Mailing List Archive: Linux: Kernel

[PATCH 1/2] hrtimer: correct a few numbers in comments and printk outputs

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u.kleine-koenig at pengutronix

Nov 20, 2009, 11:23 AM

Post #1 of 7 (209 views)
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[PATCH 1/2] hrtimer: correct a few numbers in comments and printk outputs

Signed-off-by: Uwe Kleine-König <u.kleine-koenig [at] pengutronix>
Cc: Thomas Gleixner <tglx [at] linutronix>
Cc: Ingo Molnar <mingo [at] elte>
Cc: Peter Zijlstra <a.p.zijlstra [at] chello>
Cc: Luming Yu <luming.yu [at] gmail>
---
kernel/hrtimer.c | 4 ++--
kernel/time/tick-oneshot.c | 4 ++--
2 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/kernel/hrtimer.c b/kernel/hrtimer.c
index 3e1c36e..4443295 100644
--- a/kernel/hrtimer.c
+++ b/kernel/hrtimer.c
@@ -1220,7 +1220,7 @@ static void __run_hrtimer(struct hrtimer *timer, ktime_t *now)
static int force_clock_reprogram;

/*
- * After 5 iteration's attempts, we consider that hrtimer_interrupt()
+ * After 4 iteration's attempts, we consider that hrtimer_interrupt()
* is hanging, which could happen with something that slows the interrupt
* such as the tracing. Then we force the clock reprogramming for each future
* hrtimer interrupts to avoid infinite loops and use the min_delta_ns
@@ -1257,7 +1257,7 @@ void hrtimer_interrupt(struct clock_event_device *dev)
dev->next_event.tv64 = KTIME_MAX;

retry:
- /* 5 retries is enough to notice a hang */
+ /* 4 retries is enough to notice a hang */
if (!(++nr_retries % 5))
hrtimer_interrupt_hanging(dev, ktime_sub(ktime_get(), now));

diff --git a/kernel/time/tick-oneshot.c b/kernel/time/tick-oneshot.c
index a96c0e2..2dd23c3 100644
--- a/kernel/time/tick-oneshot.c
+++ b/kernel/time/tick-oneshot.c
@@ -39,7 +39,7 @@ int tick_dev_program_event(struct clock_event_device *dev, ktime_t expires,

/*
* We tried 2 times to program the device with the given
- * min_delta_ns. If that's not working then we double it
+ * min_delta_ns. If that's not working then we increase it
* and emit a warning.
*/
if (++i > 2) {
@@ -52,7 +52,7 @@ int tick_dev_program_event(struct clock_event_device *dev, ktime_t expires,
printk(KERN_WARNING
"CE: %s increasing min_delta_ns to %lu nsec\n",
dev->name ? dev->name : "?",
- dev->min_delta_ns << 1);
+ dev->min_delta_ns);

i = 0;
}
--
1.6.5.2

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akpm at linux-foundation

Nov 23, 2009, 3:25 PM

Post #2 of 7 (196 views)
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Re: [PATCH 1/2] hrtimer: correct a few numbers in comments and printk outputs [In reply to]

On Fri, 20 Nov 2009 20:23:39 +0100
Uwe Kleine-K__nig <u.kleine-koenig [at] pengutronix> wrote:

> @@ -52,7 +52,7 @@ int tick_dev_program_event(struct clock_event_device *dev, ktime_t expires,
> printk(KERN_WARNING
> "CE: %s increasing min_delta_ns to %lu nsec\n",
> dev->name ? dev->name : "?",
> - dev->min_delta_ns << 1);
> + dev->min_delta_ns);
>
> i = 0;
> }

This one's already in linux-next:

@@ -50,9 +50,9 @@ int tick_dev_program_event(struct clock_
dev->min_delta_ns += dev->min_delta_ns >> 1;

printk(KERN_WARNING
- "CE: %s increasing min_delta_ns to %lu nsec\n",
+ "CE: %s increasing min_delta_ns to %llu nsec\n",
dev->name ? dev->name : "?",
- dev->min_delta_ns << 1);
+ (unsigned long long) dev->min_delta_ns << 1);

i = 0;
}
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u.kleine-koenig at pengutronix

Nov 24, 2009, 2:14 AM

Post #3 of 7 (194 views)
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Re: [PATCH 1/2] hrtimer: correct a few numbers in comments and printk outputs [In reply to]

