Subject: Re: [PATCH net-next v2] selftests: net: ksft: print more of the stack for checks

From: Petr Machata <[email-masked]>
Date: Wed, 31 Jul 2024 13:07:26 +0200

Jakub Kicinski <[email-masked]> writes:

> Print more stack frames and the failing line when check fails.
> This helps when tests use helpers to do the checks.
>
> Before:
>
>   # At ./ksft/drivers/net/hw/rss_ctx.py line 92:
>   # Check failed 1037698 >= 396893.0 traffic on other queues:[344612, 462380, 233020, 449174, 342298]
>   not ok 8 rss_ctx.test_rss_context_queue_reconfigure
>
> After:
>
>   # Check| At ./ksft/drivers/net/hw/rss_ctx.py, line 387, in test_rss_context_queue_reconfigure:
>   # Check|     test_rss_queue_reconfigure(cfg, main_ctx=False)
>   # Check| At ./ksft/drivers/net/hw/rss_ctx.py, line 230, in test_rss_queue_reconfigure:
>   # Check|     _send_traffic_check(cfg, port, ctx_ref, { 'target': (0, 3),
>   # Check| At ./ksft/drivers/net/hw/rss_ctx.py, line 92, in _send_traffic_check:
>   # Check|     ksft_lt(sum(cnts[i] for i in params['noise']), directed / 2,
>   # Check failed 1045235 >= 405823.5 traffic on other queues (context 1)':[460068, 351995, 565970, 351579, 127270]
>   not ok 8 rss_ctx.test_rss_context_queue_reconfigure
>
> Signed-off-by: Jakub Kicinski <[email-masked]>

Reviewed-by: Petr Machata <[email-masked]>

> diff --git a/tools/testing/selftests/net/lib/py/ksft.py b/tools/testing/selftests/net/lib/py/ksft.py
> index f26c20df9db4..707e0dfc7b9d 100644
> --- a/tools/testing/selftests/net/lib/py/ksft.py
> +++ b/tools/testing/selftests/net/lib/py/ksft.py
> @@ -32,8 +32,15 @@ KSFT_RESULT_ALL = True
>      global KSFT_RESULT
>      KSFT_RESULT = False
>  
> -    frame = inspect.stack()[2]
> -    ksft_pr("At " + frame.filename + " line " + str(frame.lineno) + ":")
> +    stack = inspect.stack()
> +    started = False
> +    for frame in reversed(stack[2:]):
> +        if not started:
> +            started |= frame.function == 'ksft_run'

Hmm, using bitwise operations on booleans is somewhat unusual in Python
I think, especially if here the short-circuiting of "or" wouldn't be a
problem. But it doesn't degrade to integers so I guess it's well-defined.

> +            continue
> +        ksft_pr("Check| At " + frame.filename + ", line " + str(frame.lineno) +
> +                ", in " + frame.function + ":")
> +        ksft_pr("Check|     " + frame.code_context[0].strip())
>      ksft_pr(*args)