Re: [PATCH v2 1/3] lib/igt_sriov_device: Add helper to get SR-IOV function name

["Bernatowicz, Marcin" <marcin.bernatowicz@linux.intel.com>]

On 9/7/2026 2:46 PM, Lukasz Laguna wrote:
> Introduce a helper to format SR-IOV function names. It returns "PF" for
> physical function and "VF%u" for virtual functions.
>
> Signed-off-by: Lukasz Laguna <lukasz.laguna@intel.com>
> ---
>   lib/igt_sriov_device.c | 23 +++++++++++++++++++++++
>   lib/igt_sriov_device.h |  1 +
>   2 files changed, 24 insertions(+)
>
> diff --git a/lib/igt_sriov_device.c b/lib/igt_sriov_device.c
> index 6c9fbdf70..392c80346 100644
> --- a/lib/igt_sriov_device.c
> +++ b/lib/igt_sriov_device.c
> @@ -61,6 +61,29 @@ const char *igt_sriov_func_str(unsigned int vf_num)
>   	return buf;
>   }
>   
> +/**
> + * igt_sriov_function_name - Get SR-IOV function name
> + * @vf_num: VF number (1-based to identify single VF) or 0 for PF
> + * @buf: buffer
> + * @size: size of the buffer
> + *
> + * It formats the function name as "PF" when @vf_num is 0, or as "VF%u"
> + * when @vf_num is greater than 0.
> + *
> + * Return: formatted function name.
> + */
> +const char *igt_sriov_function_name(unsigned int vf_num, char *buf, size_t size)
> +{
> +	int n;
> +
> +	n = vf_num ? snprintf(buf, size, "VF%u", vf_num) :
> +		     snprintf(buf, size, "PF");
> +
> +	igt_assert(n >= 0 && (size_t)n < size);
> +
> +	return buf;
> +}
> +

NIT: We already have igt_sriov_func_str(), although it relies on a 
thread-local buffer.

Would it make sense to factor the formatting into a helper,

with lower- and uppercase wrappers, for example:

static const char *sriov_function_name(unsigned int vf_num, bool uppercase,
                        char *buf, size_t size)
{
     int ret;

     igt_assert(buf && size);

     if (vf_num)
         ret = snprintf(buf, size, uppercase ? "VF%u" : "vf%u", vf_num);
     else
         ret = snprintf(buf, size, "%s", uppercase ? "PF" : "pf");

     igt_assert(ret >= 0 && (size_t)ret < size);

     return buf;
}

const char *igt_sriov_function_name_lower(unsigned int vf_num,
                       char *buf, size_t size)
{
     return sriov_function_name(vf_num, false, buf, size);
}

const char *igt_sriov_function_name_upper(unsigned int vf_num,
                       char *buf, size_t size)
{
     return sriov_function_name(vf_num, true, buf, size);
}

igt_sriov_func_str() could initially remain as a compatibility wrapper

around the lowercase helper, with migrating its callers left for a 
follow-up.

--

marcin

>   static bool __pf_attr_get_u32(int pf, const char *attr, uint32_t *value)
>   {
>   	int sysfs;
> diff --git a/lib/igt_sriov_device.h b/lib/igt_sriov_device.h
> index 4e4ba230a..a969d4172 100644
> --- a/lib/igt_sriov_device.h
> +++ b/lib/igt_sriov_device.h
> @@ -36,6 +36,7 @@ bool igt_sriov_device_reset_exists(int pf, unsigned int vf_num);
>   bool igt_sriov_device_reset(int pf, unsigned int vf_num);
>   bool intel_is_vf_device(int device);
>   const char *igt_sriov_func_str(unsigned int vf_num);
> +const char *igt_sriov_function_name(unsigned int vf_num, char *buf, size_t size);
>   typedef void (*igt_sriov_exit_cleanup_fn)(int pf, int sig, void *user_data);
>   void igt_sriov_install_exit_handler(int pf,
>   				    igt_sriov_exit_cleanup_fn cleanup_fn,