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Groups > linux.kernel > #1420936

Re: [patch 13/20] timer: Switch to a non cascading wheel

From Richard Cochran <richardcochran@gmail.com>
Newsgroups linux.kernel
Subject Re: [patch 13/20] timer: Switch to a non cascading wheel
Date 2016-06-13 16:40 +0200
Message-ID <rJBbY-7vM-9@gated-at.bofh.it> (permalink)
References <rJvJf-3OU-5@gated-at.bofh.it> <rJvJg-3OU-41@gated-at.bofh.it>
Organization linux.* mail to news gateway

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On Mon, Jun 13, 2016 at 08:41:00AM -0000, Thomas Gleixner wrote:
> +static inline struct timer_base *get_timer_base(u32 tflags)
> +{
> +	return get_timer_cpu_base(tflags, tflags & TIMER_BASEMASK);
> +}

This should rather be (tflags & TIMER_CPUMASK) to avoid using
per_cpu_ptr() with the TIMER_MIGRATING bit set in the CPU index.

The one caller in this patch is okay, since it already checks that
TIMER_MIGRATING is clear:

>  static struct timer_base *lock_timer_base(struct timer_list *timer,
> -					unsigned long *flags)
> +					  unsigned long *flags)
>  	__acquires(timer->base->lock)
>  {
>  	for (;;) {
> -		u32 tf = timer->flags;
>  		struct timer_base *base;
> +		u32 tf = timer->flags;
>  
>  		if (!(tf & TIMER_MIGRATING)) {
> -			base = per_cpu_ptr(&timer_bases, tf & TIMER_CPUMASK);
> +			base = get_timer_base(tf);

However, in patch #20, we'll have this in __mod_timer();

		/*
		 * Take the current timer_jiffies of base, but without holding
		 * the lock!
		 */
		base = get_timer_base(timer->flags);

