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Tue, 25 Aug 2026 10:09:45 -0400 (EDT) Date: Tue, 25 Aug 2026 07:09:44 -0700 From: Boqun Feng To: Radu Rendec Cc: Kuan-Wei Chiu , tglx@kernel.org, peterz@infradead.org, lyude@redhat.com, jserv@ccns.ncku.edu.tw, marscheng@google.com, eleanor15x@gmail.com, linux-kernel@vger.kernel.org Subject: Re: [PATCH] irq: Make refcount_interrupt kunit test selectable Message-ID: References: <20260823171721.3059733-1-visitorckw@gmail.com> <014ccedef7256efc027b8759134b9d1712d3afb6.camel@rendec.net> <0ae1284074ffda8681b08e8fdee50a413a163d4d.camel@rendec.net> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <0ae1284074ffda8681b08e8fdee50a413a163d4d.camel@rendec.net> On Mon, Aug 24, 2026 at 11:02:26AM -0400, Radu Rendec wrote: > On Sun, 2026-08-23 at 22:23 -0700, Boqun Feng wrote: > > On Sun, Aug 23, 2026 at 05:52:24PM -0400, Radu Rendec wrote: > > > On Sun, 2026-08-23 at 14:08 -0700, Boqun Feng wrote: > > > > On Sun, Aug 23, 2026 at 04:46:23PM -0400, Radu Rendec wrote: > > > > > On Sun, 2026-08-23 at 17:17 +0000, Kuan-Wei Chiu wrote: > > > > > > Currently, refcount_interrupt_test is built unconditionally when > > > > > > CONFIG_KUNIT is enabled, causing it to run unexpectedly during boot. > > > > > > > > > > > > Fix this by introducing CONFIG_REFCOUNT_INTERRUPT_KUNIT_TEST so the > > > > > > test can be configured independently, following standard kunit > > > > > > practices. > > > > > > > > > > > > Fixes: 07a88e2bcd5b ("irq: Add KUnit test for refcounted interrupt enable/disable") > > > > > > Signed-off-by: Kuan-Wei Chiu > > > > > > --- > > > > > >  kernel/irq/Kconfig  | 12 ++++++++++++ > > > > > >  kernel/irq/Makefile |  2 +- > > > > > >  2 files changed, 13 insertions(+), 1 deletion(-) > > > > > > > > > > Can someone please explain me why this needs to be a separate unit test > > > > > in the first place and can't be integrated into the (previously) > > > > > existing unit test gated by IRQ_KUNIT_TEST? > > > > > > > > > > > > > If you look at the irq_test.c, you will find that it primarily tests the > > > > {request,disable,enable}_irq() API (i.e. allocating IRQ vectors and > > > > enabling and disabling them), which is not the same scope as > > > > local_interrupt_{disable,enable}() (i.e. operating the CPU irq disabling > > > > status), so it makes sense to have a separate test case. > > > > > > Thanks! If we want to keep the unit tests separated/grouped by scope, > > > then yes, it makes sense for sure. What I don't like about this is: > > >  * The naming of the two config options is inconsistent: IRQ_KUNIT_TEST > > >    and REFCOUNT_INTERRUPT_KUNIT_TEST. > > >  * The naming and description of the older test become misleading. The > > >    way they are formulated, I would expect them to test "everything > > >    related to IRQ" but now we have a separate option (and kunit test) > > >    dedicated to the refcount stuff. > > > > > > > These are valid points. However, I think the "inconsistency" comes from > > refcount_interrupt_test.c being in kernel/irq/. IRQ management (code in > > kernel/irq/) and IRQ disabling/enabling are very different things to me > > I agree, they are different indeed, which is a good reason to keep the > tests separated as you pointed out. > > > (for example include/linux/irqflags.h is not listed in the "IRQ > > SUBSYSTEM" entry). > > It's not, and neither are a bunch of other IRQ related header files in > include/linux/ (get_maintainer.pl returns just the generic linux-kernel > mailing list). To me, that looks more like an omission, because it > means they have no maintainer. > > > IMO, refcount_interrupt_test.c should be moved into > > lib/tests/. > > I'm not sure about that. I looked, and and the tests in lib/tests/ are > for the stuff that's implemented in lib/*.c. On the other hand, most of Make sense. > the IRQ refcount code is in include/linux/interrupt_rc.h, with some > bits in kernel/softirq.c (e.g. the per-cpu state variable). If the IRQ > refcount code hadn't consisted of mostly static