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From: David Miller <davem@davemloft.net>
To: mtk.manpages@googlemail.com
Cc: akpm@linux-foundation.org, lkml@davidb.org, paulus@samba.org,
	drepper@redhat.com, cfriesen@nortel.com, schwab@suse.de,
	linux-kernel@vger.kernel.org
Subject: Re: compat_sys_times() bogus until jiffies >= 0.
Date: Thu, 20 Dec 2007 03:51:04 -0800 (PST)	[thread overview]
Message-ID: <20071220.035104.240386115.davem@davemloft.net> (raw)
In-Reply-To: <476A53D4.7040909@gmail.com>

From: Michael Kerrisk <mtk.manpages@googlemail.com>
Date: Thu, 20 Dec 2007 12:36:52 +0100

> Some testing just now shows me that lseek() on /dev/mem suffers similar
> problems when seeking to bytes 0xfffff001 through to 0xffffffff.

Only on x86 platforms.  Sparc, IA64, MIPS, powerpc, etc. all get this
case right.

Yes it's another unfortunate side effect of how error status is
indicated for x86 system calls.

I would suggest, that we put something in place to fix this
in the long term:

1) Start setting the condition codes properly to indicate
   error in the system call return path on x86 like other
   platforms do now.  Make sure that it tips off on
   force_successful_syscall_return(), as needed.

2) Come up with a transition plan for glibc et al. to take
   advantage of this.

It actually sounds like the kind of problem that could be
solved well using the VDSO page. :-)


  reply	other threads:[~2007-12-20 11:51 UTC|newest]

Thread overview: 37+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2007-11-07 22:47 compat_sys_times() bogus until jiffies >= 0 David Brown
2007-11-07 23:28 ` Andrew Morton
2007-11-08  0:18   ` Andrew Morton
2007-11-08  0:54     ` Andreas Schwab
2007-11-08  1:17       ` Andrew Morton
2007-11-08  1:53     ` Paul Mackerras
2007-11-08  2:09       ` David Miller
2007-11-08 10:20         ` Andreas Schwab
2007-11-08 14:42           ` Chris Friesen
2007-11-09 18:20             ` Ulrich Drepper
2007-12-20 11:36               ` Michael Kerrisk
2007-12-20 11:51                 ` David Miller [this message]
2007-12-22  0:42                   ` Andi Kleen
2007-12-22  1:41                     ` David Miller
2007-12-22  1:45                       ` David Miller
2007-12-22  1:53                         ` Andi Kleen
2007-12-22  4:36                           ` David Miller
2007-12-22 12:47                             ` Andi Kleen
2007-12-22  1:49                       ` Andi Kleen
2007-11-08 19:25         ` Denys Vlasenko
2007-11-08  3:07       ` Andrew Morton
2007-11-08  3:13         ` David Miller
2007-11-08  5:15           ` Paul Mackerras
2007-11-08  6:24             ` David Miller
2007-11-08  4:59         ` Paul Mackerras
2007-11-08  5:20           ` Andrew Morton
2007-11-08  5:36             ` Paul Mackerras
2007-11-08  6:12               ` Andrew Morton
2007-11-08  6:25             ` David Miller
2007-11-08  7:09               ` Andrew Morton
2007-11-08  7:14                 ` David Miller
2007-11-08  8:53               ` Paul Mackerras
2007-11-08  6:22           ` David Miller
2007-11-08 19:27         ` Denys Vlasenko
2007-11-08  0:50   ` David Miller
2007-11-08  1:13     ` Andrew Morton
2007-11-08  6:00   ` David Brown

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