.c:1881:2: error: variable 'ret' is used uninitialized whenever switch default is taken [-Werror,-Wsometimes-uninitialized]
default:
^~~~~~~
xskxceiver.c:1885:6: note: uninitialized use occurs here
if (ret == TEST_PASS)
^~~
xskxceiver.c:1779:9: note: initialize the variable 'ret' to silence this warning
GEN-SKEL [test_progs] test_subskeleton.skel.h
GEN-SKEL [test_progs] test_subskeleton_lib.skel.h
int ret;
^
= 0
1 error generated.
make: *** [Makefile:617: /tmp/work/bpf/bpf/tools/testing/selftests/bpf/xskxceiver] Error 1
make: *** Waiting for unfinished jobs....
GEN-SKEL [test_progs] test_usdt.skel.h
make: Leaving directory '/tmp/work/bpf/bpf/tools/testing/selftests/bpf'
Pls fix and respin, thanks.
