linux-kernel - Re: [PATCH v2] kunit: Enforce task execution in {soft,hard}irq contexts

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Message-ID: <20251219190547.GB1602@sol>
Date: Fri, 19 Dec 2025 11:05:47 -0800
From: Eric Biggers <ebiggers@...nel.org>
To: David Gow <davidgow@...gle.com>
Cc: Brendan Higgins <brendan.higgins@...ux.dev>,
	Rae Moar <raemoar63@...il.com>,
	Shuah Khan <skhan@...uxfoundation.org>,
	linux-kselftest@...r.kernel.org, kunit-dev@...glegroups.com,
	linux-kernel@...r.kernel.org, linux-crypto@...r.kernel.org
Subject: Re: [PATCH v2] kunit: Enforce task execution in {soft,hard}irq
 contexts

On Fri, Dec 19, 2025 at 04:52:58PM +0800, David Gow wrote:
> The kunit_run_irq_test() helper allows a function to be run in hardirq
> and softirq contexts (in addition to the task context). It does this by
> running the user-provided function concurrently in the three contexts,
> until either a timeout has expired or a number of iterations have
> completed in the normal task context.
> 
> However, on setups where the initialisation of the hardirq and softirq
> contexts (or, indeed, the scheduling of those tasks) is significantly
> slower than the function execution, it's possible for that number of
> iterations to be exceeded before any runs in irq contexts actually
> occur. This occurs with the polyval.test_polyval_preparekey_in_irqs
> test, which runs 20000 iterations of the relatively fast preparekey
> function, and therefore fails often under many UML, 32-bit arm, m68k and
> other environments.
> 
> Instead, ensure that the max_iterations limit counts executions in all
> three contexts, and requires at least one of each. This will cause the
> test to continue iterating until at least the irq contexts have been
> tested, or the 1s wall-clock limit has been exceeded. This causes the
> test to pass in all of my environments.
> 
> In so doing, we also update the task counters to atomic ints, to better
> match both the 'int' max_iterations input, and to ensure they are
> correctly updated across contexts.
> 
> Finally, we also fix a few potential assertion messages to be
> less-specific to the original crypto usecases.
> 
> Fixes: b41dc83f0790 ("kunit, lib/crypto: Move run_irq_test() to common header")
> Signed-off-by: David Gow <davidgow@...gle.com>
> ---
> 
> Changes since v1:
> https://lore.kernel.org/all/20251219080850.921416-1-davidgow@google.com/
> - Remove a leftover debug line which forced max_iterations to 1.

Thanks!  I'd like to take this through libcrypto-fixes, if that's okay
with the KUnit folks (acks would be appreciated).  kunit_run_irq_test()
is a recently-added helper function used by the crypto and CRC tests.

For the Fixes commit, we should use the initial addition of this code:

    Fixes: 950a81224e8b ("lib/crypto: tests: Add hash-test-template.h and gen-hash-testvecs.py")

- Eric