Hello Andrew,

On Mon, Nov 23, 2009 at 03:25:16PM -0800, Andrew Morton wrote:
> On Fri, 20 Nov 2009 20:23:39 +0100
> Uwe Kleine-K__nig <u.kleine-koenig [at] pengutronix> wrote:
>
> > @@ -52,7 +52,7 @@ int tick_dev_program_event(struct clock_event_device *dev, ktime_t expires,
> > printk(KERN_WARNING
> > "CE: %s increasing min_delta_ns to %lu nsec\n",
> > dev->name ? dev->name : "?",
> > - dev->min_delta_ns << 1);
> > + dev->min_delta_ns);
> >
> > i = 0;
> > }
>
> This one's already in linux-next:
>
> @@ -50,9 +50,9 @@ int tick_dev_program_event(struct clock_
> dev->min_delta_ns += dev->min_delta_ns >> 1;
>
> printk(KERN_WARNING
> - "CE: %s increasing min_delta_ns to %lu nsec\n",
> + "CE: %s increasing min_delta_ns to %llu nsec\n",
> dev->name ? dev->name : "?",
> - dev->min_delta_ns << 1);
> + (unsigned long long) dev->min_delta_ns << 1);
'<< 1' is wrong here, too.

Best regards
Uwe

--
Pengutronix e.K. | Uwe Kleine-K�nig |
Industrial Linux Solutions | http://www.pengutronix.de/ |
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akpm at linux-foundation

Nov 25, 2009, 11:56 AM

Post #4 of 7 (186 views)
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Re: [PATCH 1/2] hrtimer: correct a few numbers in comments and printk outputs [In reply to]

On Tue, 24 Nov 2009 11:14:03 +0100
Uwe Kleine-K__nig <u.kleine-koenig [at] pengutronix> wrote:

> Hello Andrew,
>
> On Mon, Nov 23, 2009 at 03:25:16PM -0800, Andrew Morton wrote:
> > On Fri, 20 Nov 2009 20:23:39 +0100
> > Uwe Kleine-K__nig <u.kleine-koenig [at] pengutronix> wrote:
> >
> > > @@ -52,7 +52,7 @@ int tick_dev_program_event(struct clock_event_device *dev, ktime_t expires,
> > > printk(KERN_WARNING
> > > "CE: %s increasing min_delta_ns to %lu nsec\n",
> > > dev->name ? dev->name : "?",
> > > - dev->min_delta_ns << 1);
> > > + dev->min_delta_ns);
> > >
> > > i = 0;
> > > }
> >
> > This one's already in linux-next:
> >
> > @@ -50,9 +50,9 @@ int tick_dev_program_event(struct clock_
> > dev->min_delta_ns += dev->min_delta_ns >> 1;
> >
> > printk(KERN_WARNING
> > - "CE: %s increasing min_delta_ns to %lu nsec\n",
> > + "CE: %s increasing min_delta_ns to %llu nsec\n",
> > dev->name ? dev->name : "?",
> > - dev->min_delta_ns << 1);
> > + (unsigned long long) dev->min_delta_ns << 1);
> '<< 1' is wrong here, too.
>

What's wrong with it? That leftshift appears to be to compensate for
the rightshift a few lines above.

That change was unobvious and unchangelogged, so here we are again.
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tglx at linutronix

Nov 25, 2009, 12:18 PM

Post #5 of 7 (187 views)
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Re: [PATCH 1/2] hrtimer: correct a few numbers in comments and printk outputs [In reply to]

On Wed, 25 Nov 2009, Andrew Morton wrote:

> On Tue, 24 Nov 2009 11:14:03 +0100
> Uwe Kleine-K__nig <u.kleine-koenig [at] pengutronix> wrote:
>
> > Hello Andrew,
> >
> > On Mon, Nov 23, 2009 at 03:25:16PM -0800, Andrew Morton wrote:
> > > On Fri, 20 Nov 2009 20:23:39 +0100
> > > Uwe Kleine-K__nig <u.kleine-koenig [at] pengutronix> wrote:
> > >
> > > > @@ -52,7 +52,7 @@ int tick_dev_program_event(struct clock_event_device *dev, ktime_t expires,
> > > > printk(KERN_WARNING
> > > > "CE: %s increasing min_delta_ns to %lu nsec\n",
> > > > dev->name ? dev->name : "?",
> > > > - dev->min_delta_ns << 1);
> > > > + dev->min_delta_ns);
> > > >
> > > > i = 0;
> > > > }
> > >
> > > This one's already in linux-next:
> > >
> > > @@ -50,9 +50,9 @@ int tick_dev_program_event(struct clock_
> > > dev->min_delta_ns += dev->min_delta_ns >> 1;
> > >
> > > printk(KERN_WARNING
> > > - "CE: %s increasing min_delta_ns to %lu nsec\n",
> > > + "CE: %s increasing min_delta_ns to %llu nsec\n",
> > > dev->name ? dev->name : "?",
> > > - dev->min_delta_ns << 1);
> > > + (unsigned long long) dev->min_delta_ns << 1);
> > '<< 1' is wrong here, too.
> >
>
> What's wrong with it? That leftshift appears to be to compensate for
> the rightshift a few lines above.
>
> That change was unobvious and unchangelogged, so here we are again.

