On Thu, 31 Oct 2024 22:28:29 +0100 Andrew Lunn <andrew@xxxxxxx> wrote: > 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. Indeed you are right we might have issue between S32_MAX and U32_MAX if we want to return errors. Small question, is S32_MAX better than INT_MAX? Is there a point to limit it to 32 bits? Regards, -- Köry Maincent, Bootlin Embedded Linux and kernel engineering https://bootlin.com
