mirror of https://lore.kernel.org/lkml/
 help / color / mirror / Atom feed
From: Thomas Gleixner <tglx@linutronix.de>
To: LKML <linux-kernel@vger.kernel.org>
Cc: Anna-Maria Behnsen <anna-maria@linutronix.de>,
	Frederic Weisbecker <frederic@kernel.org>,
	John Stultz <jstultz@google.com>,
	Peter Zijlstra <peterz@infradead.org>,
	Ingo Molnar <mingo@kernel.org>, Stephen Boyd <sboyd@kernel.org>,
	Eric Biederman <ebiederm@xmission.com>,
	Oleg Nesterov <oleg@redhat.com>
Subject: [patch v4 26/27] alarmtimers: Remove the throttle mechanism from alarm_forward_now()
Date: Fri, 27 Sep 2024 10:49:11 +0200 (CEST)	[thread overview]
Message-ID: <20240927084818.487794783@linutronix.de> (raw)
In-Reply-To: <20240927083900.989915582@linutronix.de>

From: Thomas Gleixner <tglx@linutronix.de>

Now that ignored posix timer signals are requeued and the timers are
rearmed on signal delivery the workaround to keep such timers alive and
self rearm them is not longer required.

Remove the unused alarm timer parts.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>

---
 kernel/time/alarmtimer.c |   28 ++--------------------------
 1 file changed, 2 insertions(+), 26 deletions(-)
---
--- a/kernel/time/alarmtimer.c
+++ b/kernel/time/alarmtimer.c
@@ -467,35 +467,11 @@ u64 alarm_forward(struct alarm *alarm, k
 }
 EXPORT_SYMBOL_GPL(alarm_forward);
 
-static u64 __alarm_forward_now(struct alarm *alarm, ktime_t interval, bool throttle)
+u64 alarm_forward_now(struct alarm *alarm, ktime_t interval)
 {
 	struct alarm_base *base = &alarm_bases[alarm->type];
-	ktime_t now = base->get_ktime();
-
-	if (IS_ENABLED(CONFIG_HIGH_RES_TIMERS) && throttle) {
-		/*
-		 * Same issue as with posix_timer_fn(). Timers which are
-		 * periodic but the signal is ignored can starve the system
-		 * with a very small interval. The real fix which was
-		 * promised in the context of posix_timer_fn() never
-		 * materialized, but someone should really work on it.
-		 *
-		 * To prevent DOS fake @now to be 1 jiffy out which keeps
-		 * the overrun accounting correct but creates an
-		 * inconsistency vs. timer_gettime(2).
-		 */
-		ktime_t kj = NSEC_PER_SEC / HZ;
 
-		if (interval < kj)
-			now = ktime_add(now, kj);
-	}
-
-	return alarm_forward(alarm, now, interval);
-}
-
-u64 alarm_forward_now(struct alarm *alarm, ktime_t interval)
-{
-	return __alarm_forward_now(alarm, interval, false);
+	return alarm_forward(alarm, base->get_ktime(), interval);
 }
 EXPORT_SYMBOL_GPL(alarm_forward_now);
 


  parent reply	other threads:[~2024-09-27  8:49 UTC|newest]

