From: "Russ Cox" <rsc@swtch.com>
To: 9fans@9fans.net
Subject: Re: [9fans] ilock funny?
Date: Thu, 29 May 2008 09:59:36 -0400 [thread overview]
Message-ID: <20080529135908.815F11E8C53@holo.morphisms.net> (raw)
In-Reply-To: <c15da790f17dd290f2a12308293e124f@quanstro.net>
> i can't see how this could be unless on very first
> reference of the lock there is a race with the looser
> evaluateing !l->isilock before that processor can see
> the winner setting l->isilock to 1.
>
> if this diagnosis is correct, what is the proper fix?
take the test out.
this is my fault. (ironically, i put it in while debugging
some of your code, years ago.)
change:
/*
* Cannot also check l->pc and l->m here because
* they might just not be set yet, or the lock might
* even have been let go.
*/
if(!l->isilock){
dumplockmem("ilock:", l);
panic("corrupt ilock %p pc=%luX m=%p isilock=%d",
l, l->pc, l->m, l->isilock);
}
to
/*
* Cannot also check l->pc, l->m, or l->isilock here
* because they might just not be set yet, or
* (for pc and m) the lock might have just been unlocked.
*/
two out of three isn't bad. ;-)
russ
next prev parent reply other threads:[~2008-05-29 13:59 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-05-29 1:34 erik quanstrom
2008-05-29 13:40 ` Gorka Guardiola
2008-05-29 14:01 ` erik quanstrom
2008-05-29 18:47 ` Gorka Guardiola
2008-05-29 13:59 ` Russ Cox [this message]
2008-05-29 14:00 ` erik quanstrom
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