Re: [PATCH 00/23] add register_chrdev_ids() to char_dev.c, API

[Greg KH]

On Sat, May 21, 2011 at 02:14:23PM -0700, Greg KH wrote:
> On Fri, May 20, 2011 at 11:15:04PM -0600, Jim Cromie wrote:
> > On Thu, May 19, 2011 at 4:44 PM, Greg KH <gregkh@xxxxxxx> wrote:
> > > On Thu, May 19, 2011 at 03:33:03PM -0600, Jim Cromie wrote:
> > >> over on kernelnewbies, gregkh said:
> > >>
> > >>      The chardev stuff is a mess, I keep meaning for years to clean it
> > >>      up.  Any proposals on a sane interface for this stuff is greatly
> > >>      appreciated.
> > >>
> > >> this is a 1st step.
> > >>
> > >> register_chrdev_ids() replaces and deprecates register_chrdev_region()
> > >> and alloc_chrdev_region() with a single function that works for both
> > >> dynamic and static major numbers.
> > >>
> > >> Like alloc_chrdev_region(), 1st arg is a dev_t*, but its an in/out
> > >> parameter, and expects both major and minor to be preset, and thus the
> > >> separate minor arg is dropped.  If major == 0, a dynamic major is
> > >> reserved, saved into 1st arg, and thus available to caller afterwards.
> > >>
> > >> [PATCH 01/23] add register_chrdev_ids() to char_dev.c, API
> > >> [PATCH 02/23] reimplement alloc_chrdev_region with
> > >> [PATCH 03/23] use register_chrdev_ids to replace
> > >> [PATCH 04/23] use register_chrdev_ids in drivers/tty/
> > >> [PATCH 05/23] use register_chrdev_ids in drivers/infiniband/
> > >> [PATCH 06/23] use register_chrdev_ids in drivers/media/
> > >> [PATCH 07/23] use register_chrdev_ids in drivers/s390/
> > >> [PATCH 08/23] use register_chrdev_ids in drivers/scsi/
> > >> [PATCH 09/23] use register_chrdev_ids in drivers/staging/
> > >>
> > >> Ive held back the rest, no point in spamming.
> > >
> > > It's a nice first step, but that's the easy part, what is your 2nd
> > > through 4th one going to be?  :)
> > >
> > > I'd also like to sanatize the function namespace a bit as well, how
> > > about chrdev_register_ids() instead?
> > 
> > that seems sensible, modern.
> > also have register_chrdev(), which I presume should also be fixed.
> > 
> > > Ideally, we could drop down to a single register/unregister pair of
> > > functions, that are easy to use and understand.
> > 
> > __register_chrdev() does more stuff, mainly around cdevs, fops.
> > If fops was passed as NULL, we just do the __register_chardev_region()
> > and return early, skipping the cdev_alloc() and everything afterwards,
> > thus yielding register_chrdev_ids() behavior.
> > 
> > > Do you think you can
> > > get there with this intermediate step or do you want to step back and
> > > rethink this?
> > 
> > hmm.  If above is right, theres no need for the new api fn I added,
> > and probably should also drop the __ on both (un)?register_chardev.
> > So thats step 2 :)  Any ideas for 3 ?
> 
> Well, what do you think the end result should look like?  That will
> determine the steps needed here.

Oh, I also forgot, you need to look at the cdev_* api as well, that all
needs to be merged together with what you decide on here.

good luck,

greg k-h
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