Subject: Re: TCP problems - maybe a solution?
To: David Laight <firstname.lastname@example.org>
From: Jaromir Dolecek <email@example.com>
Date: 07/22/2002 14:47:44
I looked at this too. The callout_deactivate() is called
within the invoked callout routine. AFAIK it's only to ensure
that 'unarmed' timeouts are marked as inactive too, to get easy
way to determine whether or not a timeout is 'armed' or 'executing'.
Callout is always one time thing, i.e. only ever called once. It
must be callout_reset() to launch it again. Note that most tcp
timeout routines eventually do call TCP_TIMER_ARM() and thus
callout_reset(), unless some serious network problem is detected.
The callout_deactivate() calls seem to be right IMHO.
David Laight wrote:
> I've just found what looks like a bug in the TCP timeout code.
> (This is from reading the sources!)
> The 'dubious' code is in rev 1.53 of tcp_timer.c (10 Sep 2001),
> I don't know which release that refers to.
> The TCP code was changed to use kernel callouts (instead of
> traversing the world twice a second) - a not unreasonable change.
> However the code calls 'callout_deactivate()' in order (I presume)
> to stop the timeout. However callout_deactivate is:
> #define callout_deactivate(c) ((c)->c_flags &= ~CALLOUT_ACTIVE)
> and, unless i'm misreading the code, the CALLOUT_ACTIVE flag
> has absolutely no effect on the callout routines.
> I suspect this should be callout_stop() - but maybe something
> more subtle was intended.
> David Laight: firstname.lastname@example.org
Jaromir Dolecek <jdolecek@NetBSD.org> http://www.NetBSD.org/Ports/i386/ps2.html
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