linux-kernel - Re: [patch V4 06/14] PCI/MSI: Set pci_dev::msi

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Message-ID: <20250319170848.GA1046210@bhelgaas>
Date: Wed, 19 Mar 2025 12:08:48 -0500
From: Bjorn Helgaas <helgaas@...nel.org>
To: Thomas Gleixner <tglx@...utronix.de>
Cc: LKML <linux-kernel@...r.kernel.org>, Marc Zyngier <maz@...nel.org>,
	Peter Zijlstra <peterz@...radead.org>,
	Jonathan Cameron <Jonathan.Cameron@...wei.com>,
	Nishanth Menon <nm@...com>, Dhruva Gole <d-gole@...com>,
	Tero Kristo <kristo@...nel.org>,
	Santosh Shilimkar <ssantosh@...nel.org>,
	Logan Gunthorpe <logang@...tatee.com>,
	Dave Jiang <dave.jiang@...el.com>, Jon Mason <jdmason@...zu.us>,
	Allen Hubbe <allenbh@...il.com>, ntb@...ts.linux.dev,
	Michael Kelley <mhklinux@...look.com>, Wei Liu <wei.liu@...nel.org>,
	Bjorn Helgaas <bhelgaas@...gle.com>,
	Haiyang Zhang <haiyangz@...rosoft.com>,
	linux-hyperv@...r.kernel.org, linux-pci@...r.kernel.org,
	Wei Huang <wei.huang2@....com>,
	Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>,
	"James E.J. Bottomley" <James.Bottomley@...senpartnership.com>,
	"Martin K. Petersen" <martin.petersen@...cle.com>,
	linux-scsi@...r.kernel.org,
	Jonathan Cameron <Jonathan.Cameron@...ei.com>
Subject: Re: [patch V4 06/14] PCI/MSI: Set pci_dev::msi_enabled late

On Wed, Mar 19, 2025 at 11:56:49AM +0100, Thomas Gleixner wrote:
> The comment claiming that pci_dev::msi_enabled has to be set across setup
> is a leftover from ancient code versions. Nothing in the setup code
> requires the flag to be set anymore.
> 
> Set it in the success path and remove the extra goto label.
> 
> Signed-off-by: Thomas Gleixner <tglx@...utronix.de>

Acked-by: Bjorn Helgaas <bhelgaas@...gle.com>

> ---
> V4: New patch
> ---
>  drivers/pci/msi/msi.c |   11 +++--------
>  1 file changed, 3 insertions(+), 8 deletions(-)
> 
> --- a/drivers/pci/msi/msi.c
> +++ b/drivers/pci/msi/msi.c
> @@ -359,12 +359,8 @@ static int msi_capability_init(struct pc
>  	if (nvec > 1 && !pci_msi_domain_supports(dev, MSI_FLAG_MULTI_PCI_MSI, ALLOW_LEGACY))
>  		return 1;
>  
> -	/*
> -	 * Disable MSI during setup in the hardware, but mark it enabled
> -	 * so that setup code can evaluate it.
> -	 */
> +	/* Disable MSI during setup in the hardware to erase stale state */
>  	pci_msi_set_enable(dev, 0);
> -	dev->msi_enabled = 1;
>  
>  	if (affd)
>  		masks = irq_create_affinity_masks(nvec, affd);
> @@ -372,7 +368,7 @@ static int msi_capability_init(struct pc
>  	msi_lock_descs(&dev->dev);
>  	ret = msi_setup_msi_desc(dev, nvec, masks);
>  	if (ret)
> -		goto fail;
> +		goto unlock;
>  
>  	/* All MSIs are unmasked by default; mask them all */
>  	entry = msi_first_desc(&dev->dev, MSI_DESC_ALL);
> @@ -394,6 +390,7 @@ static int msi_capability_init(struct pc
>  		goto err;
>  
>  	/* Set MSI enabled bits	*/
> +	dev->msi_enabled = 1;
>  	pci_intx_for_msi(dev, 0);
>  	pci_msi_set_enable(dev, 1);
>  
> @@ -404,8 +401,6 @@ static int msi_capability_init(struct pc
>  err:
>  	pci_msi_unmask(&desc, msi_multi_mask(&desc));
>  	pci_free_msi_irqs(dev);
> -fail:
> -	dev->msi_enabled = 0;
>  unlock:
>  	msi_unlock_descs(&dev->dev);
>  	kfree(masks);
>