bug in useldt.h

[Felipe Contreras]

Hi,

I've tracked down a problem that arises when compiling glibc with the
--enable-kernel option.

I'm almost sure the problem is in the code of this file:
glibc-2.2.4/linuxthreads/sysdeps/i386/useldt.h

And generates a problem like the one stated here:
http://mail.gnu.org/pipermail/bug-glibc/2001-March/002753.html

On my old system I got the some programs linked to libpthreads
segfaulting, but where only a few and recompiling glibc changing the
CFLAGS from "-O3 -march=i686" to "-O2 -march=i686" the problem was gone.
The could trace the segfault to __pthread_alt_lock().

Now on my new system I get something similar when building
fileutils-4.1, it makes "ls" segfault. I looked for the libraries and I
saw that the segfault came only when the programs where linked to
"librt" and "libpthreads". I traced the segfault and again was in
__pthread_alt_lock().

I tryied to compile glibc again and again in my new system and I noticed
something very strange... sometimes it worked. I tryied exactly the same
options.

Withouth --enable-kernel make the problem go, and someone did a patch so
only useldt.h is discarded:
http://archive.linuxfromscratch.org/mail-archives/lfs-dev/2001/10/0589.html

So I think there is no doubt, the code in useldt.h needs a deep
revision.

Felipe Contreras