Here is a fix for the problem that eliminates the index from the 
structure.  The index ALWAYS depends on the current value of 
base->timer_jiffies in a rather simple way which is I exploit.  Either 
patch works, but this seems much simpler...

-g


Tim Schmielau wrote:
> On Tue, 18 Mar 2003, Tim Schmielau wrote:
> 
> 
>>Please don't yet forward to Linus. After twisting my little brain a bit
>>further, I see that the patch is still wrong if the lowest TVR_BITS of
>>INITIAL_JIFFIES happen to be zero while others are not.
> 
> 
> OK, this one looks ugly but should be correct, even in the case of a
> partial timer cascade on the first timer interrupt:
> 
> 
> --- linux-2.5.65/kernel/timer.c.orig	Tue Mar 18 13:02:39 2003
> +++ linux-2.5.65/kernel/timer.c	Tue Mar 18 13:41:53 2003
> @@ -1182,11 +1182,23 @@
>  		INIT_LIST_HEAD(base->tv1.vec + j);
> 
>  	base->timer_jiffies = INITIAL_JIFFIES;
> -	base->tv1.index = INITIAL_JIFFIES & TVR_MASK;
> -	base->tv2.index = (INITIAL_JIFFIES >> TVR_BITS) & TVN_MASK;
> -	base->tv3.index = (INITIAL_JIFFIES >> (TVR_BITS+TVN_BITS)) & TVN_MASK;
> -	base->tv4.index = (INITIAL_JIFFIES >> (TVR_BITS+2*TVN_BITS)) & TVN_MASK;
> -	base->tv5.index = (INITIAL_JIFFIES >> (TVR_BITS+3*TVN_BITS)) & TVN_MASK;
> +	/*
> +	 * The tv indices are always larger by one compared to the
> +	 * respective parts of timer_jiffies. If all lower indices are
> +	 * zero at initialisation, this is achieved by an (otherwise
> +	 * unneccessary) invocation of the timer cascade on the first
> +	 * timer interrupt. If not, we need to take it into account
> +	 * here:
> +	 */
> +	j  = (base->tv1.index = INITIAL_JIFFIES & TVR_MASK) !=0;
> +	j |= (base->tv2.index = ((INITIAL_JIFFIES >> TVR_BITS) + j)
> +	                        & TVN_MASK) !=0;
> +	j |= (base->tv3.index = ((INITIAL_JIFFIES >> (TVR_BITS+TVN_BITS)) + j)
> +	                        & TVN_MASK) !=0;
> +	j |= (base->tv4.index = ((INITIAL_JIFFIES >> (TVR_BITS+2*TVN_BITS)) + j)
> +	                        & TVN_MASK) !=0;
> +	      base->tv5.index = ((INITIAL_JIFFIES >> (TVR_BITS+3*TVN_BITS)) + j)
> +	                        & TVN_MASK;
>  }
> 
>  static int __devinit timer_cpu_notify(struct notifier_block *self,
> 
> -
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-- 
George Anzinger   george@mvista.com
High-res-timers:  http://sourceforge.net/projects/high-res-timers/
Preemption patch: http://www.kernel.org/pub/linux/kernel/people/rml