Messages in this thread | | | Date | Thu, 13 Jul 2006 10:02:17 -0700 | From | Zachary Amsden <> | Subject | Re: [PATCH] next_timer_interrupt: simpler overflow handling |
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Keir Fraser wrote: > Having seen the patch applied to 2.6.17 to fix the overflowing > comparison in next_timer_interrupt() it occurred to me that a much > simpler fix is to not set hr_expires to MAX_JIFFY_OFFSET. It's way > further out from jiffies than necessary, which is why it's caused > problems. I instead propose that we initialise it to LONG_MAX>>1, just > as we already do for the non-hr expires variable. This will allow safe > comparison with any timer value in the range jiffies+/-(LONG_MAX>>1) > which is plenty of range around jiffies (+/- 12 days if HZ=1000 and > long is 32 bits). > > The advantages are simpler code, and uniform initialisation of expires > and hr_expires variables.
Even simpler would be to just make MAX_JIFFY_OFFSET be (LONG_MAX >> 1) and use this for both. In fact, it appears it used to be, judging by the comment in jiffies.h:
* The maximum jiffie value is (MAX_INT >> 1). Here we translate that
But seeing as this could have unanticipated side effects, I like this fix better.
Acked-By: Zachary Amsden <zach@vmware.com> - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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