Re: [PATCH v2] alpha/PCI: Fix I/O port accessor argument order in pci_legacy_write()

[Bjorn Helgaas]

On Mon, Jul 06, 2026 at 05:54:23PM +0000, Krzysztof Wilczyński wrote:
> pci_legacy_write() in arch/alpha/kernel/pci-sysfs.c passes its arguments
> to outb(), outw() and outl() in the wrong order:
> 
>   outb(port, val);
> 
> The Alpha I/O accessors in arch/alpha/include/asm/io.h take the value
> first and the port second:
> 
>   extern void outb(u8 b, unsigned long port);
> 
> So the port number is written as data to the I/O address taken from the
> user-supplied value, and the intended write to the requested port never
> happens.
> 
> The arguments have been reversed since the file was added, and the
> function returns the access size regardless, so the caller sees success
> while the requested port is left untouched.
> 
> Fixes: 10a0ef39fbd1 ("PCI/alpha: pci sysfs resources")
> Tested-by: Magnus Lindholm <linmag7@xxxxxxxxx>
> Reviewed-by: Magnus Lindholm <linmag7@xxxxxxxxx>
> Cc: stable@xxxxxxxxxxxxxxx
> Signed-off-by: Krzysztof Wilczyński <kwilczynski@xxxxxxxxxx>

Applied to pci/sysfs for v7.3, thank you!

> ---
> Changes in v2:
>  https://lore.kernel.org/linux-pci/20260612232400.585195-1-kwilczynski@xxxxxxxxxx/
> 
>  - Collected Reviewed-by and Tested-by tags from Magnus Lindholm.
> 
>  arch/alpha/kernel/pci-sysfs.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/arch/alpha/kernel/pci-sysfs.c b/arch/alpha/kernel/pci-sysfs.c
> index 94dbc470cd6c..7050f0f7fe3d 100644
> --- a/arch/alpha/kernel/pci-sysfs.c
> +++ b/arch/alpha/kernel/pci-sysfs.c
> @@ -224,17 +224,17 @@ int pci_legacy_write(struct pci_bus *bus, loff_t port, u32 val, size_t size)
>  
>  	switch(size) {
>  	case 1:
> -		outb(port, val);
> +		outb(val, port);
>  		return 1;
>  	case 2:
>  		if (port & 1)
>  			return -EINVAL;
> -		outw(port, val);
> +		outw(val, port);
>  		return 2;
>  	case 4:
>  		if (port & 3)
>  			return -EINVAL;
> -		outl(port, val);
> +		outl(val, port);
>  		return 4;
>  	}
>  	return -EINVAL;
> -- 
> 2.55.0
>