Re: [PATCH] PCI/MSI: add iounmap in msix_capability_init()

[Guenter Roeck]

Hi,

On Sun, Jan 25, 2026 at 10:44:52PM +0800, Haoxiang Li wrote:
> In msix_capability_init(), if msix_setup_interrupts()
> fails, call iounmap() to release the memory allocated
> by msix_map_region().
> 

AI review has the following feedback:

  In __msix_setup_interrupts(), `dev` is declared with the
  `__free(free_msi_irqs)` cleanup attribute. If an error is returned,
  pci_free_msi_irqs() is automatically called.

  pci_free_msi_irqs() already unmaps dev->msix_base and sets it to NULL:

  void pci_free_msi_irqs(struct pci_dev *dev)
  {
	...
	if (dev->msix_base) {
		iounmap(dev->msix_base);
		dev->msix_base = NULL;
	}
  }

  So if msix_setup_interrupts() fails, dev->msix_base has already been
  unmapped and is NULL by the time we reach this new error path.
  Is this extra iounmap() necessary?

I checked the code, and agree.

Thanks,
Guenter

> Signed-off-by: Haoxiang Li <lihaoxiang@xxxxxxxxxxxxxxxx>
> ---
>  drivers/pci/msi/msi.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/pci/msi/msi.c b/drivers/pci/msi/msi.c
> index 34d664139f48..e010ecd9f90d 100644
> --- a/drivers/pci/msi/msi.c
> +++ b/drivers/pci/msi/msi.c
> @@ -737,7 +737,7 @@ static int msix_capability_init(struct pci_dev *dev, struct msix_entry *entries,
>  
>  	ret = msix_setup_interrupts(dev, entries, nvec, affd);
>  	if (ret)
> -		goto out_disable;
> +		goto out_unmap;
>  
>  	/* Disable INTX */
>  	pci_intx_for_msi(dev, 0);
> @@ -758,6 +758,8 @@ static int msix_capability_init(struct pci_dev *dev, struct msix_entry *entries,
>  	pcibios_free_irq(dev);
>  	return 0;
>  
> +out_unmap:
> +	iounmap(dev->msix_base);
>  out_disable:
>  	dev->msix_enabled = 0;
>  	pci_msix_clear_and_set_ctrl(dev, PCI_MSIX_FLAGS_MASKALL | PCI_MSIX_FLAGS_ENABLE, 0);
> -- 
> 2.25.1
>