[PATCH 11/19] regmap: avoid undefined return from regmap_read_debugfs

On Sat, Jan 26, 2013 at 05:49:29PM +0800, Mark Brown wrote:

Oh, ffs.  This is a false positive from the compiler - there is no case
where it can actually do this as we will bail out before the walk if the
list is empty so we'll always take at least one trip through our
list_for_each_entry() and either return or set ret.  It should be smart
enough to work out that the list_empty() means list_for_each_entry()
will iterate over at least one entry or more conservative in what it
warns about.

Why not code the function in a way that avoids the problem altogether?

	/*
	 * This should never happen; we return above if we fail to
	 * allocate and we should never be in this code if there are
	 * no registers at all.
	 */
-	if (list_empty(&map->debugfs_off_cache)) {
-		WARN_ON(list_empty(&map->debugfs_off_cache));
-		return base;
-	}
+	WARN_ON(list_empty(&map->debugfs_off_cache));
+	ret = base;

	/* Find the relevant block */
	list_for_each_entry(c, &map->debugfs_off_cache, list) {
		if (from >= c->min && from <= c->max) {
			*pos = c->min;
			return c->base_reg;
		}

		*pos = c->min;
		ret = c->base_reg;
	}

	return ret;