Re: [PATCH v3 2/2] PCI/MSI: Implement irq_mask_noflush() for MSI-X

[Thomas Gleixner]

On Mon, Nov 09 2026 at 09:14, Keith Busch wrote:

> On Sat, Nov 07, 2026 at 10:53:47PM +0100, Thomas Gleixner wrote:
>> On Sat, Nov 07 2026 at 13:00, Keith Busch wrote:
>> > This is done on purpose: pci_msix_write_vector_ctrl() already has the
>> > same offline check, so nothing actually gets written, same as before.
>> >
>> > And regardless of whether it's offline or not, we have to set the
>> > PCI_MSIX_ENTRY_CTRL_MASKBIT in the cached msxi_ctrl. That's common to
>> > both paths, so it lives in the noflush helper to avoid duplicating it.
>> 
>> Indeed, but that's an unreadable mess TBH.
>
> No disagreement there! I was just going for a minimal diff, but we can
> refactor a bit on the way. I'll take a stab at it.

Yes, please. The minimal diff approch is what creates the most problems
down the road.

> I also don't really get the rationale for putting the check in
> write_vector. The commit message says the checks are to avoid having to
> deal with errors, but posted writes don't produce errors, so not sure
> what it's actually guarding against.

To me the explaination made sense and there were no objections within
month from any of the people involved. I'm not a DPC (or whatever is
involved) expert. I just work here.

I've Cc'ed the author of the patch for you as that might be a better way
to answer your question, no?

Thanks,

        tglx