inline functions, where > would that code have been added? Still kernel/softirq.c? I'm thinking Yeah, I think that's the place (for example, local_interrupt_disable_state is defined here). > the corresponding unit tests belong in the same place, whatever that > is. Assuming kernel/softirq.c, I would have suggested to put the unit > tests in kernel/tests/, but it doesn't exist :) Right, I need to check whether we have other unit tests for kernel/ and maybe start a discussion on where to put them for now and future. > > > > If they must be separated/grouped by scope, I would find it much nicer > > > and less confusing if they were called something like: > > > IRQ_MANAGEMENT_KUNIT_TEST and > > > IRQ_REFCOUNT_KUNIT_TEST, > > > and also the corresponding .c files were somewhat consistent with the > > > Kconfig option names. The description of the older test would have to > > > be updated to make it clear that it's not just "everything IRQ". > > > > > > In that scenario, new kunit test(s) related to different aspects of the > > > IRQ subsystem would get their own Kconfig option and file, and would > > > hopefully follow the same naming pattern. > > > > > > To be clear, I'm not arguing that keeping the tests separate is wrong. > > > I'm arguing that if we do that, we should also make some adjustments to > > > keep everything clean and tidy. > > > > > > > Understood, and thank you for bringing it up. > > No problem. And thank you for not taking it the wrong way :) > Of course! Appreciate your input! > > So how about we keep Kuan-Wei's fix as it is and move the > > refcount_interrupt_test.c file into lib/tests/? It's more clean and tidy > > to me this way. Thoughts? > > I'm fine with taking Kuan-Wei's patch as it is. It fixes a real > problem, and the test code is already there (in kernel/irq/), it's not > like the patch is putting it there. Meanwhile, we can keep discussing > to find a better home for the test code and move it in a future patch. > I'll send a r-b tag separately. > Thank you! Regards, Boqun > > > > But yes, I agree Kuan-Wei's fix is needed. > > > > > > Yes, I agree, those unit tests must not be gated by KUNIT alone, so > > > something must be done to fix it. > > > > > > > > Ironically, both the issue that this patch is trying to fix and my > > > > > question were raised by sashiko here: > > > > > https://lore.kernel.org/all/20260605055315.3E96E1F00893@smtp.kernel.org/ > > > > > > > > > > > diff --git a/kernel/irq/Kconfig b/kernel/irq/Kconfig > > > > > > index 05cba4e16dad..6923f37eaab4 100644 > > > > > > --- a/kernel/irq/Kconfig > > > > > > +++ b/kernel/irq/Kconfig > > > > > > @@ -150,6 +150,18 @@ config IRQ_KUNIT_TEST > > > > > >   > > > > > >     If unsure, say N. > > > > > >   > > > > > > +config REFCOUNT_INTERRUPT_KUNIT_TEST > > > > > > + tristate "Test refcounted interrupt enable/disable" if !KUNIT_ALL_TESTS > > > > > > + depends on KUNIT > > > > > > + default KUNIT_ALL_TESTS > > > > > > + help > > > > > > +   This builds the kunit tests for the refcounted interrupt > > > > > > +   infrastructure. It verifies the correctness of single, nested, > > > > > > +   and multiple interrupt enable/disable state changes and ensures > > > > > > +   that the underlying reference counting mechanisms work as expected. > > > > > > + > > > > > > +   If unsure, say N. > > > > > > + > > > > > >  endmenu > > > > > >   > > > > > >  config GENERIC_IRQ_MULTI_HANDLER > > > > > > diff --git a/kernel/irq/Makefile b/kernel/irq/Makefile > > > > > > index 44c4d6fc502a..0e5df962a149 100644 > > > > > > --- a/kernel/irq/Makefile > > > > > > +++ b/kernel/irq/Makefile > > > > > > @@ -16,4 +16,4 @@ obj-$(CONFIG_SMP) += affinity.o > > > > > >  obj-$(CONFIG_GENERIC_IRQ_DEBUGFS) += debugfs.o > > > > > >  obj-$(CONFIG_GENERIC_IRQ_MATRIX_ALLOCATOR) += matrix.o > > > > > >  obj-$(CONFIG_IRQ_KUNIT_TEST) += irq_test.o > > > > > > -obj-$(CONFIG_KUNIT) += refcount_interrupt_test.o > > > > > > +obj-$(CONFIG_REFCOUNT_INTERRUPT_KUNIT_TEST) += refcount_interrupt_test.o > > > > -- > Best regards, > Radu