On Mon, 17 Feb 2014, Stanislaw Gruszka wrote:
> There is threadirqs kenel boot option which allow to force interrupt
> routines to be performed as thread.
>
> USB irq routines use spin_lock(*hci->lock) variant without disabling
> interrupts, what is perfectly fine, but that can cause deadlock when
> forced thread irqs are used. Deadlock scenario is quite reproducible for
> me, as I can not boot system with threadirqs option, when some USB
> device is connected. Patch marks USB irq routines with IRQF_NO_THREAD
> to prevent forced threading.
>
> Signed-off-by: Stanislaw Gruszka <sgruszka@xxxxxxxxxx>
NACK.
This is the wrong approach and will break RT. See the discussion about
EHCI.
Thanks,
tglx
> ---
> drivers/usb/core/hcd-pci.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/usb/core/hcd-pci.c b/drivers/usb/core/hcd-pci.c
> index d59d993..b4fa1a5 100644
> --- a/drivers/usb/core/hcd-pci.c
> +++ b/drivers/usb/core/hcd-pci.c
> @@ -264,7 +264,7 @@ int usb_hcd_pci_probe(struct pci_dev *dev, const struct pci_device_id *id)
> down_write(&companions_rwsem);
> dev_set_drvdata(&dev->dev, hcd);
> for_each_companion(dev, hcd, ehci_pre_add);
> - retval = usb_add_hcd(hcd, hcd_irq, IRQF_SHARED);
> + retval = usb_add_hcd(hcd, hcd_irq, IRQF_SHARED | IRQF_NO_THREAD);
> if (retval != 0)
> dev_set_drvdata(&dev->dev, NULL);
> for_each_companion(dev, hcd, ehci_post_add);
> @@ -272,7 +272,7 @@ int usb_hcd_pci_probe(struct pci_dev *dev, const struct pci_device_id *id)
> } else {
> down_read(&companions_rwsem);
> dev_set_drvdata(&dev->dev, hcd);
> - retval = usb_add_hcd(hcd, hcd_irq, IRQF_SHARED);
> + retval = usb_add_hcd(hcd, hcd_irq, IRQF_SHARED | IRQF_NO_THREAD);
> if (retval != 0)
> dev_set_drvdata(&dev->dev, NULL);
> else
> --
> 1.7.11.7
>
>
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