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<base href="https://bugs.freedesktop.org/">
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<body><table border="1" cellspacing="0" cellpadding="8">
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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - Mesa CANNOT use libpthread-stubs"
href="https://bugs.freedesktop.org/show_bug.cgi?id=98048">98048</a>
</td>
</tr>
<tr>
<th>Summary</th>
<td>Mesa CANNOT use libpthread-stubs
</td>
</tr>
<tr>
<th>Product</th>
<td>Mesa
</td>
</tr>
<tr>
<th>Version</th>
<td>git
</td>
</tr>
<tr>
<th>Hardware</th>
<td>Other
</td>
</tr>
<tr>
<th>OS</th>
<td>All
</td>
</tr>
<tr>
<th>Status</th>
<td>NEW
</td>
</tr>
<tr>
<th>Severity</th>
<td>normal
</td>
</tr>
<tr>
<th>Priority</th>
<td>medium
</td>
</tr>
<tr>
<th>Component</th>
<td>Mesa core
</td>
</tr>
<tr>
<th>Assignee</th>
<td>mesa-dev@lists.freedesktop.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>idr@freedesktop.org
</td>
</tr>
<tr>
<th>QA Contact</th>
<td>mesa-dev@lists.freedesktop.org
</td>
</tr></table>
<p>
<div>
<pre>At least as far back as ecaa81b, Mesa has used pthread_mutexattr_init and
pthread_mutexattr_settype. Neither of these functions is available in libc6,
so both are supplied by libpthread-stubs. However, the implementations in
libpthread-stubs don't do anything. That's a huge problem because
pthread_mutex_init expects that pthread_mutexattr_t to contain valid data.
I have observed two adverse affects of this in piglit runs on multiple systems.
1. On softpipe, there are numerous sporadic crashes inside malloc or free (see
file:///home/idr/devel/graphics/piglit-results/results/problems.html). There
are also numerous valgrind warnings like:
==27195== Conditional jump or move depends on uninitialised value(s)
==27195== at 0x99E82A2: pthread_mutex_init (in
/usr/lib64/libpthread-2.22.so)
==27195== by 0xBA9EA1D: mtx_init (threads_posix.h:217)
==27195== by 0xBA9EA1D: _mesa_alloc_shared_state (shared.c:122)
==27195== by 0xB9DA749: _mesa_initialize_context (context.c:1188)
==27195== by 0xBB4478F: st_create_context (st_context.c:544)
==27195== by 0xBB6C64D: st_api_create_context (st_manager.c:669)
==27195== by 0xBCA6DD6: dri_create_context (dri_context.c:123)
==27195== by 0xBCA63EE: driCreateContextAttribs (dri_util.c:448)
==27195== by 0x52515E8: drisw_create_context_attribs (drisw_glx.c:476)
==27195== by 0x522B5A2: glXCreateContextAttribsARB (create_context.c:78)
==27195== by 0x6413353: ??? (in /usr/lib64/libwaffle-1.so.0.5.0)
==27195== by 0x640F394: waffle_context_create (in
/usr/lib64/libwaffle-1.so.0.5.0)
==27195== by 0x4F72238: make_context_current_singlepass
(piglit_wfl_framework.c:476)
2. On NV20 I have observed semi-random deadlocks from within meta. I have a
patch to work around these, but I now believe the real problem is the context
shared texture mutex is not being created PTHREAD_MUTEX_RECURSIVE because
pthread_mutexattr_settype does nothing.
piglit tests link with libpthread. I have confirmed that the versions from
libpthread-stubs are still called from within Mesa:
[idr@dynamic104 piglit]$ LIBGL_ALWAYS_SOFTWARE=y gdb --args bin/asmparsertest
ARBvp1.0 tests/asmparsertest/shaders/ARBvp1.0/sne-02.txt -auto -fbo
GNU gdb (GDB) Fedora 7.10.1-31.fc23
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For help, type "help".
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Reading symbols from bin/asmparsertest...done.
(gdb) b pthread_mutexattr_init
Function "pthread_mutexattr_init" not defined.
Make breakpoint pending on future shared library load? (y or [n]) y
Breakpoint 1 (pthread_mutexattr_init) pending.
(gdb) r
Starting program: /home/idr/devel/graphics/piglit/bin/asmparsertest ARBvp1.0
/home/idr/devel/graphics/piglit/tests/asmparsertest/shaders/ARBvp1.0/sne-02.txt
-auto -fbo
Missing separate debuginfos, use: dnf debuginfo-install
glibc-2.22-18.fc23.x86_64
warning: Unable to find libthread_db matching inferior's thread library, thread
debugging will not be available.
