linux-kernel - Re: [PATCH 2/2] xen: events: free irqs in error condition

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Message-ID: <1519746360.4965.21.camel@amazon.com>
Date:   Tue, 27 Feb 2018 15:46:00 +0000
From:   "Shah, Amit" <aams@...zon.de>
To:     "roger.pau@...rix.com" <roger.pau@...rix.com>
CC:     "boris.ostrovsky@...cle.com" <boris.ostrovsky@...cle.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "tglx@...utronix.de" <tglx@...utronix.de>,
        "kys@...rosoft.com" <kys@...rosoft.com>,
        "jgross@...e.com" <jgross@...e.com>,
        "stable@...r.kernel.org" <stable@...r.kernel.org>,
        "shuo.a.liu@...el.com" <shuo.a.liu@...el.com>,
        "anoob.soman@...rix.com" <anoob.soman@...rix.com>,
        "Valentin, Eduardo" <eduval@...126.com>,
        "xen-devel@...ts.xenproject.org" <xen-devel@...ts.xenproject.org>
Subject: Re: [PATCH 2/2] xen: events: free irqs in error condition



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@...zon.com>
> > > > CC: <stable@...r.kernel.org>
> > > > CC: Roger Pau Monné <roger.pau@...rix.com>
> > > > CC: David Vrabel <david.vrabel@...rix.com>
> > > > CC: Boris Ostrovsky <boris.ostrovsky@...cle.com>
> > > > CC: Eduardo Valentin <eduval@...zon.com>
> > > > CC: Juergen Gross <jgross@...e.com>
> > > > CC: Thomas Gleixner <tglx@...utronix.de>
> > > > CC: "K. Y. Srinivasan" <kys@...rosoft.com>
> > > > CC: Liu Shuo <shuo.a.liu@...el.com>
> > > > CC: Anoob Soman <anoob.soman@...rix.com>
> > > > Signed-off-by: Amit Shah <aams@...zon.com>
> > > > ---
> > > >  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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