Re: [PATCH v2] sysctl: treewide: constify the ctl_table argument of proc_handlers

From: Thomas Weißschuh
Date: Thu Jun 20 2024 - 10:35:05 EST


On 2024-06-20 12:34:51+0000, Joel Granados wrote:
> On Wed, Jun 19, 2024 at 12:09:00PM +0200, Thomas Weißschuh wrote:
> > Adapt the proc_hander function signature to make it clear that handlers
> > are not supposed to modify their ctl_table argument.
> >
> > This is also a prerequisite to moving the static ctl_table structs into
> > read-only data.
> >
> > The patch was mostly generated by coccinelle with the following script:
> >
> > @@
> > identifier func, ctl, write, buffer, lenp, ppos;
> > @@
> >
> > int func(
> > - struct ctl_table *ctl,
> > + const struct ctl_table *ctl,
> > int write, void *buffer, size_t *lenp, loff_t *ppos)
> > { ... }
> >
> > In addition to the scripted changes some other changes are done:
> >
> > * The "typedef proc_handler" in include/linux/sysctl.h is changed to use
> > the "const ctl_table".
> >
> > * The prototypes of non-static handlers in header-files are adapted
> > to match the changes of their respective definitions.
> >
> > * kernel/watchdog.c: proc_watchdog_common()
> > This is called from a proc_handler itself and is als calling back
> > into another proc_handler, making it necessary to change it as part
> > of the proc_handler migration.
> >
> > No functional change.
> >
> > Signed-off-by: Thomas Weißschuh <linux@xxxxxxxxxxxxxx>
> Will test this in 0-day in [1] to avoid potential conflicts with all the
> other stuff going into linux-next and because it does not apply cleanly to
> sysctl-next. Don't expect any issues from 0-day as it is a
> non-functional trivial change.

Thanks!

> I'll use this patch as is when the time comes during the end of the
> merge window (at that point it should apply cleanly) and go into
>
> @Thomas: Can I ping you during the merge window to double check that
> there are no additional proc_handlers (without the const argument)
> that might not be present in today's linux-next?

Sure, I'll test it from time to time anyways.

> Best
>
> [1] https://git.kernel.org/pub/scm/linux/kernel/git/joel.granados/linux.git/log/?h=jag/constify_proc_handlers