Re: [Patch] Re: Nasty suprise with uptime

george anzinger
2001-11-01T11:22:40Z

Tim Schmielau wrote:
~snip
> @@ -683,6 +683,34 @@
> if (TQ_ACTIVE(tq_timer))
> mark_bh(TQUEUE_BH);
> }
> +
> +
> +#if BITS_PER_LONG < 48
> +
> +u64 get_jiffies64(void)
> +{
> + static unsigned long jiffies_hi = 0;
> + static unsigned long jiffies_last = INITIAL_JIFFIES;
> + unsigned long jiffies_tmp;
> +
> + jiffies_tmp = jiffies; /* avoid races */
> + if (jiffies_tmp < jiffies_last) /* We have a wrap */
> + jiffies_hi++;
> + jiffies_last = jiffies_tmp;
> +
> + return (jiffies_tmp | ((u64)jiffies_hi) << BITS_PER_LONG);

Doesn't this need to be protected on SMP machines? What if two cpus
call get_jiffies64() at the same time... Seems like jiffies_hi could
get bumped twice instead of once.

George