Jakub Kicinski wrote:
> Most of our tests use rtnetlink to read device stats, so they
> don't expose the drivers much to paths in which device stats
> are read under RCU. Add tests which hammer profcs reads to
> make sure drivers:
> - don't sleep while reporting stats,
> - can handle parallel reads,
> - can handle device going down while reading.
>
> Set ifname on the env class in NetDrvEnv, we already do that
> in NetDrvEpEnv.
>
> KTAP version 1
> 1..7
> ok 1 stats.check_pause
> ok 2 stats.check_fec
> ok 3 stats.pkt_byte_sum
> ok 4 stats.qstat_by_ifindex
> ok 5 stats.check_down
> ok 6 stats.procfs_hammer
> # completed up/down cycles: 6
> ok 7 stats.procfs_downup_hammer
> # Totals: pass:7 fail:0 xfail:0 xpass:0 skip:0 error:0
>
> Signed-off-by: Jakub Kicinski <kuba@xxxxxxxxxx>
Reviewed-by: Willem de Bruijn <willemb@xxxxxxxxxx>
Two tiny comments, neither cause for respin.
> +@ksft_disruptive
> +def procfs_downup_hammer(cfg) -> None:
> + """
> + Reading stats via procfs only holds the RCU lock, drivers often try
> + to sleep when reading the stats, or don't protect against races.
> + """
> + # Max out the queues, we'll flip between max an 1
s/an/and/
> + channels = ethnl.channels_get({'header': {'dev-index': cfg.ifindex}})
> + if channels['combined-count'] == 0:
> + rx_type = 'rx'
> + else:
> + rx_type = 'combined'
> + cur_queue_cnt = channels[f'{rx_type}-count']
> + max_queue_cnt = channels[f'{rx_type}-max']
> +
> + cmd(f"ethtool -L {cfg.ifname} {rx_type} {max_queue_cnt}")
> + defer(cmd, f"ethtool -L {cfg.ifname} {rx_type} {cur_queue_cnt}")
> +
> + # Real test stats
> + stats = __run_inf_loop("cat /proc/net/dev")
> + defer(stats.kill)
> +
> + ipset = f"ip link set dev {cfg.ifname}"
> + defer(ip, f"link set dev {cfg.ifname} up")
unimportant: could reference ipset here too, as in below.
> + # The "echo -n 1" lets us count iterations below
> + updown = f"{ipset} down; sleep 0.05; {ipset} up; sleep 0.05; " + \
> + f"ethtool -L {cfg.ifname} {rx_type} 1; " + \
> + f"ethtool -L {cfg.ifname} {rx_type} {max_queue_cnt}; " + \
> + "echo -n 1"
