Messages in this thread | | | Date | Mon, 3 Jul 2023 15:38:42 +0200 | From | Greg Kroah-Hartman <> | Subject | Re: [PATCH 2/2] include/uapi pps.h: drop not needed PPS_MAX_SOURCES define |
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On Fri, Jun 30, 2023 at 03:29:50PM +0200, Rodolfo Giometti wrote: > On 30/06/23 14:53, Greg Kroah-Hartman wrote: > > On Fri, Jun 30, 2023 at 09:50:33AM +0200, Rodolfo Giometti wrote: > > > On 30/06/23 09:31, Greg Kroah-Hartman wrote: > > > > On Fri, Jun 30, 2023 at 09:18:26AM +0200, Rodolfo Giometti wrote: > > > > > Userspace PPS clients should not known about how many PPS sources can > > > > > be defined within the system (nor the rfc2783 say so), so we can > > > > > safely drop this define since is not used anymore in the kernel too. > > > > > > > > > > Signed-off-by: Rodolfo Giometti <giometti@enneenne.com> > > > > > --- > > > > > drivers/pps/pps.c | 6 +++--- > > > > > include/uapi/linux/pps.h | 1 - > > > > > 2 files changed, 3 insertions(+), 4 deletions(-) > > > > > > > > > > diff --git a/drivers/pps/pps.c b/drivers/pps/pps.c > > > > > index 5d19baae6a38..1a6131608036 100644 > > > > > --- a/drivers/pps/pps.c > > > > > +++ b/drivers/pps/pps.c > > > > > @@ -354,7 +354,7 @@ int pps_register_cdev(struct pps_device *pps) > > > > > * Get new ID for the new PPS source. After idr_alloc() calling > > > > > * the new source will be freely available into the kernel. > > > > > */ > > > > > - err = idr_alloc(&pps_idr, pps, 0, PPS_MAX_SOURCES, GFP_KERNEL); > > > > > + err = idr_alloc(&pps_idr, pps, 0, MINORMASK, GFP_KERNEL); > > > > > if (err < 0) { > > > > > if (err == -ENOSPC) { > > > > > pr_err("%s: too many PPS sources in the system\n", > > > > > @@ -449,7 +449,7 @@ EXPORT_SYMBOL(pps_lookup_dev); > > > > > static void __exit pps_exit(void) > > > > > { > > > > > class_destroy(pps_class); > > > > > - unregister_chrdev_region(pps_devt, PPS_MAX_SOURCES); > > > > > + unregister_chrdev_region(pps_devt, MINORMASK); > > > > > } > > > > > static int __init pps_init(void) > > > > > @@ -463,7 +463,7 @@ static int __init pps_init(void) > > > > > } > > > > > pps_class->dev_groups = pps_groups; > > > > > - err = alloc_chrdev_region(&pps_devt, 0, PPS_MAX_SOURCES, "pps"); > > > > > + err = alloc_chrdev_region(&pps_devt, 0, MINORMASK, "pps"); > > > > > if (err < 0) { > > > > > pr_err("failed to allocate char device region\n"); > > > > > goto remove_class; > > > > > diff --git a/include/uapi/linux/pps.h b/include/uapi/linux/pps.h > > > > > index 90f2e86020ba..8a4096f18af1 100644 > > > > > --- a/include/uapi/linux/pps.h > > > > > +++ b/include/uapi/linux/pps.h > > > > > @@ -26,7 +26,6 @@ > > > > > #include <linux/types.h> > > > > > #define PPS_VERSION "5.3.6" > > > > > -#define PPS_MAX_SOURCES MINORMASK > > > > > > > > Why change this in patch 1, and then delete this here? > > > > > > > > That makes no sense. > > > > > > I did it in two steps to be clear that the first step is about a better > > > redefinition of the PPS_MAX_SOURCES define, while the second step is about > > > the fact it's now that define is useless. > > > > Better to just convert everything in patch one, and then in patch 2 > > delete the .h #define. That way, when userspace breaks, you can revert > > just the last patch :) > > I'm puzzled since I did as you say... patch 1/2 increases PPS_MAX_SOURCES > value while patch 2/2 drops PPS_MAX_SOURCES define.
Ah, I thought patch 1/2 renamed it.
But why increase it if you are removing it?
> > > > And if this is exported to userspace, removing it should break things, > > > > right? If not, why was it there in the first place? > > > > > > In reality such define is not stated within the PPS RFC2783, so userspace > > > programs whose relies on such define are broken. > > > > RFC's do not document Linux kernel apis. > > It's true, but well written PPS clients should relay only on PPS API which > in turn doesn't states that define. :P
Are you sure? Have you audited the clients? if so, please document that in the changelog text.
> > So if any userspace code breaks, you have to put this back, sorry. > > If you think that patch 2 is not good, no problem, just drop it, but please > just consider applying patch 1, since increasing PPS_MAX_SOURCES value is > good.
You can't change a uapi value either without breaking things :(
thanks,
greg k-h
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