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    SubjectRe: [PATCH 2/2] x86 platform driver: intelligent power sharing driver
    On Mon, May 10, 2010 at 10:00:46PM -0400, Andrew Morton wrote:
    > > + int i;
    > > + u16 avg;
    > > +
    > > + for (i = 0; i < IPS_SAMPLE_COUNT; i++)
    > > + total += (u64)(array[i] * 100);
    >
    > Actually, that does work. Somehow the compiler will promote array[i]
    > to u64 _before_ doing the multiplication. I think. Still, it looks
    > like a deliberate attempt to trick the compiler into doing a
    > multiplicative overflow ;)

    It seems to promote to int, probably due to the implicit type of
    "100". Aind since array is u16, * 100 can't overflow int. So yes, it's
    safe, but it does catch the eye as potentially unsafe.

    > > + cur_seqno = (thm_readl(THM_ITV) & ITV_ME_SEQNO_MASK) >>
    > > + ITV_ME_SEQNO_SHIFT;
    > > + if (cur_seqno == last_seqno &&
    > > + time_after(jiffies, seqno_timestamp + HZ)) {
    > > + dev_warn(&ips->dev->dev, "ME failed to update for more than 1s, likely hung\n");
    > > + } else {
    > > + seqno_timestamp = get_jiffies_64();
    > > + last_seqno = cur_seqno;
    > > + }
    > > +
    > > + last_msecs = jiffies_to_msecs(jiffies);

    Once it triggers, this will print the "likely hung" message every second
    until the end of time, won't it?

    -andy


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