Re: MSI interrupts and disable_irq

[Manfred Spraul <manfred@colorfullife.com>]

Jeff Garzik wrote:
> I think the scenario you outline is an illustration of the approach's 
> fragility:  disable_irq() is a heavy hammer that originated with INTx, 
> and it relies on a chip-specific disable method (kernel/irq/manage.c) 
> that practically guarantees behavior will vary across MSI/INTx/etc.
I checked the code: IRQ_DISABLE is implemented in software, i.e. 
handle_level_irq() only calls handle_IRQ_event() [and then the nic irq 
handler] if IRQ_DISABLE is not set.
OTHO: The last trace looks as if nv_do_nic_poll() is interrupted by an irq.

Perhaps something corrupts dev->irq? The irq is requested with
   request_irq(np->pci_dev->irq, handler, IRQF_SHARED, dev->name, dev)
and disabled with
   disable_irq_lockdep(dev->irq);

Someone around with a MSI capable board? The forcedeth driver does
   dev->irq = pci_dev->irq
in nv_probe(), especially before pci_enable_msi().
Does pci_enable_msi() change pci_dev->irq? Then we would disable the 
wrong interrupt....

--
   Manfred
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/