linux-kernel - Re: [Patch Part2 v4 20/31] PCI/MSI: Kill redundant calling for irq_set_msi

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Date:	Wed, 5 Nov 2014 15:45:04 -0700
From:	Bjorn Helgaas <bhelgaas@...gle.com>
To:	Jiang Liu <jiang.liu@...ux.intel.com>
Cc:	Benjamin Herrenschmidt <benh@...nel.crashing.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
	"H. Peter Anvin" <hpa@...or.com>,
	"Rafael J. Wysocki" <rjw@...ysocki.net>,
	Randy Dunlap <rdunlap@...radead.org>,
	Yinghai Lu <yinghai@...nel.org>,
	Borislav Petkov <bp@...en8.de>,
	Grant Likely <grant.likely@...aro.org>,
	Marc Zyngier <marc.zyngier@....com>,
	Yingjoe Chen <yingjoe.chen@...iatek.com>,
	Matthias Brugger <matthias.bgg@...il.com>,
	Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Tony Luck <tony.luck@...el.com>,
	Joerg Roedel <joro@...tes.org>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	x86@...nel.org, linux-kernel@...r.kernel.org,
	linux-pci@...r.kernel.org, linux-acpi@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org
Subject: Re: [Patch Part2 v4 20/31] PCI/MSI: Kill redundant calling for
 irq_set_msi_desc() for MSIx interrupts

On Tue, Nov 04, 2014 at 08:01:54PM +0800, Jiang Liu wrote:
> It's arch_setup_msi_irq()/arch_setup_msi_irqs()'s responsibility to call
> irq_set_msi_desc() to associate IRQ descriptors and MSI descriptors,
> so kill the redundant call of irq_set_msi_desc() for MSIx interrupts
> in PCI MSI core.

"MSI-X" in English text, "msix" in code.

The default arch_setup_msi_irq() in drivers/pci/msi.c doesn't call
irq_set_msi_desc().  Does it happen somewhere inside chip->setup_irq()?

I don't know how to verify that there are calls in all the places needed.
That makes me wonder if the factoring is wrong -- maybe irq_set_msi_desc()
could be done in some common place.

> Signed-off-by: Jiang Liu <jiang.liu@...ux.intel.com>
> ---
>  drivers/pci/msi.c |    1 -
>  1 file changed, 1 deletion(-)
> 
> diff --git a/drivers/pci/msi.c b/drivers/pci/msi.c
> index afe974600c7d..da181c59394b 100644
> --- a/drivers/pci/msi.c
> +++ b/drivers/pci/msi.c
> @@ -685,7 +685,6 @@ static void msix_program_entries(struct pci_dev *dev,
>  						PCI_MSIX_ENTRY_VECTOR_CTRL;
>  
>  		entries[i].vector = entry->irq;
> -		irq_set_msi_desc(entry->irq, entry);
>  		entry->masked = readl(entry->mask_base + offset);
>  		msix_mask_irq(entry, 1);
>  		i++;
> -- 
> 1.7.10.4
> 
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