Re: musl pthread/tls issue.

[Timo Teras <timo.teras@iki.fi>]

On Wed, 22 Oct 2014 14:33:01 +0800
黄建忠 <jianzhong.huang@i-soft.com.cn> wrote:

> Hi, Rich and all.
> 
> These days, I finished build a bootable x86_64 system(rpm based)
> include musl/systemd/dracut/gcc-4.9.1/gcc-5/clang-3.5 and
> wayland/Xorg and the whole GNOME-3.14 desktop(except webkit js
> segfault issue I mentioned before) with a lot of patches(I will
> release all of them someday until it reach a stable state.)
> 
> After a simple try, I found gnome-shell will segfault If I triggered
> the app list(not always but often).
> 
> The dmesg report "pool [<some pid>] segfault xxxxxxxxxxx
> libpixman-xxxxx", That's to say, it segfault in pixman library(A
> common library used by Xorg and cairo),
> gdb report it's a thread issue(a thread of gnome-shell) and segfault
> at the beginning of general_composite_rect function in
> pixman-general.c, the pointer of argument can not be accessed.
> 
> And after a quick look, the problem is in pixman-compiler.h, it
> defined TLS related codes and macros according to specific
> implementation(win32/mingw/pthread and so on).
> By default, the TLS codes will be compiled, if it was disabled, there
> is still a pthread fallback use 'pthread_key_create' and other
> pthread funcs.
> 
> Here is the link to it:
> http://cgit.freedesktop.org/pixman/tree/pixman/pixman-compiler.h,
> please look at the TLS section.
> 
> That's to say, there must be a problem exist in musl pthread/tls
> implementation and can be triggered under certain circumstances.
> Please help to solve it.
> 
> Related components:
> Kernel: linux-3.17.0 without patch.
> binutils: 2.24.90 without patch.
> Compiler: gcc-5 and clang-3.5. with musl-enable patch.
> Pixman: 0.32.6 git
> Cairo: 1.14.0
> Mesa: 10.3.1 stable
> Xorg: 1.16.1 stable
> gnome: 3.14 stable

Is it perhaps this:
https://bugs.freedesktop.org/show_bug.cgi?id=35268

Does preloading libGL.so help?

We do this as workaround for eg. firefox currently (in Alpine Linux):
http://git.alpinelinux.org/cgit/aports/commit/?id=d9cda70e2c149004f1e87edd1de8f6e332e76953

/Timo