On Thu, Mar 23, 2023 at 04:18:15PM +0000, Russell King (Oracle) wrote: > On Thu, Mar 23, 2023 at 03:23:12PM +0000, Russell King (Oracle) wrote: > > On Thu, Mar 23, 2023 at 05:00:08PM +0200, Andy Shevchenko wrote: > > > On Thu, Mar 23, 2023 at 02:49:01PM +0000, Russell King (Oracle) wrote: > > > > On Thu, Mar 23, 2023 at 04:38:29PM +0200, Andy Shevchenko wrote: > > > > > Do you modify its content on the fly? > > > > > > > > Do you want to litter code with casts to get rid of the const? > > > > > > > > > For fwnode as a basic object type we want to reduce the scope of the possible > > > > > modifications. If you don't modify and APIs you call do not require non-const > > > > > object, use const for fwnode. > > > > > > > > Let's start here. We pass this fwnode to fwnode_get_phy_mode(): > > > > > > > > include/linux/property.h:int fwnode_get_phy_mode(struct fwnode_handle *fwnode); > > > > > > > > Does fwnode_get_phy_mode() alter the contents of the fwnode? Probably > > > > not, but it doesn't take a const pointer. Therefore, to declare my > > > > fwnode as const, I'd need to cast the const-ness away before calling > > > > this. > > > > > > So, fix the fwnode_get_phy_mode(). Is it a problem? > > > > No, I refuse. That's for a different patch set. > > > > > > Then there's phylink_create(). Same problem. > > > > > > So, fix that. Is it a problem? > > > > No for the same reason. > > > > > > So NAK to this const - until such time that we have a concerted effort > > > > to making functions we call which do not modify the "fwnode" argument > > > > constify that argument. Otherwise it's just rediculously crazy to > > > > declare a variable const only to then litter the code with casts to get > > > > rid of it at every call site. > > > > > > > > Please do a bit of research before making suggestions. Thanks. > > > > > > So, MAK to your patch. You can fix that, and you know that. > > > > Sorry, I don't accept your NAK. While you have a valid point about > > these things being const, that is not the fault of this patch series, > > and is something that should be addressed separately. > > > > The lack of const-ness that has been there for quite some time is no > > reason to NAK a patch that has nothing to do with this. > > To illustrate how rediculous this is: It's not. But does it make difference? > $ git grep 'struct fwnode_handle \*.*=' > > gives 134 instances. Of those, only five are const, which means 129 > aren't. So I question - why are you singling mine out for what appears > to be special treatment. > > > Let's look at other parts of the fwnode API. > > void __iomem *fwnode_iomap(struct fwnode_handle *fwnode, int index); > > Does that modify the fwnode it was passed? It calls: > > void __iomem *(*iomap)(struct fwnode_handle *fwnode, int index); > > in struct fwnode_operations, so that would need to be made const as well. > The only implementation of that which I can find is of_fwnode_iomap() > which uses to_of_node() on that, which casts away the const-ness. So > this would be a candidate to making const. Correct. > bool fwnode_is_ancestor_of(struct fwnode_handle *ancestor, struct fwnode_handle *child); > > I'd be surprised if that modifies either of those fwnodes. It does. Now your time to be surprised. > It seems > to use fwnode_for_each_parent_node() from the child, which passes > "child" to fwnode_get_parent(), which itself is const. Therefore, it > seems there's no reason not to make "child" const. "ancestor" can > also be made const since it's only being used for pointer-compares. All getters return _different_ fwnode which is not const due to modification of the _returned_ fwnode. Do a bit of investigation, please. Thanks. > unsigned int fwnode_graph_get_endpoint_count(struct fwnode_handle *fwnode, > unsigned long flags); > > Similar story with this, although it uses > fwnode_graph_for_each_endpoint(), which seems to mean that "fwnode" > can also be const. Correct. > My point is that there are several things in the fwnode API that > should be made const but that aren't, but which should likely be > fixed before requiring const-ness of those fwnode_handle > declarations in people's code. OK. I started doing something about this as you may easily check with `git log`. Now, instead of playing a good citizen of the community you are trying to diminish the others' asks. I think the further continuation of this discussion doesn't make much sense. But thank you for your opinion. -- With Best Regards, Andy Shevchenko
