Commit ebabeaf1 authored by Davidlohr Bueso's avatar Davidlohr Bueso Committed by sanglipeng1
Browse files

hrtimer: Ignore slack time for RT tasks in schedule_hrtimeout_range() 

stable inclusion
from stable-v5.10.210
commit 70ca0dbae4e9267c922d85dd87a889d55dd25962
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/IAE52H

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=70ca0dbae4e9267c922d85dd87a889d55dd25962



--------------------------------

commit 0c52310f upstream.

While in theory the timer can be triggered before expires + delta, for the
cases of RT tasks they really have no business giving any lenience for
extra slack time, so override any passed value by the user and always use
zero for schedule_hrtimeout_range() calls. Furthermore, this is similar to
what the nanosleep(2) family already does with current->timer_slack_ns.

Signed-off-by: default avatarDavidlohr Bueso <dave@stgolabs.net>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20230123173206.6764-3-dave@stgolabs.net


Signed-off-by: default avatarFelix Moessbauer <felix.moessbauer@siemens.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: default avatarsanglipeng1 <sanglipeng1@jd.com>
parent c0df8cb4

kernel/time/hrtimer.c

+11 −3
Original line number Diff line number Diff line
@@ -2161,7 +2161,7 @@ void __init hrtimers_init(void) 
/**

 * schedule_hrtimeout_range_clock - sleep until timeout

 * @expires:	timeout value (ktime_t)

 * @delta:	slack in expires timeout (ktime_t)

 * @delta:	slack in expires timeout (ktime_t) for SCHED_OTHER tasks

 * @mode:	timer mode

 * @clock_id:	timer clock to be used

 */
@@ -2188,6 +2188,13 @@ schedule_hrtimeout_range_clock(ktime_t *expires, u64 delta, 
		return -EINTR;

	}



	/*

	 * Override any slack passed by the user if under

	 * rt contraints.

	 */

	if (rt_task(current))

		delta = 0;



	hrtimer_init_sleeper_on_stack(&t, clock_id, mode);

	hrtimer_set_expires_range_ns(&t.timer, *expires, delta);

	hrtimer_sleeper_start_expires(&t, mode);
@@ -2207,7 +2214,7 @@ EXPORT_SYMBOL_GPL(schedule_hrtimeout_range_clock); 
/**

 * schedule_hrtimeout_range - sleep until timeout

 * @expires:	timeout value (ktime_t)

 * @delta:	slack in expires timeout (ktime_t)

 * @delta:	slack in expires timeout (ktime_t) for SCHED_OTHER tasks

 * @mode:	timer mode

 *

 * Make the current task sleep until the given expiry time has
@@ -2215,7 +2222,8 @@ EXPORT_SYMBOL_GPL(schedule_hrtimeout_range_clock); 
 * the current task state has been set (see set_current_state()).

 *

 * The @delta argument gives the kernel the freedom to schedule the

 * actual wakeup to a time that is both power and performance friendly.

 * actual wakeup to a time that is both power and performance friendly

 * for regular (non RT/DL) tasks.

 * The kernel give the normal best effort behavior for "@expires+@delta",

 * but may decide to fire the timer earlier, but no earlier than @expires.

 *