linux-kernel - Re: [PATCH] prevent timespec/timeval to ktime

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Date:	Thu, 31 Aug 2006 00:08:36 +0200
From:	Frank v Waveren <fvw@....cx>
To:	Thomas Gleixner <tglx@...utronix.de>
Cc:	Andrew Morton <akpm@...l.org>, Ingo Molnar <mingo@...e.hu>,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] prevent timespec/timeval to ktime_t overflow

On Thu, Aug 31, 2006 at 12:05:02AM +0200, Thomas Gleixner wrote:
> > With this patch, we sleep shorter than specified, and don't signal
> > this in any way. Returning EINVAL for anything except negative tv_sec
> > or invalid tv_nsec breaks the spec too, but I prefer errors to
> > silently sleeping too short.
> 
> I really don't care whether we sleep 100 or 5000 years in the case of
> "sleep MAX_LONG"
Don't sell your patch short, it still manages nearly 300 years..

> > I'll grant this is more of an aesthetic point than something that'll
> > cause real-world problems (300 years is a long time for any sleep),
> > but if things break I like them to do so as loudly as possible, as a
> > general rule.
> 
> One thing you ignore is that your patch does not cure the introduced
> user space breakage, it just replaces the overflow caused very short
> sleep by a return -EINVAL, which is breaking existing userspace in a
> different way. We have to preserve user space interfaces even when they
> violate your aesthetic well-being.

The userspace interface gets broken either way. The error might
actually serve as a decent portability wake up call, solaris 64 bit
also silently overflows in nanosleep, and since I've only had the
opportunity to check on solaris and linux, I wouldn't be surprised if
other OSes had the same problem.

-- 
Frank v Waveren                                  Key fingerprint: BDD7 D61E
fvw@....cx                                              5D39 CF05 4BFC F57A
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