On 30.07.2018 23:30, Bjorn Helgaas wrote: > [+cc Thomas, Christoph, LKML] > > On Mon, Jul 30, 2018 at 12:03:42AM +0200, Heiner Kallweit wrote: >> If we have a threaded interrupt with the handler being NULL, then >> request_threaded_irq() -> __setup_irq() will complain and bail out >> if the IRQF_ONESHOT flag isn't set. Therefore check for the handler >> being NULL and set IRQF_ONESHOT in this case. >> >> This change is needed to migrate the mei_me driver to >> pci_alloc_irq_vectors() and pci_request_irq(). >> >> Signed-off-by: Heiner Kallweit <hkallwe...@gmail.com> > > I'd like an ack from Thomas because this requirement about IRQF_ONESHOT > usage isn't mentioned in the request_threaded_irq() function doc or > Documentation/ > Sure.
That's the related comment in __setup_irq(): * The interrupt was requested with handler = NULL, so * we use the default primary handler for it. But it * does not have the oneshot flag set. In combination * with level interrupts this is deadly, because the * default primary handler just wakes the thread, then * the irq lines is reenabled, but the device still * has the level irq asserted. Rinse and repeat.... * * While this works for edge type interrupts, we play * it safe and reject unconditionally because we can't * say for sure which type this interrupt really * has. The type flags are unreliable as the * underlying chip implementation can override them. */ >> --- >> drivers/pci/irq.c | 6 +++++- >> 1 file changed, 5 insertions(+), 1 deletion(-) >> >> diff --git a/drivers/pci/irq.c b/drivers/pci/irq.c >> index 2a808e10..a1de501a 100644 >> --- a/drivers/pci/irq.c >> +++ b/drivers/pci/irq.c >> @@ -86,13 +86,17 @@ int pci_request_irq(struct pci_dev *dev, unsigned int >> nr, irq_handler_t handler, >> va_list ap; >> int ret; >> char *devname; >> + unsigned long irqflags = IRQF_SHARED; >> + >> + if (!handler) >> + irqflags |= IRQF_ONESHOT; >> >> va_start(ap, fmt); >> devname = kvasprintf(GFP_KERNEL, fmt, ap); >> va_end(ap); >> >> ret = request_threaded_irq(pci_irq_vector(dev, nr), handler, thread_fn, >> - IRQF_SHARED, devname, dev_id); >> + irqflags, devname, dev_id); >> if (ret) >> kfree(devname); >> return ret; >> -- >> 2.18.0 >> >
