netdev - Re: [PATCH net-next v2 2/3] selftests: drv-net: add ability to schedule cleanup with defer()

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Date: Fri, 28 Jun 2024 14:35:10 +0200
From: Przemek Kitszel <przemyslaw.kitszel@...el.com>
To: Jakub Kicinski <kuba@...nel.org>
CC: <netdev@...r.kernel.org>, <edumazet@...gle.com>, <pabeni@...hat.com>,
	<petrm@...dia.com>, <davem@...emloft.net>, <willemdebruijn.kernel@...il.com>
Subject: Re: [PATCH net-next v2 2/3] selftests: drv-net: add ability to
 schedule cleanup with defer()

On 6/27/24 20:55, Jakub Kicinski wrote:
> This implements what I was describing in [1]. When writing a test
> author can schedule cleanup / undo actions right after the creation
> completes, eg:
> 
>    cmd("touch /tmp/file")
>    defer(cmd, "rm /tmp/file")
> 
> defer() takes the function name as first argument, and the rest are
> arguments for that function. defer()red functions are called in
> inverse order after test exits. It's also possible to capture them
> and execute earlier (in which case they get automatically de-queued).
> 
>    undo = defer(cmd, "rm /tmp/file")
>    # ... some unsafe code ...
>    undo.exec()
> 
> As a nice safety all exceptions from defer()ed calls are captured,
> printed, and ignored (they do make the test fail, however).
> This addresses the common problem of exceptions in cleanup paths
> often being unhandled, leading to potential leaks.
> 
> There is a global action queue, flushed by ksft_run(). We could support
> function level defers too, I guess, but there's no immediate need..
> 
> Link: https://lore.kernel.org/all/877cedb2ki.fsf@nvidia.com/ # [1]
> Signed-off-by: Jakub Kicinski <kuba@...nel.org>
> ---
> v2:
>   - split refactor to previous patch
>   - user bare except instead of except Exception
>   - rename _exec() -> exec_only() and use in flush
>   - reorder queue removal vs calling callback
>   - add print to indicate ID of failed callback
>   - remove the state flags
> ---
>   tools/testing/selftests/net/lib/py/ksft.py  | 21 +++++++++++++
>   tools/testing/selftests/net/lib/py/utils.py | 34 +++++++++++++++++++++
>   2 files changed, 55 insertions(+)
> 

nice improvement!
Reviewed-by: Przemek Kitszel <przemyslaw.kitszel@...el.com>