From owner-cvs-all  Fri Mar  9 14:25:26 2001
Delivered-To: cvs-all@freebsd.org
Received: from cr66388-a.rchrd1.on.wave.home.com (cr66388-a.rchrd1.on.wave.home.com [24.114.165.24])
	by hub.freebsd.org (Postfix) with ESMTP
	id 5AA9437B719; Fri,  9 Mar 2001 14:25:22 -0800 (PST)
	(envelope-from jburkholder0829@home.com)
Received: from cr66388-a.rchrd1.on.wave.home.c (localhost [127.0.0.1])
	by cr66388-a.rchrd1.on.wave.home.com (Postfix) with ESMTP
	id E3527BA69; Fri,  9 Mar 2001 17:25:21 -0500 (EST)
X-Mailer: exmh version 2.3.1 01/18/2001 with nmh-1.0.4
To: John Baldwin <jhb@FreeBSD.org>
Cc: cvs-committers@FreeBSD.org, cvs-all@FreeBSD.org
Subject: Re: cvs commit: src/sys/alpha/include mutex.h src/sys/i386/include 
 mutex.h src/sys/ia64/include mutex.h src/sys/kern kern_mutex.c kern_fork.c 
 src/sys/sys proc.h
In-Reply-To: Message from John Baldwin <jhb@FreeBSD.org> 
   of "Thu, 08 Mar 2001 23:24:17 PST." <200103090724.f297OIk50706@freefall.freebsd.org> 
Mime-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Date: Fri, 09 Mar 2001 17:25:21 -0500
From: Jake Burkholder <jburkholder0829@home.com>
Message-Id: <20010309222521.E3527BA69@cr66388-a.rchrd1.on.wave.home.com>
Sender: owner-cvs-all@FreeBSD.ORG
Precedence: bulk
X-Loop: FreeBSD.ORG

> jhb         2001/03/08 23:24:17 PST
> 
>   Modified files:
>     sys/alpha/include    mutex.h 
>     sys/i386/include     mutex.h 
>     sys/ia64/include     mutex.h 
>     sys/kern             kern_mutex.c kern_fork.c 
>     sys/sys              proc.h 
>   Log:
>   Fix mtx_legal2block.  The only time that it is bad to block on a mutex is
>   if we hold a spin mutex, since we can trivially get into deadlocks if we
>   start switching out of processes that hold spinlocks.  Checking to see if
>   interrupts were disabled was a sort of cheap way of doing this since most
>   of the time interrupts were only disabled when holding a spin lock.  At
>   least on the i386.  To fix this properly, use a per-process counter
>   p_spinlocks that counts the number of spin locks currently held, and
>   instead of checking to see if interrupts are disabled in the witness code,
>   check to see if we hold any spin locks.  Since child processes always
>   start up with the sched lock magically held in fork_exit(), we initialize
>   p_spinlocks to 1 for child processes.  Note that proc0 doesn't go through
>   fork_exit(), so it starts with no spin locks held.
>   
>   Consulting from:	cp
>   
>   Revision  Changes    Path
>   1.21      +1 -3      src/sys/alpha/include/mutex.h
>   1.30      +0 -1      src/sys/i386/include/mutex.h
>   1.11      +1 -2      src/sys/ia64/include/mutex.h
>   1.57      +9 -3      src/sys/kern/kern_mutex.c
>   1.106     +5 -1      src/sys/kern/kern_fork.c
>   1.154     +2 -1      src/sys/sys/proc.h
> 

Cool!


To Unsubscribe: send mail to majordomo@FreeBSD.org
with "unsubscribe cvs-all" in the body of the message