Thread overview: 36+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-09-27  8:48 [patch v4 00/27] posix-timers: Cure the SIG_IGN mess Thomas Gleixner
2024-09-27  8:48 ` [patch v4 01/27] signal: Confine POSIX_TIMERS properly Thomas Gleixner
2024-09-27 12:21   ` Frederic Weisbecker
2024-09-27  8:48 ` [patch v4 02/27] signal: Prevent user space from setting si_sys_private Thomas Gleixner
2024-09-27 12:37   ` Frederic Weisbecker
2024-09-27 13:40   ` Eric W. Biederman
2024-09-27  8:48 ` [patch v4 03/27] signal: Get rid of resched_timer logic Thomas Gleixner
2024-09-27 13:08   ` Frederic Weisbecker
2024-09-27 13:53   ` Eric W. Biederman
2024-09-27  8:48 ` [patch v4 04/27] posix-timers: Cure si_sys_private race Thomas Gleixner
2024-09-27 14:02   ` Eric W. Biederman
2024-09-27  8:48 ` [patch v4 05/27] signal: Allow POSIX timer signals to be dropped Thomas Gleixner
2024-09-27  8:48 ` [patch v4 06/27] posix-timers: Drop signal if timer has been deleted or reprogrammed Thomas Gleixner
2024-09-27  8:48 ` [patch v4 07/27] posix-timers: Rename k_itimer::it_requeue_pending Thomas Gleixner
2024-09-27  8:48 ` [patch v4 08/27] posix-timers: Add proper state tracking Thomas Gleixner
2024-09-27  8:48 ` [patch v4 09/27] posix-timers: Make signal delivery consistent Thomas Gleixner
2024-09-27  8:48 ` [patch v4 10/27] posix-timers: Make signal overrun accounting sensible Thomas Gleixner
2024-09-27  8:48 ` [patch v4 11/27] posix-cpu-timers: Use dedicated flag for CPU timer nanosleep Thomas Gleixner
2024-09-27  8:48 ` [patch v4 12/27] posix-timers: Add a refcount to struct k_itimer Thomas Gleixner
2024-09-27  8:48 ` [patch v4 13/27] signal: Split up __sigqueue_alloc() Thomas Gleixner
2024-09-27  8:48 ` [patch v4 14/27] signal: Provide posixtimer_sigqueue_init() Thomas Gleixner
2024-09-27  8:48 ` [patch v4 15/27] signal: Add sys_private_ptr to siginfo::_sifields:: _timer Thomas Gleixner
2024-09-27  8:48 ` [patch v4 16/27] posix-timers: Store PID type in the timer Thomas Gleixner
2024-09-27  8:48 ` [patch v4 17/27] signal: Refactor send_sigqueue() Thomas Gleixner
2024-09-27  8:49 ` [patch v4 18/27] posix-timers: Embed sigqueue in struct k_itimer Thomas Gleixner
2024-09-27  8:49 ` [patch v4 19/27] signal: Cleanup unused posix-timer leftovers Thomas Gleixner
2024-09-27  8:49 ` [patch v4 20/27] signal: Add task argument to flush_sigqueue_mask() Thomas Gleixner
2024-09-27  8:49 ` [patch v4 21/27] signal: Provide ignored_posix_timers list Thomas Gleixner
2024-09-27  8:49 ` [patch v4 22/27] posix-timers: Handle ignored list on delete and exit Thomas Gleixner
2024-09-27  8:49 ` [patch v4 23/27] signal: Handle ignored signals in do_sigaction(action != SIG_IGN) Thomas Gleixner
2024-09-27  8:49 ` [patch v4 24/27] signal: Queue ignored posixtimers on ignore list Thomas Gleixner
2024-09-27  8:49 ` [patch v4 25/27] posix-timers: Cleanup SIG_IGN workaround leftovers Thomas Gleixner
2024-09-27  8:49 ` Thomas Gleixner [this message]
2024-09-27  8:49 ` [patch v4 27/27] alarmtimers: Remove return value from alarm functions Thomas Gleixner
2024-09-27 14:39 ` [patch v4 00/27] posix-timers: Cure the SIG_IGN mess Eric W. Biederman
2024-09-27 19:24   ` Thomas Gleixner

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20240927084818.487794783@linutronix.de \
    --to=tglx@linutronix.de \
    --cc=anna-maria@linutronix.de \
    --cc=ebiederm@xmission.com \
    --cc=frederic@kernel.org \
    --cc=jstultz@google.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=mingo@kernel.org \
    --cc=oleg@redhat.com \
    --cc=peterz@infradead.org \
    --cc=sboyd@kernel.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox

Powered by JetHome