RX devmem sometimes fails on NIPA:

https://netdev-3.bots.linux.dev/vmksft-fbnic-qemu-dbg/results/294402/7-devmem-py/

Both RSS and flow steering are properly installed, but the wait_port_listen
fails. Try to remove sleep(1) to see if the cause of the failure is
spending too much time during RX setup. I don't see a good reason to
have sleep in the first place. If there needs to be a delay between
installing the rules and receiving the traffic, let's add it to the
callers (devmem.py) instead.

Signed-off-by: Stanislav Fomichev <sdf@fomichev.me>
---
 tools/testing/selftests/drivers/net/hw/ncdevmem.c | 2 --
 1 file changed, 2 deletions(-)

diff --git a/tools/testing/selftests/drivers/net/hw/ncdevmem.c b/tools/testing/selftests/drivers/net/hw/ncdevmem.c
index c0a22938bed2..3288ed04ce08 100644
--- a/tools/testing/selftests/drivers/net/hw/ncdevmem.c
+++ b/tools/testing/selftests/drivers/net/hw/ncdevmem.c
@@ -872,8 +872,6 @@ static int do_server(struct memory_buffer *mem)
 		goto err_reset_rss;
 	}
 
-	sleep(1);
-
 	if (bind_rx_queue(ifindex, mem->fd, create_queues(), num_queues, &ys)) {
 		pr_err("Failed to bind");
 		goto err_reset_flow_steering;
-- 
2.51.0

On Fri, Sep 12, 2025 at 10:06 AM Stanislav Fomichev <sdf@fomichev.me> wrote:
>
> RX devmem sometimes fails on NIPA:
>
> https://netdev-3.bots.linux.dev/vmksft-fbnic-qemu-dbg/results/294402/7-devmem-py/
>
> Both RSS and flow steering are properly installed, but the wait_port_listen
> fails. Try to remove sleep(1) to see if the cause of the failure is
> spending too much time during RX setup.

OK, I can see that happening indeed.

> I don't see a good reason to
> have sleep in the first place. If there needs to be a delay between
> installing the rules and receiving the traffic, let's add it to the
> callers (devmem.py) instead.
>

Yeah, I was worried there would be something asynchronous about
installing flow steering rules (such as by the time when ethtool
returns, the rule is not yet fully active), that may cause some
flaky-iness, but that's unlikely the case.

> Signed-off-by: Stanislav Fomichev <sdf@fomichev.me>

Reviewed-by: Mina Almasry <almasrymina@google.com>


-- 
Thanks,
Mina