[patch V2 03/36] PCI/MSI: Allocate MSI device data on first use

[Bjorn Helgaas]

On Mon, Dec 06, 2021 at 11:39:00PM +0100, Thomas Gleixner wrote:
> Allocate MSI device data on first use, i.e. when a PCI driver invokes one
> of the PCI/MSI enablement functions.
> 
> Signed-off-by: Thomas Gleixner <tglx at linutronix.de>
> Reviewed-by: Greg Kroah-Hartman <gregkh at linuxfoundation.org>
> Reviewed-by: Jason Gunthorpe <jgg at nvidia.com>

Acked-by: Bjorn Helgaas <bhelgaas at google.com>

> ---
>  drivers/pci/msi/msi.c |   20 +++++++++++++++-----
>  1 file changed, 15 insertions(+), 5 deletions(-)
> 
> --- a/drivers/pci/msi/msi.c
> +++ b/drivers/pci/msi/msi.c
> @@ -889,10 +889,12 @@ static int __pci_enable_msi_range(struct
>  /* deprecated, don't use */
>  int pci_enable_msi(struct pci_dev *dev)
>  {
> -	int rc = __pci_enable_msi_range(dev, 1, 1, NULL);
> -	if (rc < 0)
> -		return rc;
> -	return 0;
> +	int rc = msi_setup_device_data(&dev->dev);
> +
> +	if (!rc)
> +		rc = __pci_enable_msi_range(dev, 1, 1, NULL);
> +
> +	return rc < 0 ? rc : 0;
>  }
>  EXPORT_SYMBOL(pci_enable_msi);
>  
> @@ -947,7 +949,11 @@ static int __pci_enable_msix_range(struc
>  int pci_enable_msix_range(struct pci_dev *dev, struct msix_entry *entries,
>  		int minvec, int maxvec)
>  {
> -	return __pci_enable_msix_range(dev, entries, minvec, maxvec, NULL, 0);
> +	int ret = msi_setup_device_data(&dev->dev);
> +
> +	if (!ret)
> +		ret = __pci_enable_msix_range(dev, entries, minvec, maxvec, NULL, 0);
> +	return ret;
>  }
>  EXPORT_SYMBOL(pci_enable_msix_range);
>  
> @@ -974,8 +980,12 @@ int pci_alloc_irq_vectors_affinity(struc
>  				   struct irq_affinity *affd)
>  {
>  	struct irq_affinity msi_default_affd = {0};
> +	int ret = msi_setup_device_data(&dev->dev);
>  	int nvecs = -ENOSPC;
>  
> +	if (ret)
> +		return ret;
> +
>  	if (flags & PCI_IRQ_AFFINITY) {
>  		if (!affd)
>  			affd = &msi_default_affd;
>