Re: [PATCH] counter: interrupt-cnt: Protect enable/disable OPs with mutex

[William Breathitt Gray <wbg@kernel.org>]

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On Fri, May 02, 2025 at 09:24:20AM +0000, Sverdlin, Alexander wrote:
> Dear maintainers,
> 
> On Mon, 2025-03-31 at 18:36 +0200, A. Sverdlin wrote:
> > From: Alexander Sverdlin <alexander.sverdlin@siemens.com>
> >
> > Enable/disable seems to be racy on SMP, consider the following scenario:
> >
> > CPU0					CPU1
> >
> > interrupt_cnt_enable_write(true)
> > {
> > 	if (priv->enabled == enable)
> > 		return 0;
> >
> > 	if (enable) {
> > 		priv->enabled = true;
> > 					interrupt_cnt_enable_write(false)
> > 					{
> > 						if (priv->enabled == enable)
> > 							return 0;
> >
> > 						if (enable) {
> > 							priv->enabled = true;
> > 							enable_irq(priv->irq);
> > 						} else {
> > 							disable_irq(priv->irq)
> > 							priv->enabled = false;
> > 						}
> > 		enable_irq(priv->irq);
> > 	} else {
> > 		disable_irq(priv->irq);
> > 		priv->enabled = false;
> > 	}
> >
> > The above would result in priv->enabled == false, but IRQ left enabled.
> > Protect both write (above race) and read (to propagate the value on SMP)
> > callbacks with a mutex.
> >
> > Signed-off-by: Alexander Sverdlin <alexander.sverdlin@siemens.com>
> 
> I've noticed that the patch has been marked as "Changes Requested" in
> the patchwork, could it be a mistake? Because I never received any
> change request.

Hi Alexander,

I can't comment on the patchwork status because I don't use that
service, but I apologize nonetheless for the delay in responding to your
patch submission. I'm hoping for an Ack from Oleksij, but this is a
pretty straight-forward fix that I'll be happy to pick it up regardless.

Would you provide a Fixes line so the stable trees can pick this up for
the necessary kernel versions?

Thanks,

William Breathitt Gray

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