Thanks,
Richard

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Thread

[patch 00/20] timer: Refactor the timer wheel Thomas Gleixner <tglx@linutronix.de> - 2016-06-13 10:50 +0200
  [patch 11/20] hlist: Add hlist_is_last_node() helper Thomas Gleixner <tglx@linutronix.de> - 2016-06-13 10:50 +0200
    Re: [patch 11/20] hlist: Add hlist_is_last_node() helper Paolo Bonzini <pbonzini@redhat.com> - 2016-06-13 12:30 +0200
  [patch 07/20] drivers/tty/mips_ejtag: Initialize timer as pinned Thomas Gleixner <tglx@linutronix.de> - 2016-06-13 10:50 +0200
  [patch 01/20] timer: Make pinned a timer property Thomas Gleixner <tglx@linutronix.de> - 2016-06-13 10:50 +0200
  [patch 17/20] tick/sched: Remove pointless empty function Thomas Gleixner <tglx@linutronix.de> - 2016-06-13 10:50 +0200
  [patch 05/20] driver/net/ethernet/tile: Initialize timer as pinned Thomas Gleixner <tglx@linutronix.de> - 2016-06-13 10:50 +0200
  [patch 15/20] timer: Move __run_timers() function Thomas Gleixner <tglx@linutronix.de> - 2016-06-13 10:50 +0200
  [patch 12/20] timer: Give a few structs and members proper names Thomas Gleixner <tglx@linutronix.de> - 2016-06-13 10:50 +0200
  [patch 04/20] cpufreq/powernv: Initialize timer as pinned Thomas Gleixner <tglx@linutronix.de> - 2016-06-13 10:50 +0200
    Re: [patch 04/20] cpufreq/powernv: Initialize timer as pinned Arjan van de Ven <arjanvandeven@gmail.com> - 2016-06-13 15:20 +0200
  [patch 13/20] timer: Switch to a non cascading wheel Thomas Gleixner <tglx@linutronix.de> - 2016-06-13 10:50 +0200
    Re: [patch 13/20] timer: Switch to a non cascading wheel Peter Zijlstra <peterz@infradead.org> - 2016-06-13 13:50 +0200
      Re: [patch 13/20] timer: Switch to a non cascading wheel Thomas Gleixner <tglx@linutronix.de> - 2016-06-13 14:40 +0200
        Re: [patch 13/20] timer: Switch to a non cascading wheel Eric Dumazet <edumazet@google.com> - 2016-06-13 14:50 +0200
          Re: [patch 13/20] timer: Switch to a non cascading wheel Thomas Gleixner <tglx@linutronix.de> - 2016-06-13 16:40 +0200
        Re: [patch 13/20] timer: Switch to a non cascading wheel Ingo Molnar <mingo@kernel.org> - 2016-06-14 12:20 +0200
          Re: [patch 13/20] timer: Switch to a non cascading wheel Thomas Gleixner <tglx@linutronix.de> - 2016-06-14 18:40 +0200
            Re: [patch 13/20] timer: Switch to a non cascading wheel Arjan van de Ven <arjanvandeven@gmail.com> - 2016-06-14 19:20 +0200
              Re: [patch 13/20] timer: Switch to a non cascading wheel Thomas Gleixner <tglx@linutronix.de> - 2016-06-14 20:10 +0200
                Re: [patch 13/20] timer: Switch to a non cascading wheel Peter Zijlstra <peterz@infradead.org> - 2016-06-14 22:40 +0200
                Re: [patch 13/20] timer: Switch to a non cascading wheel Peter Zijlstra <peterz@infradead.org> - 2016-06-14 22:50 +0200
                Re: [patch 13/20] timer: Switch to a non cascading wheel Eric Dumazet <edumazet@google.com> - 2016-06-14 23:20 +0200
                Re: [patch 13/20] timer: Switch to a non cascading wheel Thomas Gleixner <tglx@linutronix.de> - 2016-06-15 17:00 +0200
                Re: [patch 13/20] timer: Switch to a non cascading wheel Arjan van de Ven <arjanvandeven@gmail.com> - 2016-06-15 17:00 +0200
                Re: [patch 13/20] timer: Switch to a non cascading wheel Thomas Gleixner <tglx@linutronix.de> - 2016-06-15 18:50 +0200
                Re: [patch 13/20] timer: Switch to a non cascading wheel Thomas Gleixner <tglx@linutronix.de> - 2016-06-16 17:50 +0200
                Re: [patch 13/20] timer: Switch to a non cascading wheel "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2016-06-16 18:10 +0200
                Re: [patch 13/20] timer: Switch to a non cascading wheel Peter Zijlstra <peterz@infradead.org> - 2016-06-16 20:20 +0200
                Re: [patch 13/20] timer: Switch to a non cascading wheel "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2016-06-17 02:50 +0200
                Re: [patch 13/20] timer: Switch to a non cascading wheel "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2016-06-17 06:10 +0200
                Re: [patch 13/20] timer: Switch to a non cascading wheel Arjan van de Ven <arjanvandeven@gmail.com> - 2016-06-16 18:10 +0200
                Re: [patch 13/20] timer: Switch to a non cascading wheel Thomas Gleixner <tglx@linutronix.de> - 2016-06-16 18:20 +0200
                Re: [patch 13/20] timer: Switch to a non cascading wheel Eric Dumazet <edumazet@google.com> - 2016-06-15 17:10 +0200
    Re: [patch 13/20] timer: Switch to a non cascading wheel Richard Cochran <richardcochran@gmail.com> - 2016-06-13 16:40 +0200
      Re: [patch 13/20] timer: Switch to a non cascading wheel Thomas Gleixner <tglx@linutronix.de> - 2016-06-13 16:50 +0200
  [patch 14/20] timer: Remove slack leftovers Thomas Gleixner <tglx@linutronix.de> - 2016-06-13 10:50 +0200
  [patch 18/20] timer: Forward wheel clock whenever possible Thomas Gleixner <tglx@linutronix.de> - 2016-06-13 10:50 +0200
    Re: [patch 18/20] timer: Forward wheel clock whenever possible Richard Cochran <richardcochran@gmail.com> - 2016-06-13 17:20 +0200
      Re: [patch 18/20] timer: Forward wheel clock whenever possible Thomas Gleixner <tglx@linutronix.de> - 2016-06-13 17:30 +0200
  [patch 06/20] drivers/tty/metag_da: Initialize timer as pinned Thomas Gleixner <tglx@linutronix.de> - 2016-06-13 11:00 +0200
    Re: [patch 06/20] drivers/tty/metag_da: Initialize timer as pinned Arjan van de Ven <arjanvandeven@gmail.com> - 2016-06-13 15:20 +0200
  [patch 03/20] x86/mce: Initialize timer as pinned Thomas Gleixner <tglx@linutronix.de> - 2016-06-13 11:00 +0200
  [patch 08/20] net/ipv4/inet: Initialize timers as pinned Thomas Gleixner <tglx@linutronix.de> - 2016-06-13 11:00 +0200
  [patch 02/20] x86/apic/uv: Initialize timer as pinned Thomas Gleixner <tglx@linutronix.de> - 2016-06-13 11:00 +0200
  Re: [patch 00/20] timer: Refactor the timer wheel Eric Dumazet <edumazet@google.com> - 2016-06-13 16:20 +0200
  Re: [patch 00/20] timer: Refactor the timer wheel "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2016-06-13 18:20 +0200
    Re: [patch 00/20] timer: Refactor the timer wheel "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2016-06-15 17:20 +0200
      Re: [patch 00/20] timer: Refactor the timer wheel Thomas Gleixner <tglx@linutronix.de> - 2016-06-15 19:10 +0200
        Re: [patch 00/20] timer: Refactor the timer wheel "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2016-06-15 22:30 +0200

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