Re: [PATCH 3/3] genirq/irqdomain: Detect type race in irq_create_fwspec_mapping()

On 12/09/2019 10:44, Sverdlin, Alexander (Nokia - DE/Ulm) wrote:

From: Alexander Sverdlin alexander.sverdlin@nokia.com

irq_create_fwspec_mapping() can race with itself during IRQ trigger type configuration. Possible scenarios include:

• Mapping exists, two irq_create_fwspec_mapping() running in parallel do not detect type mismatch, IRQ remains configured with one of the different trigger types randomly
• Second call to irq_create_fwspec_mapping() sees existing mapping just created by first call, but earlier irqd_set_trigger_type() call races with later irqd_set_trigger_type() => totally undetected, IRQ type is being set randomly to either one or another type

Is that an actual thing? Frankly, the scenario you're describing here seems to carry the hallmarks of a completely broken system. Can you point at a system supported in mainline that would behave as such?

Thanks,

M.