Re: [timer] max timeout

[Mark Frazer <mark@somanetworks.com>]

george anzinger <george@mvista.com> [01/05/25 17:04]:
> More than enough on the fp.  Now the other question.  
> 
> The time value is in jiffies (aka 1/Hz sec.).  The max value (in a 32
> bit system) is 0x7ffffff.  This value is added to the current value of
> jiffies to get the the absolute timer expire time.  While the value is
> unsigned (and thus you could go higher) the compare code (timer_before()
> and timer_after()) depend on the subtraction (of jiffies from expire) to
> be of the correct sign.  To insure this you must keep the timeout values
> sign clear (or if you don't like to think of an unsigned as having a
> sign, then the highest order bit must be zero).
> 
> George

The output of `find . -type f | xargs grep 'jiffies +'` would suggest
that there are a few latent bugs as jiffies grows to values near the
top of its range.  I guess this hasn't turned up as 0x7fffffff / (100 *
3600 * 24) = 248.55.