From owner-svn-src-head@FreeBSD.ORG  Mon Feb  9 20:34:40 2015
Return-Path: <owner-svn-src-head@FreeBSD.ORG>
Delivered-To: svn-src-head@freebsd.org
Received: from mx1.freebsd.org (mx1.freebsd.org
 [IPv6:2001:1900:2254:206a::19:1])
 (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits))
 (No client certificate requested)
 by hub.freebsd.org (Postfix) with ESMTPS id 0D9F57E1;
 Mon,  9 Feb 2015 20:34:40 +0000 (UTC)
Received: from bigwig.baldwin.cx (bigwig.baldwin.cx [IPv6:2001:470:1f11:75::1])
 (using TLSv1 with cipher DHE-RSA-CAMELLIA256-SHA (256/256 bits))
 (Client did not present a certificate)
 by mx1.freebsd.org (Postfix) with ESMTPS id DBD10AD9;
 Mon,  9 Feb 2015 20:34:39 +0000 (UTC)
Received: from ralph.baldwin.cx (pool-173-54-116-245.nwrknj.fios.verizon.net
 [173.54.116.245])
 by bigwig.baldwin.cx (Postfix) with ESMTPSA id 92AA5B97B;
 Mon,  9 Feb 2015 15:34:38 -0500 (EST)
From: John Baldwin <jhb@freebsd.org>
To: Randall Stewart <rrs@freebsd.org>
Subject: Re: svn commit: r278469 - in head/sys: kern sys
Date: Mon, 09 Feb 2015 15:09:46 -0500
Message-ID: <1619204.FQlXD7hmMU@ralph.baldwin.cx>
User-Agent: KMail/4.14.2 (FreeBSD/10.1-STABLE; KDE/4.14.2; amd64; ; )
In-Reply-To: <201502091919.t19JJjbg061542@svn.freebsd.org>
References: <201502091919.t19JJjbg061542@svn.freebsd.org>
MIME-Version: 1.0
Content-Transfer-Encoding: 7Bit
Content-Type: text/plain; charset="us-ascii"
X-Greylist: Sender succeeded SMTP AUTH, not delayed by milter-greylist-4.2.7
 (bigwig.baldwin.cx); Mon, 09 Feb 2015 15:34:38 -0500 (EST)
Cc: svn-src-head@freebsd.org, svn-src-all@freebsd.org,
 src-committers@freebsd.org
X-BeenThere: svn-src-head@freebsd.org
X-Mailman-Version: 2.1.18-1
Precedence: list
List-Id: SVN commit messages for the src tree for head/-current
 <svn-src-head.freebsd.org>
List-Unsubscribe: <http://lists.freebsd.org/mailman/options/svn-src-head>,
 <mailto:svn-src-head-request@freebsd.org?subject=unsubscribe>
List-Archive: <http://lists.freebsd.org/pipermail/svn-src-head/>
List-Post: <mailto:svn-src-head@freebsd.org>
List-Help: <mailto:svn-src-head-request@freebsd.org?subject=help>
List-Subscribe: <http://lists.freebsd.org/mailman/listinfo/svn-src-head>,
 <mailto:svn-src-head-request@freebsd.org?subject=subscribe>
X-List-Received-Date: Mon, 09 Feb 2015 20:34:40 -0000

On Monday, February 09, 2015 07:19:45 PM Randall Stewart wrote:
> Author: rrs
> Date: Mon Feb  9 19:19:44 2015
> New Revision: 278469
> URL: https://svnweb.freebsd.org/changeset/base/278469
> 
> Log:
>   This fixes two conditions that can incur when migration
>   is being done in the callout code and harmonizes the macro
>   use.:
>   1) The callout_active() will lie. Basically if a migration
>      is occuring and the callout is about to expire and the
>      migration has been deferred, the callout_active will no
>      longer return true until after the migration. This confuses
>      and breaks callers that are doing callout_init(&c, 1); such
>      as TCP.
>   2) The migration code had a bug in it where when migrating, if
>      a two calls to callout_reset came in and they both collided with
>      the callout on the wheel about to run, then the second call to
>      callout_reset would corrupt the list the callout wheel uses
>      putting the callout thread into a endless loop.
>   3) Per imp, I have fixed all the macro occurance in the code that
>      were for the most part being ignored.
> 
>   Phabricator D1711 and looked at by lstewart and jhb and sbruno.
>   Reviewed by:	kostikbel, imp, adrian, hselasky
>   MFC after:	3 days
>   Sponsored by:	Netflix Inc.

Thank you guys for working together to fix the migration race in a way
that lets CALLOUT_MPSAFE timers use multiple CPUs still.

I do think that callout_drain_async() would also be useful to add.

-- 
John Baldwin