Jamie Lokier <[EMAIL PROTECTED]> wrote: > > Andrew Morton wrote: > > iirc we ended up deciding that the futex problems around that time were due > > to userspace problems (a version of libc). But then, there's no discussion > > around Seto's patch and it didn't get applied. So I don't know what > > happened to that work - it's all a bit mysterious. > > It can be fixed _either_ in Glibc, or by changing the kernel. > > That problem is caused by differing assumptions between Glibc and the > kernel about subtle futex semantics. Which goes to show they are > really clever, or something. > > I provided pseudo-code for the Glibc fix, but not an actual patch > because NPTL is quite complicated and I wanted to know the Glibc > people were interested, but apparently they were too busy at the time > - benchmarks would have made sense for such a patch. > > Scott Snyder started fixing part of Glibc, and that did fix his > instance of this problem so we know the approach works. But a full > patch for Glibc was not prepared. > > The most recent messages under "Futex queue_me/get_user ordering", > with a patch from Jakub Jelinek will fix this problem by changing the > kernel. Yes, you should apply Jakub's most recent patch, message-ID > "<[EMAIL PROTECTED]>". > > I have not tested the patch, but it looks convincing.
OK, thanks. Lee && Paul, that's at ftp://ftp.kernel.org/pub/linux/kernel/people/akpm/patches/2.6/2.6.12-rc1/2.6.12-rc1-mm1/broken-out/futex-queue_me-get_user-ordering-fix.patch > I argued for fixing Glibc on the grounds that the changed kernel > behaviour, or more exactly having Glibc depend on it, loses a certain > semantic property useful for unusual operations on multiple futexes at > the same time. But I appear to have lost the argument, and Jakub's > latest patch does clean up some cruft quite nicely, with no expected > performance hit. Futexes were initially so simple. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
