Re: [Xen-devel] [PATCH 2/2] xen: events: free irqs in error condition

["Shah, Amit" <aams@xxxxxxxxx>]

On Di, 2018-02-27 at 08:14 +0000, Roger Pau Monné wrote:
> On Mon, Feb 26, 2018 at 06:57:03PM +0000, Shah, Amit wrote:
> > 
> > 
> > On Mo, 2018-02-26 at 18:14 +0000, Roger Pau Monné wrote:
> > > 
> > > On Mon, Feb 26, 2018 at 05:36:35PM +0000, Amit Shah wrote:
> > > > 
> > > > 
> > > > In case of errors in irq setup for MSI, free up the allocated
> > > > irqs.
> > > > 
> > > > Fixes: 4892c9b4ada9f9 ("xen: add support for MSI message
> > > > groups")
> > > > Reported-by: Hooman Mirhadi <mirhadih@xxxxxxxxxx>
> > > > CC: <stable@xxxxxxxxxxxxxxx>
> > > > CC: Roger Pau Monné <roger.pau@xxxxxxxxxx>
> > > > CC: David Vrabel <david.vrabel@xxxxxxxxxx>
> > > > CC: Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>
> > > > CC: Eduardo Valentin <eduval@xxxxxxxxxx>
> > > > CC: Juergen Gross <jgross@xxxxxxxx>
> > > > CC: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
> > > > CC: "K. Y. Srinivasan" <kys@xxxxxxxxxxxxx>
> > > > CC: Liu Shuo <shuo.a.liu@xxxxxxxxx>
> > > > CC: Anoob Soman <anoob.soman@xxxxxxxxxx>
> > > > Signed-off-by: Amit Shah <aams@xxxxxxxxxx>
> > > > ---
> > > >  drivers/xen/events/events_base.c | 1 +
> > > >  1 file changed, 1 insertion(+)
> > > > 
> > > > diff --git a/drivers/xen/events/events_base.c
> > > > b/drivers/xen/events/events_base.c
> > > > index b6b8b29..96aa575 100644
> > > > --- a/drivers/xen/events/events_base.c
> > > > +++ b/drivers/xen/events/events_base.c
> > > > @@ -758,6 +758,7 @@ int xen_bind_pirq_msi_to_irq(struct pci_dev
> > > > *dev, struct msi_desc *msidesc,
> > > >  error_irq:
> > > >         for (; i >= 0; i--)
> > > >                 __unbind_from_irq(irq + i);
> > > > +       xen_free_irq(irq);
> > > Hm, xen_free_irq calls irq_free_desc, which is
> > > irq_free_descs(irq,
> > > 1),
> > Er...  right.
> > 
> > > 
> > > I think you will have to introduce a new free function:
> > > 
> > > xen_free_irqs(unsigned irq, unsigned int nr)
> > > 
> > > That calls irq_free_descs(irq, nr)
> > Actually, xen_free_irq() is already done in __unbind_from_irq(), so
> > this patch is actually wrong and not needed.
> You still need to free unbound IRQs, AFAICT you could fix the issue
> with a single patch, like:
> 
> while (nvec--) {
>       if (nvec >= i)
>               xen_free_irq(irq + i);
>       else
>               __unbind_from_irq(irq + i);
> }

Agreed.

However, since these are two different things, I'd still like to
separate out into two patches, and two paths so it's easier to see
what's being done.

Sending v2 in a bit.

    Amit


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