[Bug threads/10757] New: GDB does not attach all threads of a multithreaded process => inferior gets SIGTRAP

["ppluzhnikov at google dot com" <sourceware-bugzilla at sourceware dot org>]

Possibly related to PR8963.

This was originally reported with gdbserver across a relatively high-latency
connection: attach remote process, set breakpoints, continue:

  Program terminated with signal SIGTRAP, Trace/breakpoint trap.
  The program no longer exists.

Reproduces with attached test case on Fedora 11 with both
  GNU gdb (GDB) Fedora (6.8.50.20090302-38.fc11)
  GNU gdb (GDB) 7.0.50.20091011-cvs

$ ulimit -s 32
$ ./a.out 20 &
[2] 16717

$ ~/gdb-cvs/build/gdb/gdb --pid $(pgrep a.out)
GNU gdb (GDB) 7.0.50.20091011-cvs
...
This GDB was configured as "i686-pc-linux-gnu".
For bug reporting instructions, please see:
<http://www.gnu.org/software/gdb/bugs/>.
Attaching to process 16717
Reading symbols from /home/paul/tmp/a.out...done.
Reading symbols from /lib/libpthread.so.0...Reading symbols from
/usr/lib/debug/lib/libpthread-2.10.1.so.debug...done.
[Thread debugging using libthread_db enabled]
[New Thread 0xb7f3eb70 (LWP 5139)]
(no debugging symbols found)...done.
Loaded symbols for /lib/libpthread.so.0
Reading symbols from /lib/libc.so.6...Reading symbols from
/usr/lib/debug/lib/libc-2.10.1.so.debug...done.
(no debugging symbols found)...done.
Loaded symbols for /lib/libc.so.6
Reading symbols from /lib/ld-linux.so.2...Reading symbols from
/usr/lib/debug/lib/ld-2.10.1.so.debug...done.
(no debugging symbols found)...done.
Loaded symbols for /lib/ld-linux.so.2
0x001ef424 in __kernel_vsyscall ()
(gdb) b foo
Breakpoint 1 at 0x80485c7: file manythreads2.c, line 10.
(gdb) commands 1
>c
>end
(gdb) c
[Thread 0xb7f3eb70 (LWP 5139) exited]

Program terminated with signal SIGTRAP, Trace/breakpoint trap.
The program no longer exists.
(gdb) quit
[2]+  Trace/breakpoint trap   (core dumped) ./a.out 20


It appears that to trigger the bug, I need a program which rapidly creates
threads while gdb/gdbserver is attaching.

The same program works fine when started from within GDB. Race in attach?

-- 
           Summary: GDB does not attach all threads of a multithreaded
                    process => inferior gets SIGTRAP
           Product: gdb
           Version: unknown
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: threads
        AssignedTo: unassigned at sourceware dot org
        ReportedBy: ppluzhnikov at google dot com
                CC: gdb-prs at sourceware dot org
 GCC build triplet: i686-pc-linux-gnu
  GCC host triplet: i686-pc-linux-gnu
GCC target triplet: i686-pc-linux-gnu


http://sourceware.org/bugzilla/show_bug.cgi?id=10757

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