Re: [PATCH net v2 4/4] selftests: drv-net: rss_ctx: test RSS contexts persist after ifdown/up

On Wed, Feb 11, 2026 at 9:47 AM Jakub Kicinski [off-list ref] wrote:

On Wed, 11 Feb 2026 09:28:22 +0530 Pavan Chebbi wrote:

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On Wed, Feb 11, 2026 at 7:16 AM Jakub Kicinski [off-list ref] wrote:

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I checked and tried using the cmd() and it indeed eliminates a lot of
lines here. But the test itself becomes a little unreliable.
I often see TimeoutError: [Errno Wait for file contents failed]
/sys/class/net/ens2f0np0/carrier from the wait_file (Jakub asked me to
use wait_file)

Does the link take more than the default 5 sec to come up?
wait_file() has a deadline param that should let us wait longer

I did try with increased deadline. But I don't think it's helping.

If you check the carrier manually in a second terminal while it's
running -- do you see it go to 1? The helper keeps the file open

Thanks for the nudge. I think I get the real issue now. It's not the
cmd() but ifup.exec()
I am using :
ifup = defer(ip, f"link set dev {cfg.ifname} up")
and later
ifup.exec()

I see that exec() takes unusually long time for carrier to go to 1.
Upto 20s and sometimes still fails.
Same with both direct exec or deferred. And this explains why I cannot
ping for long time after suite exists. Thats because I rely on defer()
to bring the interface up after bnxt exits with carrier 0 for the
second test.
If replace the exec with direct call to ip(f"link set dev {cfg.ifname}
up") I see it works reliably.

<-->

cmd() doesn't do any magic, it basically does:

        proc = subprocess.Popen(comm, shell=shell,
                                stdout=subprocess.PIPE, stderr=subprocess.PIPE,
                                pass_fds=pass_fds, env=env)
        proc.communicate(timeout)

So pretty much the same code as your subprocess.run().

It has support for communicating with extra fds to

Yes, sorry, this was a red herring for me