Messages in this thread | | | Date | Thu, 13 Apr 2006 16:11:30 -0700 (PDT) | From | Linus Torvalds <> | Subject | Re: PROBLEM: pthread-safety bug in write(2) on Linux 2.6.x |
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On Thu, 13 Apr 2006, Linus Torvalds wrote:
> > > On Fri, 14 Apr 2006, Alan Cox wrote: > > > > Quality for whom ? There is a measurable cost to all that extra locking > > which will hurt everyone. Given existing kernels don't make the > > guarantee and SuS v3 does not make the guarantee the apps that need it > > will continue to do the extra work themselves anyway. > > True.
Side note: if you want the strange POSIX guarantees that Dan quoted (atomicity between write and fstat), you'd almost have to do it with user-space crapola magic locks. Doing it in the kernel would just be insane, you'd have to have some per-process "IO semaphore".
(Doing it in user space _also_ sounds insane, but then you could have a switch like "POSIX me harder, and do all the really stupid things" at compile time or something)
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