On Thu, Oct 29 2020 at 09:42, Heiner Kallweit wrote:
> On 29.10.2020 00:29, Jakub Kicinski wrote:
>> Other handles may take spin_locks, which will sleep on RT.
>>
>> I guess we may need to switch away from the _irqoff() variant for
>> drivers with IRQF_SHARED after all :(
>>
> Right. Unfortunately that's a large number of drivers,
> e.g. pci_request_irq() sets IRQF_SHARED in general.
IRQF_SHARED is not the problem. It only becomes a problem when the
interrupt is actually shared which is only the case with the legacy PCI
interrupt. MSI[X] is not affected at all.
> But at least for now there doesn't seem to be a better way to deal
> with the challenges imposed by forced threading and shared irqs.
We still can do the static key trick, though it's admittedly hacky.
Thanks,
tglx
