Re: pci-ftpci100: race condition in masking/unmasking interrupts

[Linus Walleij]

On Wed, Aug 18, 2021 at 1:47 PM Pali Rohár <pali@xxxxxxxxxx> wrote:

> I do not see any entry in MAINTAINERS file for pci-ftpci100.c driver, so
> I'm not sure to whom should I address this issue...

It's me.

> During pci-aardvark review, Marc pointed one issue which is currently
> available also in pci-ftpci100.c driver.
>
> When masking or unmasking interrupts there is read-modify-write sequence
> for FARADAY_PCI_CTRL2 register without any locking and is not atomic:
>
> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/pci/controller/pci-ftpci100.c?h=v5.13#n270
>
> So there is race condition when masking/unmasking more interrupts at the
> same time.

I thought those operations were called in atomic context.
How did you fix it?

Yours,
Linus Walleij