On Wed, 20 May 2015, Jiang Liu wrote:

On 2015/5/16 5:02, Thomas Gleixner wrote:

quoted

This is a bit odd. With your proposed change we'll have:

     alloc_legacy_irq()

     msi[x]_enable()
	free_legacy_irq()

     msi[x]_disable()
	alloc_legacy_irq()

Hi Thomas,
	It's for safety. I'm not sure whether the device driver will
make use of legacy IRQ after calling msi[x]_disable(). I have concerns
about following pattern in PCI device drivers:
---------------------------------------------------
if (enable_msi() == SUCCESS) {
	if (allocate_resource_for_msi() == SUCCESS)
		return;
	disable_msi();
}
use_legacy_irq()

Fair enough.

     tglx