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Date: Sun, 15 Jul 2012 20:16:15 -0700
From: Reese Faucette <reese@myri.com>
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To: Sepherosa Ziehau <sepherosa@gmail.com>
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Cc: freebsd-net@freebsd.org
Subject: Re: question in tcp_do_segment()
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On 7/15/2012 6:53 PM, Sepherosa Ziehau wrote:
>> On 7/15/2012 3:26 AM, Sepherosa Ziehau wrote:
> Hmm, callout_active() is not used to check for whether the callout is
> fired or not; it is used to check whether callout_reset() has been
> called but callout_stop() is not yet been called.  IMO,
> callout_reset() is "set" the callout, callout_stop() is "unset" the
> callout.

OK, sorry, I was going by the callout implementation in 8.0 - I compared 
sources and the tcp_input code was roughly the same, tcp_timer_*() was 
roughly the same, but since all that was the same, I did not dig all the 
way to the bottom of callout_reset() implementation, and I see that the 
semantics of callout_active() have changed to be as you describe.  My 
callout_active() from 8.0 is:
#define callout_active(c)       ((c)->c_flags & CALLOUT_FIRED)
hence, my lame claims about the behavior.
Sorry for the noise...
-reese