On Mon, Aug 26, 2024 at 05:18:57PM +0530, Riyan Dhiman wrote:

quoted

Of course, there is a place for unsigned types in C but it's so subtle and
complicated to explain.  I think people wish that there was a way to make C
safer when there really isn't.  There is no easy answer like just declare
everything as u32.  It's a false hope.

There is a function in the vme_user driver (vme.c:L715)

unsigned int vme_master_rmw(struct vme_resource *resource, unsigned int
mask,
   unsigned int compare, unsigned int swap, loff_t offset)
{
struct vme_bridge *bridge = find_bridge(resource);
struct vme_master_resource *image;

if (!bridge->master_rmw) {
dev_warn(bridge->parent, "Writing to resource not supported\n");
return -EINVAL;
}

if (resource->type != VME_MASTER) {
dev_err(bridge->parent, "Not a master resource\n");
return -EINVAL;
}

image = list_entry(resource->entry, struct vme_master_resource, list);

return bridge->master_rmw(image, mask, compare, swap, offset);
}
EXPORT_SYMBOL(vme_master_rmw);

It is declared as unsigned everywhere but returns negative error codes.
This is an issue,
 right? How should it be fixed? Do we need to change all the function
declarations to int,
or just in this function, since bridge->master_rmw returns an unsigned int?

Easy answer: Just delete vme_master_rmw() because nothing uses it.

Complicated answer: So long as the caller is saving it to int then it will work
okay.  If it saves it to any other type then it will cause problems.

regards,
dan carpenter