On Tue, Jun 13, 2023 at 09:50:28AM +0200, Greg KH wrote:
> > DEFINE_FRERE(class_destroy, struct class *, if (!IS_ERR_OR_NULL(_T)) class_destroy(_T))
>
> Nit, as class_destroy() handles this type of check within it, it can be
> even simpler:
> DEFINE_FREE(class_destroy, struct class *, class_destroy(_T));
Note that that means there will be an unconditional call to
class_destroy() in the success path. As long as that is never a hot-path
this should be fine I suppose, but it is something Linus pointed out
earlier.
> or would that be:
> DEFINE_CLASS(class_destroy, struct class *, class_destroy(_T));
Has a slightly different syntax per the comment I did do write :-)
DEFINE_CLASS(class, struct class *,
if (!IS_ERR_OR_NULL(_T)) class_destroy(_T),
class_create(cname), const char *name)
static int __init misc_init(void)
{
struct proc_dir_entry *ret __free(remove_proc) =
proc_create_seq("misc", 0, NULL, &misc_seq_ops);
CLASS(class, c)("misc");
if (IS_ERR(c))
return PTR_ERR(c);
if (register_chrdev(MISC_MAJOR, "misc", &misc_fops))
return -EIO;
c->devnode = misc_devnode;
misc_class = no_free_ptr(c);
no_free_ptr(ret);
return 0;
}
The no_free_ptr() should work with CLASS(), but I'm not sure that's
recommended, lots of un-explored terretory here :-)
Similarly I suppose you could do something like:
DEFINE_CLASS(proc_dir, struct proc_dir_entry *,
proc_remove(_T), proc_create(pname, mode, parent, proc_ops),
const char *pname, umode_t mode, struct proc_dir_entry *parent,
const struct proc_ops *proc_ops)
EXTEND_CLASS(proc_dir, _seq, proc_create_seq(pname, mode, parent, ops, state_size, data),
const char *pname, umode_t mode, struct proc_dir_entry *parent,
const struct seq_operations *ops, unsigned int state_size, void *data)
EXTEND_CLASS(proc_dir, _seq_private, .....)
(urgh, C really needs better forwarding support)
Then you could write it something like:
static int __init misc_init(void)
{
CLASS(proc_dir_seq, ret)("misc", 0, NULL, &misc_seq_ops);
CLASS(class, c)("misc");
if (IS_ERR(c))
return PTR_ERR(c);
if (register_chrdev(MISC_MAJOR, "misc", &misc_fops))
return -EIO;
c->devnode = misc_devnode;
misc_class = no_free_ptr(c);
no_free_ptr(ret);
return 0;
}
Is what what we want?
(also, perhaps I should prefix the macro arguments with an '_', as is
you can't use 'name' as a constructor argument because the thing would
expand weird)
> I have a ton of future patches coming that does a bunch of
> class_create/destroy changes that would be made a LOT simpler with this
> patchset, and I really don't want to have to hit the same codepaths
> twice if at all possible.
>
> So what's the odds this can be reasonable enough to get into 6.5-rc1 so
> we can rely on it there?
That's one for Linus I suppose.. the only remaining issue I still have
is the no_free_*() naming. One suggestion that made sense had it called
take_*().
All we really need are the first 4 patches to land; thereafter we can
gradually start converting things.
