Re: [PATCH RFC net-next v2 05/18] net: pse-pd: Add support for PSE device index

[Andrew Lunn]

On Thu, Oct 31, 2024 at 07:27:59AM +0100, Oleksij Rempel wrote:
> On Wed, Oct 30, 2024 at 05:53:07PM +0100, Kory Maincent wrote:
> 
> ...
> >  /**
> >   * struct pse_control - a PSE control
> > @@ -440,18 +441,22 @@ int pse_controller_register(struct pse_controller_dev *pcdev)
> >  
> >  	mutex_init(&pcdev->lock);
> >  	INIT_LIST_HEAD(&pcdev->pse_control_head);
> > +	ret = ida_alloc_max(&pse_ida, INT_MAX, GFP_KERNEL);
> 
> s/INT_MAX/U32_MAX

 * Return: The allocated ID, or %-ENOMEM if memory could not be allocated,
 * or %-ENOSPC if there are no free IDs.

static inline int ida_alloc_max(struct ida *ida, unsigned int max, gfp_t gfp)

We need to be careful here, at least theoretically. Assuming a 32 bit
system, and you pass it U32_MAX, how does it return values in the
range S32_MAX..U32_MAX when it also needs to be able to return
negative numbers as errors?

I think the correct value to pass is S32_MAX, because it will always
fit in a u32, and there is space left for negative values for errors.

But this is probably theoretical, no real system should have that many
controllers.

	Andrew