From: Thomas Gleixner <tglx@linutronix.de>
To: Marc Zyngier <marc.zyngier@arm.com>
Cc: Ingo Molnar <mingo@kernel.org>,
"jiang.liu@linux.intel.com" <jiang.liu@linux.intel.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"hpa@zytor.com" <hpa@zytor.com>,
"linux-tip-commits@vger.kernel.org"
<linux-tip-commits@vger.kernel.org>
Subject: Re: [tip:irq/core] genirq: MSI: Fix freeing of unallocated MSI
Date: Thu, 9 Apr 2015 14:52:00 +0200 (CEST) [thread overview]
Message-ID: <alpine.DEB.2.11.1504091450570.3845@nanos> (raw)
In-Reply-To: <20150409134246.6442ede0@why.wild-wind.fr.eu.org>
On Thu, 9 Apr 2015, Marc Zyngier wrote:
> On Thu, 9 Apr 2015 13:00:23 +0100
> Ingo Molnar <mingo@kernel.org> wrote:
> >
> > Hm, so this appears to be the first time that 'irq == 0' assumptions
> > are getting into the genirq core. Is NO_IRQ dead? I realize that the
> > MSI code uses '!irq' as a flag, but still, quite a few architectures
> > define NO_IRQ so it appears to matter to them.
>
> NO_IRQ strikes back, everybody takes cover! ;-)
>
> More seriously, this seems to be two schools of thoughts on that one.
> The irqdomain subsystem seems to treat 'irq == 0' as the indication that
> 'this is not a valid IRQ', and so does MSI (as you noticed). Given that
> this code deals with MSI in conjunction with irqdomains, it felt
> natural to adopt the same convention.
>
> Also, not all the architecture are defining NO_IRQ, and it only seems
> to be used in code that is doesn't look portable across architectures.
> Either these architecture don't care about MSI, or they are happy
> enough to consider that virtual interrupt 0 is invalid in the MSI case.
>
> So I'm a bit lost on that one. I sincerely thought NO_IRQ was being
> retired (https://lwn.net/Articles/470820/). Should we introduce a
> NO_MSI_IRQ (set to zero) to take care of this case?
Nah, that'd be overkill. irq 0 is invalid for MSI in any case so we
really should stick with that convention.
Thanks,
tglx
next prev parent reply other threads:[~2015-04-09 12:51 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-01-26 19:10 [PATCH] genirq: MSI: Fix freeing of unallocated MSI Marc Zyngier
2015-01-27 5:33 ` Jiang Liu
2015-04-08 21:30 ` [tip:irq/core] " tip-bot for Marc Zyngier
2015-04-09 12:00 ` Ingo Molnar
2015-04-09 12:42 ` Marc Zyngier
2015-04-09 12:52 ` Thomas Gleixner [this message]
2015-04-09 14:49 ` Ingo Molnar
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