callout_drain either broken or man page needs updating

[Matthew Macy]

 ---- On Fri, 15 Jul 2016 01:43:03 -0700 Gleb Smirnoff <glebius at FreeBSD.org> wrote ---- 
 > On Thu, Jul 14, 2016 at 10:14:46PM -0700, Matthew Macy wrote: 
 > M>  > On 07/15/16 05:45, Matthew Macy wrote:  
 > M>  > > glebius last commit needs some further re-work.  
 > M>  >   
 > M>  > Glebius commit needs to be backed out, at least the API change that   
 > M>  > changes the return value when calling callout_stop() when the callout is   
 > M>  > scheduled and being serviced. Simply because there is code out there,   
 > M>  > like Mattew and others have discovered that is "refcounting" on the   
 > M>  > callout_reset() and expecting that a subsequent callout_stop() will   
 > M>  > return 1 to "unref".  
 > M>  
 > M> Yes. This is the cause of the "refcnt 0 on LLE at boot..." regression. 

I misread his comment on the reason for the failure. But, the failure is caused by a regression in callout_stop.

 > No it isn't. The regression is caused by unintentional change of return 
 > value for never scheduled callout. The fix is now being tested, see PR 210884. 

Thanks. Let me know when I can update.
-M