Messages in this thread | | | Date | Fri, 7 Mar 2003 04:15:58 -0800 | From | Andrew Morton <> | Subject | Re: 2.5.64 and jiffies wrap |
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Jens Axboe <axboe@suse.de> wrote: > > Hi, > > The patch doesn't look right, why is INITIAL_JIFFIES being cast to > unsigned int? This breaks x86_64 at least. > > ... > -#define INITIAL_JIFFIES ((unsigned int) (-300*HZ))
This sets the initial jiffies value to 0x00000000fffb6c20, which can trigger 32-bit wraparound bugs: if some random jiffy counter wraps from 0x00000000ffffffff to 0x0000000000000000 then things fail.
davem was bitten by at least one such bug in the qlogicfc driver. It would have caused 64-bit machines to fail after 49 days.
It turns out that it is more valuable to test for this than to test for 64-bit wraparound bugs. - 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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