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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 V7 20/21] alarmtimers: Remove the throttle mechanism from alarm_forward_now()
Date: Tue,  5 Nov 2024 09:14:56 +0100 (CET)	[thread overview]
Message-ID: <20241105064214.252443020@linutronix.de> (raw)
In-Reply-To: <20241105063544.565410398@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:[~2024-11-05  8:14 UTC|newest]

Thread overview: 50+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-11-05  8:14 [patch V7 00/21] posix-timers: Cure the SIG_IGN mess Thomas Gleixner
2024-11-05  8:14 ` [patch V7 01/21] posix-cpu-timers: Correctly update timer status in posix_cpu_timer_del() Thomas Gleixner
2024-11-05 12:02   ` Frederic Weisbecker
2024-11-07  1:31   ` [tip: timers/core] " tip-bot2 for Thomas Gleixner
2024-11-05  8:14 ` [patch V7 02/21] posix-timers: Make signal delivery consistent Thomas Gleixner
2024-11-07  1:31   ` [tip: timers/core] " tip-bot2 for Thomas Gleixner
2024-11-05  8:14 ` [patch V7 03/21] posix-timers: Make signal overrun accounting sensible Thomas Gleixner
2024-11-07  1:31   ` [tip: timers/core] " tip-bot2 for Thomas Gleixner
2024-11-05  8:14 ` [patch V7 04/21] posix-cpu-timers: Cleanup the firing logic Thomas Gleixner
2024-11-07  1:31   ` [tip: timers/core] " tip-bot2 for Thomas Gleixner
2024-11-05  8:14 ` [patch V7 05/21] posix-cpu-timers: Use dedicated flag for CPU timer nanosleep Thomas Gleixner
2024-11-07  1:31   ` [tip: timers/core] " tip-bot2 for Thomas Gleixner
2024-11-05  8:14 ` [patch V7 06/21] posix-timers: Add a refcount to struct k_itimer Thomas Gleixner
2024-11-07  1:31   ` [tip: timers/core] " tip-bot2 for Thomas Gleixner
2024-11-05  8:14 ` [patch V7 07/21] signal: Split up __sigqueue_alloc() Thomas Gleixner
2024-11-07  1:31   ` [tip: timers/core] " tip-bot2 for Thomas Gleixner
2024-11-05  8:14 ` [patch V7 08/21] signal: Provide posixtimer_sigqueue_init() Thomas Gleixner
2024-11-07  1:31   ` [tip: timers/core] " tip-bot2 for Thomas Gleixner
2024-11-05  8:14 ` [patch V7 09/21] posix-timers: Store PID type in the timer Thomas Gleixner
2024-11-07  1:31   ` [tip: timers/core] " tip-bot2 for Thomas Gleixner
2024-11-05  8:14 ` [patch V7 10/21] signal: Refactor send_sigqueue() Thomas Gleixner
2024-11-07  1:31   ` [tip: timers/core] " tip-bot2 for Thomas Gleixner
2024-11-05  8:14 ` [patch V7 11/21] signal: Replace resched_timer logic Thomas Gleixner
2024-11-05 12:08   ` Frederic Weisbecker
2024-11-07  1:31   ` [tip: timers/core] " tip-bot2 for Thomas Gleixner
2024-11-05  8:14 ` [patch V7 12/21] posix-timers: Embed sigqueue in struct k_itimer Thomas Gleixner
2024-11-07  1:31   ` [tip: timers/core] " tip-bot2 for Thomas Gleixner
2024-11-05  8:14 ` [patch V7 13/21] signal: Cleanup unused posix-timer leftovers Thomas Gleixner
2024-11-07  1:31   ` [tip: timers/core] " tip-bot2 for Thomas Gleixner
2024-11-05  8:14 ` [patch V7 14/21] posix-timers: Move sequence logic into struct k_itimer Thomas Gleixner
2024-11-07  1:31   ` [tip: timers/core] " tip-bot2 for Thomas Gleixner
2024-11-05  8:14 ` [patch V7 15/21] signal: Provide ignored_posix_timers list Thomas Gleixner
2024-11-07  1:31   ` [tip: timers/core] " tip-bot2 for Thomas Gleixner
2024-11-05  8:14 ` [patch V7 16/21] posix-timers: Handle ignored list on delete and exit Thomas Gleixner
2024-11-05 13:08   ` Frederic Weisbecker
2024-11-07  1:31   ` [tip: timers/core] " tip-bot2 for Thomas Gleixner
2024-11-05  8:14 ` [patch V7 17/21] signal: Handle ignored signals in do_sigaction(action != SIG_IGN) Thomas Gleixner
2024-11-07  1:31   ` [tip: timers/core] " tip-bot2 for Thomas Gleixner
2024-11-05  8:14 ` [patch V7 18/21] signal: Queue ignored posixtimers on ignore list Thomas Gleixner
2024-11-05 14:02   ` Frederic Weisbecker
2024-11-07  1:31   ` [tip: timers/core] " tip-bot2 for Thomas Gleixner
2024-11-05  8:14 ` [patch V7 19/21] posix-timers: Cleanup SIG_IGN workaround leftovers Thomas Gleixner
2024-11-05 14:26   ` Frederic Weisbecker
2024-11-07  1:31   ` [tip: timers/core] " tip-bot2 for Thomas Gleixner
2024-11-05  8:14 ` Thomas Gleixner [this message]
2024-11-05 14:29   ` [patch V7 20/21] alarmtimers: Remove the throttle mechanism from alarm_forward_now() Frederic Weisbecker
2024-11-07  1:31   ` [tip: timers/core] " tip-bot2 for Thomas Gleixner
2024-11-05  8:14 ` [patch V7 21/21] alarmtimers: Remove return value from alarm functions Thomas Gleixner
2024-11-05 14:34   ` Frederic Weisbecker
2024-11-07  1:31   ` [tip: timers/core] " tip-bot2 for Thomas Gleixner

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