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib64/libthread_db.so.1".
couldn't open libtxc_dxtn.so, software DXTn compression/decompression
unavailable
Breakpoint 1, __pthread_zero_stub () at stubs.c:203
203 }
(gdb) bt
#0 __pthread_zero_stub () at stubs.c:203
#1 0x00007ffff0fb6a06 in mtx_init (type=4, mtx=0x6fb9d8) at
../../include/c11/threads_posix.h:215
#2 _mesa_alloc_shared_state (ctx=ctx@entry=0x7ffff7fd0010) at
main/shared.c:122
#3 0x00007ffff0ef274a in _mesa_initialize_context
(ctx=ctx@entry=0x7ffff7fd0010, api=api@entry=API_OPENGL_COMPAT,
visual=visual@entry=0x7fffffffd140, share_list=share_list@entry=0x0,
driverFunctions=driverFunctions@entry=0x7fffffffcbe0) at main/context.c:1188
#4 0x00007ffff105c790 in st_create_context (api=api@entry=API_OPENGL_COMPAT,
pipe=pipe@entry=0x63a2e0, visual=visual@entry=0x7fffffffd140,
share=share@entry=0x0, options=options@entry=0x7fffffffd278) at
state_tracker/st_context.c:544
#5 0x00007ffff108464e in st_api_create_context (stapi=<optimized out>,
smapi=0x62ad00, attribs=0x7fffffffd250, error=0x7fffffffd24c,
shared_stctxi=0x0) at state_tracker/st_manager.c:669
#6 0x00007ffff11bedd7 in dri_create_context (api=<optimized out>,
visual=0x62f870, cPriv=<optimized out>, major_version=<optimized out>,
minor_version=<optimized out>, flags=<optimized out>, notify_reset=false,
error=0x7fffffffd3fc, sharedContextPrivate=0x0) at dri_context.c:123
#7 0x00007ffff11be3ef in driCreateContextAttribs (screen=0x62ac60,
api=<optimized out>, config=<optimized out>, shared=<optimized out>,
num_attribs=<optimized out>, attribs=<optimized out>, error=0x7fffffffd3fc,
data=0x623070) at dri_util.c:448
#8 0x00007ffff77d05e9 in drisw_create_context_attribs (base=0x622f70,
config_base=0x637040, shareList=<optimized out>, num_attribs=<optimized out>,
attribs=<optimized out>, error=0x7fffffffd3fc) at drisw_glx.c:476
#9 0x00007ffff77aa5a3 in glXCreateContextAttribsARB (dpy=0x615390,
config=0x637040, share_context=0x0, direct=1, attrib_list=0x7fffffffd450) at
create_context.c:78
#10 0x00007ffff65fc354 in glx_context_create () from /lib64/libwaffle-1.so.0
#11 0x00007ffff65f8395 in waffle_context_create () from /lib64/libwaffle-1.so.0
#12 0x00007ffff7b3c239 in make_context_current_singlepass (wfl_fw=0x614c40,
test_config=0x7fffffffdb50, flavor=CONTEXT_GL_COMPAT,
partial_config_attrib_list=0x0) at
tests/util/piglit-framework-gl/piglit_wfl_framework.c:476
#13 0x00007ffff7b3c4f1 in make_context_current (wfl_fw=0x614c40,
test_config=0x7fffffffdb50, partial_config_attrib_list=0x0) at
tests/util/piglit-framework-gl/piglit_wfl_framework.c:557
#14 0x00007ffff7b3c5ea in piglit_wfl_framework_init (wfl_fw=0x614c40,
test_config=0x7fffffffdb50, platform=19, partial_config_attrib_list=0x0) at
tests/util/piglit-framework-gl/piglit_wfl_framework.c:613
#15 0x00007ffff7b3b1ae in piglit_fbo_framework_create
(test_config=0x7fffffffdb50) at
tests/util/piglit-framework-gl/piglit_fbo_framework.c:151
#16 0x00007ffff7b216e2 in piglit_gl_framework_factory
(test_config=0x7fffffffdb50) at
tests/util/piglit-framework-gl/piglit_gl_framework.c:48
#17 0x00007ffff7b2125d in piglit_gl_test_run (argc=3, argv=0x7fffffffdc88,
config=0x7fffffffdb50) at tests/util/piglit-framework-gl.c:191
#18 0x000000000040127e in main (argc=3, argv=0x7fffffffdc88) at
tests/asmparsertest/asmparsertest.c:41</pre>
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