From: Petr Machata <petrm@nvidia•com>
To: Jakub Kicinski <kuba@kernel•org>
Cc: Petr Machata <petrm@nvidia•com>, <davem@davemloft•net>,
<netdev@vger•kernel.org>, <edumazet@google•com>,
<pabeni@redhat•com>, <andrew+netdev@lunn•ch>, <horms@kernel•org>,
<leitao@debian•org>, <jdamato@fastly•com>
Subject: Re: [PATCH net-next 2/2] selftests: net: py: ensure defer() is only used within a test case
Date: Fri, 9 Jan 2026 16:43:16 +0100 [thread overview]
Message-ID: <87344e6b7z.fsf@nvidia.com> (raw)
In-Reply-To: <20260109063938.3445c940@kernel.org>
Jakub Kicinski <kuba@kernel•org> writes:
> On Fri, 9 Jan 2026 09:23:54 +0100 Petr Machata wrote:
>> > I wasted a couple of hours recently after accidentally adding
>> > a defer() from within a function which itself was called as
>> > part of defer(). This leads to an infinite loop of defer().
>> > Make sure this cannot happen and raise a helpful exception.
>> >
>> > I understand that the pair of _ksft_defer_arm() calls may
>> > not be the most Pythonic way to implement this, but it's
>> > easy enough to understand.
>> >
>> > Signed-off-by: Jakub Kicinski <kuba@kernel•org>
>>
>> I think we achieve the same without the extra globals though? Just drain
>> the queue and walk through a copy of it?
>>
>> defer_queue = utils.GLOBAL_DEFER_QUEUE
>> utils.GLOBAL_DEFER_QUEUE = []
>> for i, entry in enumerate(defer_queue):
>> ...
>> if utils.GLOBAL_DEFER_QUEUE:
>> warning / exception
>
> That's what I had initially (IIUC), I was assigning None to the queue,
> and then [] only while inside a test case. It gets slightly hairy
> because either we need to pass in the queue into the flush function;
> or we have to restore the queue if something raises and exception during
> flush (in which case ksft_run() prints a warning and calls
> ksft_flush_defer() one more time).
Hmm, yeah, the exception robustness will complicate it. OK, let's have
it your way then :)
Reviewed-by: Petr Machata <petrm@nvidia•com>
next prev parent reply other threads:[~2026-01-09 15:46 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-01-08 22:52 [PATCH net-next 1/2] selftests: net: py: capitalize defer queue and improve import Jakub Kicinski
2026-01-08 22:52 ` [PATCH net-next 2/2] selftests: net: py: ensure defer() is only used within a test case Jakub Kicinski
2026-01-09 8:23 ` Petr Machata
2026-01-09 14:39 ` Jakub Kicinski
2026-01-09 15:43 ` Petr Machata [this message]
2026-01-09 8:38 ` [PATCH net-next 1/2] selftests: net: py: capitalize defer queue and improve import Petr Machata
2026-01-09 9:57 ` Breno Leitao
2026-01-12 20:57 ` patchwork-bot+netdevbpf
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