RE: [PATCH net, 1/2] net: mana: Fix hint value before free irq

[Haiyang Zhang <haiyangz@microsoft.com>]

> -----Original Message-----
> From: Michael Kelley (LINUX) <mikelley@microsoft.com>
> Sent: Sunday, January 29, 2023 9:26 AM
> To: Haiyang Zhang <haiyangz@microsoft.com>; linux-hyperv@vger.kernel.org;
> netdev@vger.kernel.org
> Cc: Haiyang Zhang <haiyangz@microsoft.com>; Dexuan Cui
> <decui@microsoft.com>; KY Srinivasan <kys@microsoft.com>; Paul Rosswurm
> <paulros@microsoft.com>; olaf@aepfle.de; vkuznets@redhat.com;
> davem@davemloft.net; linux-kernel@vger.kernel.org; stable@vger.kernel.org
> Subject: RE: [PATCH net, 1/2] net: mana: Fix hint value before free irq
> 
> From: LKML haiyangz <lkmlhyz@microsoft.com> On Behalf Of Haiyang Zhang
> Sent: Thursday, January 26, 2023 1:05 PM
> >
> > Need to clear affinity_hint before free_irq(), otherwise there is a
> > one-time warning and stack trace during module unloading.
> >
> > To fix this bug, set affinity_hint to NULL before free as required.
> >
> > Cc: stable@vger.kernel.org
> > Fixes: 71fa6887eeca ("net: mana: Assign interrupts to CPUs based on NUMA
> nodes")
> > Signed-off-by: Haiyang Zhang <haiyangz@microsoft.com>
> > ---
> >  drivers/net/ethernet/microsoft/mana/gdma_main.c | 5 +++++
> >  1 file changed, 5 insertions(+)
> >
> > diff --git a/drivers/net/ethernet/microsoft/mana/gdma_main.c
> > b/drivers/net/ethernet/microsoft/mana/gdma_main.c
> > index b144f2237748..3bae9d4c1f08 100644
> > --- a/drivers/net/ethernet/microsoft/mana/gdma_main.c
> > +++ b/drivers/net/ethernet/microsoft/mana/gdma_main.c
> > @@ -1297,6 +1297,8 @@ static int mana_gd_setup_irqs(struct pci_dev
> *pdev)
> >  	for (j = i - 1; j >= 0; j--) {
> >  		irq = pci_irq_vector(pdev, j);
> >  		gic = &gc->irq_contexts[j];
> > +
> > +		irq_update_affinity_hint(irq, NULL);
> >  		free_irq(irq, gic);
> >  	}
> >
> > @@ -1324,6 +1326,9 @@ static void mana_gd_remove_irqs(struct pci_dev
> *pdev)
> >  			continue;
> >
> >  		gic = &gc->irq_contexts[i];
> > +
> > +		/* Need to clear the hint before free_irq */
> > +		irq_update_affinity_hint(irq, NULL);
> >  		free_irq(irq, gic);
> >  	}
> >
> > --
> > 2.25.1
> 
> I think this patch should be folded into the second patch of this series.  While
> this patch makes the warning go away, it doesn't really solve any problems by
> itself.  It just papers over the warning.  My first reaction on seeing this patch
> is that the warning exists because the memory for the mask likely had
> been incorrectly managed, which is exactly the case.  Since this patch doesn't
> really fix a problem on its own, I'd say merge it into the second patch.
> 
> That's just my $.02.  If you really want to keep it separate, that's not a
> blocker for me.

Will do.

Thanks,
- Haiyang