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

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Message-ID: <87msn587g7.fsf@nvidia.com>
Date: Fri, 28 Jun 2024 16:31:25 +0200
From: Petr Machata <petrm@...dia.com>
To: Jakub Kicinski <kuba@...nel.org>
CC: <davem@...emloft.net>, <netdev@...r.kernel.org>, <edumazet@...gle.com>,
	<pabeni@...hat.com>, <przemyslaw.kitszel@...el.com>, <petrm@...dia.com>,
	<willemdebruijn.kernel@...il.com>
Subject: Re: [PATCH net-next v2 2/3] selftests: drv-net: add ability to
 schedule cleanup with defer()


Jakub Kicinski <kuba@...nel.org> writes:

> 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>

Reviewed-by: Petr Machata <petrm@...dia.com>