[Bug threads/9635] Cannot find new threads: generic error

[Bug threads/9635] Cannot find new threads: generic error

[john.carter at tait dot co.nz]

http://sourceware.org/bugzilla/show_bug.cgi?id=9635

--- Comment #2 from John Carter <john.carter at tait dot co.nz> 2011-05-27 05:26:52 UTC ---
Created attachment 5756
  --> http://sourceware.org/bugzilla/attachment.cgi?id=5756
Very short file that "kills gdb".

To compile and demonstrate the bug...
   gcc -O0 -g -pthread -o kill_gdb kill_gdb.c
/usr/bin/gdb ./kill_gdb 
GNU gdb (GDB) 7.2-ubuntu
Copyright (C) 2010 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.  Type "show copying"
and "show warranty" for details.
This GDB was configured as "i686-linux-gnu".
For bug reporting instructions, please see:
<http://www.gnu.org/software/gdb/bugs/>...
Reading symbols from /btrfs/johnc/tmp/kill_gdb...done.
(gdb) start
Temporary breakpoint 1 at 0x8048367: file kill_gdb.c, line 7.
Starting program: /btrfs/johnc/tmp/kill_gdb 
[Thread debugging using libthread_db enabled]
Cannot find new threads: generic error
(gdb)

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[Bug threads/9635] Cannot find new threads: generic error

[john.carter at tait dot co.nz]

http://sourceware.org/bugzilla/show_bug.cgi?id=9635

John Carter <john.carter at tait dot co.nz> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |john.carter at tait dot
                   |                            |co.nz
            Version|6.8                         |7.2
           Severity|enhancement                 |normal

--- Comment #3 from John Carter <john.carter at tait dot co.nz> 2011-05-27 05:34:33 UTC ---
If file being debugged uses libpthread AND has an external symbol "stack_used"
gdb dies before the debugged program enters "main" with the message...
[Thread debugging using libthread_db enabled]
Cannot find new threads: generic error

In the attached file, for example you change all occurrences of "stack_used" by
"tack_used" and recompile and run gdb executes normally.

If you leave it as "stack_used", gdb dies with an entirely mystifying error
message!

Thanks.

Environment

uname -a
Linux parore 2.6.35-28-generic-pae #50-Ubuntu SMP Fri Mar 18 20:43:15 UTC 2011
i686 GNU/Linux
/usr/bin/gcc --version
gcc (Ubuntu/Linaro 4.4.4-14ubuntu5) 4.4.5

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[Bug threads/9635] Cannot find new threads: generic error

[pedro at codesourcery dot com]

http://sourceware.org/bugzilla/show_bug.cgi?id=9635

Pedro Alves <pedro at codesourcery dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         AssignedTo|unassigned at sourceware    |pedro at codesourcery dot
                   |dot org                     |com

--- Comment #4 from Pedro Alves <pedro at codesourcery dot com> 2011-05-27 10:46:01 UTC ---
Created attachment 5757
  --> http://sourceware.org/bugzilla/attachment.cgi?id=5757
fix

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[Bug threads/9635] Cannot find new threads: generic error

[pedro at codesourcery dot com]

http://sourceware.org/bugzilla/show_bug.cgi?id=9635

--- Comment #5 from Pedro Alves <pedro at codesourcery dot com> 2011-05-27 10:49:48 UTC ---
Thanks for the testcase.  It makes the problem dead obvious --- GDB is looking
up symbols in the globally, instead of on the object thread_db requests.

I've attached a proposed fix.  My thread_db always passes in a basenamed
obj=libpthread.so.0.  Not sure that'll always be the case.  Anyone know
otherwise?

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[Bug threads/9635] Cannot find new threads: generic error

[gbenson at redhat dot com]

http://sourceware.org/bugzilla/show_bug.cgi?id=9635

Gary Benson <gbenson at redhat dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |gbenson at redhat dot com

--- Comment #6 from Gary Benson <gbenson at redhat dot com> 2011-05-27 11:03:46 UTC ---
Not sure how relevant this is, but there is a function libpthread_name_p
defined in solib.c.

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[Bug threads/9635] Cannot find new threads: generic error

[pedro at codesourcery dot com]

http://sourceware.org/bugzilla/show_bug.cgi?id=9635

--- Comment #7 from Pedro Alves <pedro at codesourcery dot com> 2011-05-27 11:08:00 UTC ---
Yeah, didn't look useful.

