Re: [PATCH v5 13/17] rv: Add KUnit mock for current

[Gabriele Monaco <gmonaco@redhat.com>]

Il 29 luglio 2026 18:17:31 UTC, Wen Yang <wen.yang@linux.dev> ha scritto:

>> +#define rv_get_current() (unlikely(kunit_get_current_test()) ? rv_get_mock_current() : current)
 
...

>> +/*
>> + * rv_get_mock_current() is called only if we are running from a KUnit test.
>> + * This can occur from a legitimate RV test or any unrelated test running when
>> + * a real RV monitor is active and triggering events.
>> + * We assume the former case is the only one where mock_current is not NULL and
>> + * can occur only sequentially (KUnit doesn't run tests in parallel).
>> + * We cannot rely on the test's context because there is no way to safely
>> + * understand from which test we are running and KUnit utilities require
>> + * locking, which is unsafe from NMI or scheduling context.
>> + * Note that it is not possible for a real RV monitor to run when the RV KUnit
>> + * tests are running (see rv_set_testing()).
>> + */
>> +static struct task_struct *mock_current;
>> +
>> +void rv_mock_current(struct task_struct *tsk)
>> +{
>> +	mock_current = tsk;
>> +}
>> +EXPORT_SYMBOL_IF_KUNIT(rv_mock_current);
>> +
>> +struct task_struct *rv_get_mock_current(void)
>> +{
>> +	return mock_current ?: current;
>> +}
>> +EXPORT_SYMBOL_GPL(rv_get_mock_current);
>>   #endif
>
>rv_mock_current() uses EXPORT_SYMBOL_IF_KUNIT, but rv_get_mock_current() uses EXPORT_SYMBOL_GPL. Both are defined inside the same CONFIG_RV_MONITORS_KUNIT_TEST block, so rv_get_mock_current should use EXPORT_SYMBOL_IF_KUNIT as well, otherwise it leaks a test-only symbol into production builds.
>
>With that fixed:
>Reviewed-by: Wen Yang <wen.yang@linux.dev>

Thanks for the review.
This was intentional however: rv_get_current() can be called by any monitor, those don't have to be KUnit.
Since rv_get_current() is a macro also calling rv_get_mock_current() we need to be able to link that too.

The idea is that a "real" (non-kunit) monitor handler could be run when interrupting a KUnit test (not an RV one, we make sure of that). In that case we do call rv_get_mock_current() and return current after the function call.

rv_mock_current() CANNOT be called outside of the RV KUnit test cases, it uses a global variable (for problems I tried to explain in the comment), so should be exported only to KUnit and called directly from the test case.

Does it make sense to you?

Thanks,
Gabriele