Re: [PATCH v2 2/6] sysctl: add unsigned int limit constants

[Alexey Gladkov]

On Thu, Sep 24, 2026 at 03:29:35PM +0200, Joel Granados wrote:
> On Mon, Sep 21, 2026 at 12:54:49PM +0200, Alexey Gladkov wrote:
> > Some sysctl handlers use unsigned int storage for their limit arguments.
> > In particular, proc_dou8vec_minmax() expects extra1 and extra2 to point
> > to unsigned int values even though the controlled data is an u8.
> 
> This one reads like a fix as opposed to part of your series. Is it
> strictly needed for what you are proposing here?

Yeah, it turned out a bit wonky. Sorry.

What I was trying to say is that we don't have shared constants for
`unsigned int`. It doesn't matter right now since the size is the same,
but if we check the type at compile time, then it becomes important.

> > 
> > Provide shared unsigned int constants so typed sysctl descriptors can
> > pass correctly typed min and max pointers without casting the existing
> > int constants.
> > 
> > Signed-off-by: Alexey Gladkov <legion@xxxxxxxxxx>
> > ---
> >  include/linux/sysctl.h | 7 +++++++
> >  kernel/sysctl.c        | 3 +++
> >  2 files changed, 10 insertions(+)
> > 
> > diff --git a/include/linux/sysctl.h b/include/linux/sysctl.h
> > index e5d7226ab6f5..7139a4c72736 100644
> > --- a/include/linux/sysctl.h
> > +++ b/include/linux/sysctl.h
> > @@ -59,6 +59,12 @@ extern const int sysctl_vals[];
> >  #define SYSCTL_LONG_ONE		((void *)&sysctl_long_vals[1])
> >  #define SYSCTL_LONG_MAX		((void *)&sysctl_long_vals[2])
> >  
> > +#define SYSCTL_UINT_ZERO	((unsigned int *)&sysctl_uint_vals[0])
> > +#define SYSCTL_UINT_ONE		((unsigned int *)&sysctl_uint_vals[1])
> > +#define SYSCTL_UINT_TWO		((unsigned int *)&sysctl_uint_vals[2])
> > +#define SYSCTL_UINT_THREE	((unsigned int *)&sysctl_uint_vals[3])
> > +#define SYSCTL_UINT_FOUR	((unsigned int *)&sysctl_uint_vals[4])
> 
> I would really like to avoid that. Its one of the things that should
> probably go away in the future [1], [2], [3], [4]
> 
> [1] https://lore.kernel.org/all/875xyczpzm.fsf@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxx/
> [2] https://lore.kernel.org/all/tencent_C5E6023F97E7CC2A046AAEA09BC9ACF43907@xxxxxx/
> [3] https://lore.kernel.org/all/cover.1739115369.git.wen.yang@xxxxxxxxx/
> [4] https://lore.kernel.org/all/qnrzl4tjlgw5rzlvxavr3pt7fhkslnm4dd62q7uqzb3mfoa2jg@fuayx77rfcs6/

I don't mind removing them and using constants in the relevant source
files. I added these constants because they are used in the net subsystem.

As example:

https://web.git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/net/mptcp/ctrl.c#n294
https://web.git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/ipc/ipc_sysctl.c#n110

> 
> > +
> >  /*
> >   *
> >   * "dir" originates from read_iter (dir = 0) or write_iter (dir = 1)
> > @@ -73,6 +79,7 @@ extern const int sysctl_vals[];
> >  #define SYSCTL_KERN_TO_USER(dir) (!dir)
> >  
> >  extern const unsigned long sysctl_long_vals[];
> > +extern const unsigned int sysctl_uint_vals[];
> >  
> >  typedef int proc_handler(const struct ctl_table *ctl, int dir, void *buf,
> >  			 size_t *lenp, loff_t *ppos);
> > diff --git a/kernel/sysctl.c b/kernel/sysctl.c
> > index f7b75985d542..54edaa2fd5d5 100644
> > --- a/kernel/sysctl.c
> > +++ b/kernel/sysctl.c
> > @@ -29,6 +29,9 @@ EXPORT_SYMBOL(sysctl_vals);
> >  const unsigned long sysctl_long_vals[] = { 0, 1, LONG_MAX };
> >  EXPORT_SYMBOL_GPL(sysctl_long_vals);
> >  
> > +const unsigned int sysctl_uint_vals[] = { 0, 1, 2, 3, 4 };
> > +EXPORT_SYMBOL_GPL(sysctl_uint_vals);
> > +
> >  #if defined(CONFIG_SYSCTL)
> >  
> >  /* Constants used for minimum and maximum */
> > -- 
> > 2.55.0
> > 



-- 
Rgrds, legion

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