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[Bug threads/9635] Cannot find new threads: generic error

[gbenson at redhat dot com]

http://sourceware.org/bugzilla/show_bug.cgi?id=9635

--- Comment #8 from Gary Benson <gbenson at redhat dot com> 2011-05-27 12:30:06 UTC ---
Fair enough :)

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[Bug threads/9635] Cannot find new threads: generic error

[pedro at codesourcery dot com]

http://sourceware.org/bugzilla/show_bug.cgi?id=9635

--- Comment #9 from Pedro Alves <pedro at codesourcery dot com> 2011-06-01 15:48:33 UTC ---
The patch breaks thread debugging of threaded static programs.  E.g., the
gdb.threads/staticthreads test:

Breakpoint 3, ps_pglobal_lookup (ph=0xf248f8, obj=0x7ffff5b84541
"libpthread.so.0", name=0x7ffff5b84665 "nptl_version", sym_addr=0x7fffffffd5c8)
    at ../../src/gdb/proc-service.c:207
207       ALL_OBJFILES (objfile)

There's no libpthread.so loaded by this program, so all symbol lookups
thread_db tries fail...

Any ideas?

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[Bug threads/9635] Cannot find new threads: generic error

[pedro at codesourcery dot com]

http://sourceware.org/bugzilla/show_bug.cgi?id=9635

--- Comment #10 from Pedro Alves <pedro at codesourcery dot com> 2011-06-01 15:53:25 UTC ---
Is there any reason glibc couldn't move the symbols it wants to check against
to the private namespace (nptl_version ==> __nptl_version, etc.)?

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[Bug threads/9635] Cannot find new threads: generic error

[pedro at codesourcery dot com]

http://sourceware.org/bugzilla/show_bug.cgi?id=9635

Pedro Alves <pedro at codesourcery dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         AssignedTo|pedro at codesourcery dot   |unassigned at sourceware
                   |com                         |dot org

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[Bug threads/9635] Cannot find new threads: generic error

[pedro at codesourcery dot com]

http://sourceware.org/bugzilla/show_bug.cgi?id=9635

Pedro Alves <pedro at codesourcery dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|ASSIGNED                    |NEW
                 CC|                            |pedro at codesourcery dot
                   |                            |com

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[Bug threads/9635] Cannot find new threads: generic error

[palves at redhat dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=9635

Pedro Alves <palves at redhat dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         Depends on|                            |17629

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[Bug threads/9635] Cannot find new threads: generic error

[palves at redhat dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=9635

--- Comment #11 from Pedro Alves <palves at redhat dot com> ---
Filed glibc bug: https://sourceware.org/bugzilla/show_bug.cgi?id=17629

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[Bug threads/9635] Cannot find new threads: generic error

[cgrayce at gmail dot com]

------- Additional Comments From cgrayce at gmail dot com  2010-06-04 09:21 -------
(In reply to comment #0)

Identical problem, with plain C code that also uses no threads, but does use
dynamic libraries:

% gdb xques
GNU gdb (GDB) 7.1-ubuntu
Copyright (C) 2010 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.  Type "show copying"
and "show warranty" for details.
This GDB was configured as "i486-linux-gnu".
For bug reporting instructions, please see:
<http://www.gnu.org/software/gdb/bugs/>...
Reading symbols from /home/cgrayce/bin/xques...done.
(gdb) run -i 31d_uconvert.xml example-xhtml
Starting program: /home/cgrayce/bin/xques -i 31d_uconvert.xml example-xhtml
[Thread debugging using libthread_db enabled]
Cannot find new threads: generic error

ldd `which xques`
	linux-gate.so.1 =>  (0x00ce2000)
	libxml2.so.2 => /usr/lib/libxml2.so.2 (0x00164000)
	libz.so.1 => /lib/libz.so.1 (0x0035a000)
	libm.so.6 => /lib/tls/i686/cmov/libm.so.6 (0x00642000)
	libc.so.6 => /lib/tls/i686/cmov/libc.so.6 (0x0036f000)
	libdl.so.2 => /lib/tls/i686/cmov/libdl.so.2 (0x00ef2000)
	/lib/ld-linux.so.2 (0x0091c000)

uname -a
Linux spock 2.6.32-22-generic #35-Ubuntu SMP Tue Jun 1 14:17:36 UTC 2010 i686
GNU/Linux


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