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From: "Werner Tuchan" <tuwn@gmx.net>
To: rth@gcc.gnu.org
Cc: gcc-prs@gcc.gnu.org,
Subject: Re: libstdc++/5198: 3.0.3 linux x m68k build fail: invalid opcodes in c++locale.cc
Date: Mon, 04 Feb 2002 11:06:00 -0000	[thread overview]
Message-ID: <20020204190614.4138.qmail@sources.redhat.com> (raw)

The following reply was made to PR libstdc++/5198; it has been noted by GNATS.

From: "Werner Tuchan" <tuwn@gmx.net>
To: <rodrigc@gcc.gnu.org>,
	<gcc-bugs@gcc.gnu.org>,
	<gcc-prs@gcc.gnu.org>,
	<gcc-gnats@gcc.gnu.org>
Cc:  
Subject: Re: libstdc++/5198: 3.0.3 linux x m68k build fail: invalid opcodes in c++locale.cc
Date: Mon, 4 Feb 2002 11:35:05 +0100

 I think the solution for the 68000, 68010, cpu32 & 5400 CPUs useing the TAS
 instruction is really dangerous since it may easily deadlock. A low priority
 thread can enter the critical section and may be preempted by a high priorty
 thread which enters the TAS loop and stays there forever consuming all CPU
 cycles so that the low priorty thread has no chance to release the lock.
 
 Therefore spinlock implementations usually disable preemption before trying
 to acquire the lock. Actually busy loop spinlocks are only usefull on SMP
 machines anyway. I would recommend that we disable interrupts for the latter
 CPUs in addition to the TAS instruction.
 
 -Werner
 
 http://gcc.gnu.org/cgi-bin/gnatsweb.pl?cmd=view%20audit-trail&database=gcc&p
 r=5198
 
 
 
 
 
 


             reply	other threads:[~2002-02-04 19:06 UTC|newest]

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2002-02-04 11:06 Werner Tuchan [this message]
  -- strict thread matches above, loose matches on Subject: below --
2002-02-05  5:26 Werner Tuchan
2002-02-04 14:36 Aaron J. Grier
2002-01-23 17:41 rth
2002-01-08 13:56 Aaron J. Grier
2002-01-04 15:36 Aaron J. Grier
2002-01-04 14:46 Craig Rodrigues
2002-01-04 14:36 Aaron J. Grier
2002-01-04 14:26 Craig Rodrigues
2002-01-04 13:56 Don Lindsay
2002-01-04 12:56 Craig Rodrigues
2002-01-04 12:26 Don Lindsay
2002-01-03 20:46 Craig Rodrigues
2002-01-03 20:16 Don Lindsay
2002-01-03 16:12 rodrigc
2002-01-03 15:47 rodrigc
2001-12-26 16:56 Don Lindsay
2001-12-26 16:20 rodrigc
2001-12-26 14:36 lindsayd

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