linux-kernel - Re: [PATCH 20/23] y2038: move itimer reset into itimer.c

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Date:   Mon, 11 Nov 2019 11:57:52 +0100
From:   Arnd Bergmann <arnd@...db.de>
To:     Ondrej Mosnacek <omosnace@...hat.com>
Cc:     y2038 Mailman List <y2038@...ts.linaro.org>,
        John Stultz <john.stultz@...aro.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Paul Moore <paul@...l-moore.com>,
        Stephen Smalley <sds@...ho.nsa.gov>,
        Eric Paris <eparis@...isplace.org>,
        Linux kernel mailing list <linux-kernel@...r.kernel.org>,
        Stephen Boyd <sboyd@...nel.org>,
        Sebastian Andrzej Siewior <bigeasy@...utronix.de>,
        Ingo Molnar <mingo@...nel.org>,
        Anna-Maria Gleixner <anna-maria@...utronix.de>,
        Al Viro <viro@...iv.linux.org.uk>,
        SElinux list <selinux@...r.kernel.org>
Subject: Re: [PATCH 20/23] y2038: move itimer reset into itimer.c

On Sun, Nov 10, 2019 at 12:07 AM Ondrej Mosnacek <omosnace@...hat.com> wrote:
>
> On Sat, Nov 9, 2019 at 10:03 PM Arnd Bergmann <arnd@...db.de> wrote:
> >
> > On Sat, Nov 9, 2019 at 2:43 PM Ondrej Mosnacek <omosnace@...hat.com> wrote:
> >
> > > > -struct itimerval;
> > > > -extern int do_setitimer(int which, struct itimerval *value,
> > > > -                       struct itimerval *ovalue);
> > > > -extern int do_getitimer(int which, struct itimerval *value);
> > > > +#ifdef CONFIG_POSIX_TIMERS
> > > > +extern void clear_itimer(void);
> > > > +#else
> > > > +static inline void clear_itimer(void) {}
> > > > +#endif
> > > >
> >
> > > > @@ -249,6 +249,17 @@ int do_setitimer(int which, struct itimerval *value, struct itimerval *ovalue)
> > > >         return 0;
> > > >  }
> > > >
> > > > +#ifdef CONFIG_SECURITY_SELINUX
> > >
> > > Did you mean "#ifdef CONFIG_POSIX_TIMERS" here to match the header?
> >
> > No, this part is intentional, CONFIG_POSIX_TIMERS already controls
> > whether itimer.c is
> > compiled in the first place, but this function is only needed when called from
> > the selinux driver.
>
> All right, but you declare the function in time.h even if
> CONFIG_SECURITY_SELINUX is not enabled... it is kind of awkward when
> it can happen that the function is declared but not defined anywhere
> (even if it shouldn't be used by new users). Maybe you could at least
> put the header declaration/definition inside #ifdef
> CONFIG_SECURITY_SELINUX as well so it is clear that this function is
> intended for SELinux only?

I don't see that as a problem, we rarely put declarations inside of an #ifdef.
The main effect that would have is forcing any file that includes linux/time.h
to be rebuilt when selinux is turned on or off in the .config.

     Arnd