Re: [PATCH v9 4/8] vpci: Hide extended capability when it fails to initialize

[Nicola Vetrini <nicola.vetrini@bugseng.com>]

On 2025-07-30 11:50, Jan Beulich wrote:
> On 28.07.2025 07:03, Jiqian Chen wrote:
>> +static int vpci_ext_capability_hide(
>> +    const struct pci_dev *pdev, unsigned int cap)
>> +{
>> +    const unsigned int offset = pci_find_ext_capability(pdev->sbdf, 
>> cap);
>> +    struct vpci_register *r, *prev_r;
>> +    struct vpci *vpci = pdev->vpci;
>> +    uint32_t header, pre_header;
>> +
>> +    if ( offset < PCI_CFG_SPACE_SIZE )
>> +    {
>> +        ASSERT_UNREACHABLE();
>> +        return 0;
>> +    }
>> +
>> +    spin_lock(&vpci->lock);
>> +    r = vpci_get_register(vpci, offset, 4);
>> +    if ( !r )
>> +    {
>> +        spin_unlock(&vpci->lock);
>> +        return -ENODEV;
>> +    }
>> +
>> +    header = (uint32_t)(uintptr_t)r->private;
>> +    if ( offset == PCI_CFG_SPACE_SIZE )
>> +    {
>> +        if ( PCI_EXT_CAP_NEXT(header) <= PCI_CFG_SPACE_SIZE )
>> +            r->private = (void *)(uintptr_t)0;
> 
> Eclair regards this a Misra rule 11.9 violation. Elsewhere we use (void 
> *)0,
> which I then would conclude is "fine". But I can't say why that is. 
> Cc-ing
> Bugseng for a possible explanation.
> 

Hi Jan,

I only see

0|$ git grep "(void\*)0"
xen/include/xen/types.h:#define NULL ((void*)0)

which is fine for R11.9 of course. As Andrew noted, I don't see the need 
for the use of uintptr_t either.

-- 
Nicola Vetrini, B.Sc.
Software Engineer
BUGSENG (https://bugseng.com)
LinkedIn: https://www.linkedin.com/in/nicola-vetrini-a42471253