* tip/master merge problem?
@ 2008-12-31 22:08 Mike Travis
2009-01-02 16:06 ` Ingo Molnar
0 siblings, 1 reply; 2+ messages in thread
From: Mike Travis @ 2008-12-31 22:08 UTC (permalink / raw)
To: Ingo Molnar; +Cc: Rusty Russell, LKML
Hi Ingo,
I found this code snippet in kernel/sched.c in the tip/master tree. It
appears to be a merge mistake: (cut and pasted - no tabs)
292 /*
293 * If this cpu is the one which updates jiffies, then
294 * give up the assignment and let it be taken by the
295 * cpu which runs the tick timer next, which might be
296 * this cpu as well. If we don't drop this here the
297 * jiffies might be stale and do_timer() never
298 * invoked.
299 */
300 if (cpu == tick_do_timer_cpu)
301 tick_do_timer_cpu = TICK_DO_TIMER_NONE;
302
303 if (delta_jiffies > 1)
304
305 /* Skip reprogram of event if its not changed */
306 if (ts->tick_stopped && ktime_equal(expires, dev->next_event))
307 goto out;
308
309 cpumask_set_cpu(cpu, nohz_cpu_mask);
I think the "Skip reprogram" was inserted into the middle of a previous
if-then statement.
git blames it on:
00147449 (Woodruff, Richard 2008-12-01 14:18:11 -0800 292) /*
00147449 (Woodruff, Richard 2008-12-01 14:18:11 -0800 293) * If this cpu is the one which updates jiffies, then
00147449 (Woodruff, Richard 2008-12-01 14:18:11 -0800 294) * give up the assignment and let it be taken by the
00147449 (Woodruff, Richard 2008-12-01 14:18:11 -0800 295) * cpu which runs the tick timer next, which might be
00147449 (Woodruff, Richard 2008-12-01 14:18:11 -0800 296) * this cpu as well. If we don't drop this here the
00147449 (Woodruff, Richard 2008-12-01 14:18:11 -0800 297) * jiffies might be stale and do_timer() never
00147449 (Woodruff, Richard 2008-12-01 14:18:11 -0800 298) * invoked.
00147449 (Woodruff, Richard 2008-12-01 14:18:11 -0800 299) */
00147449 (Woodruff, Richard 2008-12-01 14:18:11 -0800 300) if (cpu == tick_do_timer_cpu)
00147449 (Woodruff, Richard 2008-12-01 14:18:11 -0800 301) tick_do_timer_cpu = TICK_DO_TIMER_NONE;
00147449 (Woodruff, Richard 2008-12-01 14:18:11 -0800 302)
6ba9b346 (Ingo Molnar 2007-02-19 18:11:56 +0000 303) if (delta_jiffies > 1)
00147449 (Woodruff, Richard 2008-12-01 14:18:11 -0800 304)
00147449 (Woodruff, Richard 2008-12-01 14:18:11 -0800 305) /* Skip reprogram of event if its not changed */
00147449 (Woodruff, Richard 2008-12-01 14:18:11 -0800 306) if (ts->tick_stopped && ktime_equal(expires, dev->next_event))
00147449 (Woodruff, Richard 2008-12-01 14:18:11 -0800 307) goto out;
00147449 (Woodruff, Richard 2008-12-01 14:18:11 -0800 308)
6a7b3dc3 (Rusty Russell 2008-11-25 02:35:04 +1030 309) cpumask_set_cpu(cpu, nohz_cpu_mask);
I've Cc'd both interested parties.
Thanks,
Mike
^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: tip/master merge problem?
2008-12-31 22:08 tip/master merge problem? Mike Travis
@ 2009-01-02 16:06 ` Ingo Molnar
0 siblings, 0 replies; 2+ messages in thread
From: Ingo Molnar @ 2009-01-02 16:06 UTC (permalink / raw)
To: Mike Travis; +Cc: Rusty Russell, LKML
* Mike Travis <travis@sgi.com> wrote:
>
> Hi Ingo,
>
> I found this code snippet in kernel/sched.c in the tip/master tree. It
> appears to be a merge mistake: (cut and pasted - no tabs)
>
> 292 /*
> 293 * If this cpu is the one which updates jiffies, then
> 294 * give up the assignment and let it be taken by the
> 295 * cpu which runs the tick timer next, which might be
> 296 * this cpu as well. If we don't drop this here the
> 297 * jiffies might be stale and do_timer() never
> 298 * invoked.
> 299 */
> 300 if (cpu == tick_do_timer_cpu)
> 301 tick_do_timer_cpu = TICK_DO_TIMER_NONE;
> 302
> 303 if (delta_jiffies > 1)
> 304
> 305 /* Skip reprogram of event if its not changed */
> 306 if (ts->tick_stopped && ktime_equal(expires, dev->next_event))
> 307 goto out;
> 308
> 309 cpumask_set_cpu(cpu, nohz_cpu_mask);
>
> I think the "Skip reprogram" was inserted into the middle of a previous
> if-then statement.
indeed, this is plain broken. It happened to build and boot but still it's
broken.
> git blames it on:
> 00147449 (Woodruff, Richard 2008-12-01 14:18:11 -0800 292) /*
> 00147449 (Woodruff, Richard 2008-12-01 14:18:11 -0800 293) * If this cpu is the one which updates jiffies, then
> 00147449 (Woodruff, Richard 2008-12-01 14:18:11 -0800 294) * give up the assignment and let it be taken by the
> 00147449 (Woodruff, Richard 2008-12-01 14:18:11 -0800 295) * cpu which runs the tick timer next, which might be
> 00147449 (Woodruff, Richard 2008-12-01 14:18:11 -0800 296) * this cpu as well. If we don't drop this here the
> 00147449 (Woodruff, Richard 2008-12-01 14:18:11 -0800 297) * jiffies might be stale and do_timer() never
> 00147449 (Woodruff, Richard 2008-12-01 14:18:11 -0800 298) * invoked.
> 00147449 (Woodruff, Richard 2008-12-01 14:18:11 -0800 299) */
> 00147449 (Woodruff, Richard 2008-12-01 14:18:11 -0800 300) if (cpu == tick_do_timer_cpu)
> 00147449 (Woodruff, Richard 2008-12-01 14:18:11 -0800 301) tick_do_timer_cpu = TICK_DO_TIMER_NONE;
> 00147449 (Woodruff, Richard 2008-12-01 14:18:11 -0800 302)
> 6ba9b346 (Ingo Molnar 2007-02-19 18:11:56 +0000 303) if (delta_jiffies > 1)
> 00147449 (Woodruff, Richard 2008-12-01 14:18:11 -0800 304)
> 00147449 (Woodruff, Richard 2008-12-01 14:18:11 -0800 305) /* Skip reprogram of event if its not changed */
> 00147449 (Woodruff, Richard 2008-12-01 14:18:11 -0800 306) if (ts->tick_stopped && ktime_equal(expires, dev->next_event))
> 00147449 (Woodruff, Richard 2008-12-01 14:18:11 -0800 307) goto out;
> 00147449 (Woodruff, Richard 2008-12-01 14:18:11 -0800 308)
> 6a7b3dc3 (Rusty Russell 2008-11-25 02:35:04 +1030 309) cpumask_set_cpu(cpu, nohz_cpu_mask);
>
> I've Cc'd both interested parties.
purely my fault. I've zapped that conflict resolution and picked up yours.
Ingo
^ permalink raw reply [flat|nested] 2+ messages in thread
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