That's actually my fault. In commit 61c22c34 I removed the WARN_ON
which we put there to gather data on kerneloops.org for a while and
did not fix the printk format string.

Will take care of it. Thanks,

tglx
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akpm at linux-foundation

Nov 25, 2009, 1:18 PM

Post #6 of 7 (183 views)
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Re: [PATCH 1/2] hrtimer: correct a few numbers in comments and printk outputs [In reply to]

On Wed, 25 Nov 2009 21:18:39 +0100 (CET)
Thomas Gleixner <tglx [at] linutronix> wrote:

> On Wed, 25 Nov 2009, Andrew Morton wrote:
>
> > On Tue, 24 Nov 2009 11:14:03 +0100
> > Uwe Kleine-K__nig <u.kleine-koenig [at] pengutronix> wrote:
> >
> > > Hello Andrew,
> > >
> > > On Mon, Nov 23, 2009 at 03:25:16PM -0800, Andrew Morton wrote:
> > > > On Fri, 20 Nov 2009 20:23:39 +0100
> > > > Uwe Kleine-K__nig <u.kleine-koenig [at] pengutronix> wrote:
> > > >
> > > > > @@ -52,7 +52,7 @@ int tick_dev_program_event(struct clock_event_device *dev, ktime_t expires,
> > > > > printk(KERN_WARNING
> > > > > "CE: %s increasing min_delta_ns to %lu nsec\n",
> > > > > dev->name ? dev->name : "?",
> > > > > - dev->min_delta_ns << 1);
> > > > > + dev->min_delta_ns);
> > > > >
> > > > > i = 0;
> > > > > }
> > > >
> > > > This one's already in linux-next:
> > > >
> > > > @@ -50,9 +50,9 @@ int tick_dev_program_event(struct clock_
> > > > dev->min_delta_ns += dev->min_delta_ns >> 1;
> > > >
> > > > printk(KERN_WARNING
> > > > - "CE: %s increasing min_delta_ns to %lu nsec\n",
> > > > + "CE: %s increasing min_delta_ns to %llu nsec\n",
> > > > dev->name ? dev->name : "?",
> > > > - dev->min_delta_ns << 1);
> > > > + (unsigned long long) dev->min_delta_ns << 1);
> > > '<< 1' is wrong here, too.
> > >
> >
> > What's wrong with it? That leftshift appears to be to compensate for
> > the rightshift a few lines above.
> >
> > That change was unobvious and unchangelogged, so here we are again.
>
> That's actually my fault. In commit 61c22c34 I removed the WARN_ON
> which we put there to gather data on kerneloops.org for a while and
> did not fix the printk format string.
>

The issue is not the format string. I'm wondering why Uwe removed that
left-shift of dev->min_delta_ns.

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tglx at linutronix

Nov 25, 2009, 2:07 PM

Post #7 of 7 (187 views)
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Re: [PATCH 1/2] hrtimer: correct a few numbers in comments and printk outputs [In reply to]

On Wed, 25 Nov 2009, Andrew Morton wrote:
> On Wed, 25 Nov 2009 21:18:39 +0100 (CET)
> Thomas Gleixner <tglx [at] linutronix> wrote:
> > > > > @@ -50,9 +50,9 @@ int tick_dev_program_event(struct clock_
> > > > > dev->min_delta_ns += dev->min_delta_ns >> 1;
> > > > >
> > > > > printk(KERN_WARNING
> > > > > - "CE: %s increasing min_delta_ns to %lu nsec\n",
> > > > > + "CE: %s increasing min_delta_ns to %llu nsec\n",
> > > > > dev->name ? dev->name : "?",
> > > > > - dev->min_delta_ns << 1);
> > > > > + (unsigned long long) dev->min_delta_ns << 1);
> > > > '<< 1' is wrong here, too.
> > > >
> > >
> > > What's wrong with it? That leftshift appears to be to compensate for
> > > the rightshift a few lines above.
> > >
> > > That change was unobvious and unchangelogged, so here we are again.
> >
> > That's actually my fault. In commit 61c22c34 I removed the WARN_ON
> > which we put there to gather data on kerneloops.org for a while and
> > did not fix the printk format string.
> >
>
> The issue is not the format string. I'm wondering why Uwe removed that
> left-shift of dev->min_delta_ns.

Sorry, I'm confused: I did not fix the argument. The printk was
actually before the code which adjusted the min_delta_ns in the old
WARN_ON case. When I removed the WARN_ON I moved the printk down and
kept the << 1 which is crap. We want to print the new value not the
double of it.

Thanks,

tglx
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