linux-kernel - [patch 13/20] posix-timers: Document sys_clock

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Date:   Tue, 25 Apr 2023 20:49:16 +0200 (CEST)
From:   Thomas Gleixner <tglx@...utronix.de>
To:     LKML <linux-kernel@...r.kernel.org>
Cc:     Frederic Weisbecker <frederic@...nel.org>,
        Anna-Maria Behnsen <anna-maria@...utronix.de>,
        Peter Zijlstra <peterz@...radead.org>,
        Sebastian Siewior <bigeasy@...utronix.de>,
        syzbot+5c54bd3eb218bb595aa9@...kaller.appspotmail.com,
        Dmitry Vyukov <dvyukov@...gle.com>,
        Michael Kerrisk <mtk.manpages@...il.com>
Subject: [patch 13/20] posix-timers: Document sys_clock_settime() permissions in place

The documentation of sys_clock_settime() permissions is at a random place
and mostly word salad.

Remove it and add a concise comment into sys_clock_settime().

Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
---
 kernel/time/posix-timers.c |   11 ++++-------
 1 file changed, 4 insertions(+), 7 deletions(-)

--- a/kernel/time/posix-timers.c
+++ b/kernel/time/posix-timers.c
@@ -74,13 +74,6 @@ static const struct k_clock clock_realti
  *	    following: 1.) The k_itimer struct (sched.h) is used for
  *	    the timer.  2.) The list, it_lock, it_clock, it_id and
  *	    it_pid fields are not modified by timer code.
- *
- * Permissions: It is assumed that the clock_settime() function defined
- *	    for each clock will take care of permission checks.	 Some
- *	    clocks may be set able by any user (i.e. local process
- *	    clocks) others not.	 Currently the only set able clock we
- *	    have is CLOCK_REALTIME and its high res counter part, both of
- *	    which we beg off on and pass to do_sys_settimeofday().
  */
 static struct k_itimer *__lock_timer(timer_t timer_id, unsigned long *flags);
 
@@ -1165,6 +1158,10 @@ SYSCALL_DEFINE2(clock_settime, const clo
 	if (get_timespec64(&new_tp, tp))
 		return -EFAULT;
 
+	/*
+	 * Permission checks have to be done inside the clock specific
+	 * setter callback.
+	 */
 	return kc->clock_set(which_clock, &new_tp);
 }