At 1:00 PM -0700 2001-07-23, Linus Torvalds wrote:
>On Mon, 23 Jul 2001, Andrea Arcangeli wrote:
>> gcc can assume 'state' stays constant in memory not just during the
>The point is that if the kernel has _any_ algorithm where it cares, it's a
>kernel bug. With volatile or without.
>SHOW ME THE CASE WHERE IT CARES. Let's fix it. Let's not just hide it with
>static int __init timer_irq_works(void)
> unsigned int t1 = jiffies;
> /* Let ten ticks pass... */
> mdelay((10 * 1000) / HZ);
> * Expect a few ticks at least, to be sure some possible
> * glue logic does not lock up after one or two first
> * ticks in a non-ExtINT mode. Also the local APIC
> * might have cached one ExtINT interrupt. Finally, at
> * least one tick may be lost due to delays.
> if (jiffies - t1 > 4)
> return 1;
> return 0;
If jiffies were not volatile, this initializing assignment and the
test at the end could be optimized away, leaving an unconditional
"return 0". A lock is of no help.
-- /Jonathan Lundell. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to email@example.com More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
This archive was generated by hypermail 2b29 : Mon Jul 23 2001 - 21:00:17 EST