threads/2371: gdbserver can't step in thread

[loic.gautheur@wanadoo.fr]

>Number:         2371
>Category:       threads
>Synopsis:       gdbserver can't step in thread
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    unassigned
>State:          open
>Class:          support
>Submitter-Id:   net
>Arrival-Date:   Thu Nov 29 10:18:01 UTC 2007
>Closed-Date:
>Last-Modified:
>Originator:     loic.gautheur@wanadoo.fr
>Release:        GDB 5.3
>Organization:
>Environment:
GDB 5.3 and GDBSERVER 5.3 under debian woody
>Description:
Hi,
I have a problem using gdbserver 5.3 for debuging multi-threaded
applications. If I use gdb 5.3 to debug the application everything works.
my problem is when I put a breakpoint in a thread and the thread encounter the breakpoint the application stops, then i try to STEP to the next line and then if I use gdb the application run ,execute other threads and stop on the next line (normal behaviour )
but when using gdbserver the application receive a SIGTRAP and stop.
PS: Attached you can find the traces I've got first using GDB and after using GDBSERVER

Loic Gautheur
>How-To-Repeat:
use the print-threads.c program in the testsuite of gdb set slow to 1
then put a breakpoint at line 43
run the application
when you encounter the breakpoint clear it and then
use the STEP command.
>Fix:

>Release-Note:
>Audit-Trail:
>Unformatted:
----gnatsweb-attachment----
Content-Type: text/plain; name="bug_gdbserver"
Content-Disposition: inline; filename="bug_gdbserver"

 
/********************* normal behaviour using GDB **********************/
(gdb) br print-threads.c:43
Breakpoint 2 at 0x8048667: file print-threads.c, line 43.
(gdb) r
Starting program: /i500/test/a.out
[New Thread 1024 (LWP 210)]
[New Thread 2049 (LWP 211)]
[New Thread 1026 (LWP 212)]
Print 1, thread 0
[New Thread 2051 (LWP 213)]
Print 1, thread 1
[Switching to Thread 1026 (LWP 212)]

Breakpoint 2, thread_function (arg=0xbffffcdc) at print-threads.c:43
43          if (slow)
(gdb) clear print-threads.c:43
Deleted breakpoint 2
(gdb) s
Print 2, thread 1
Print 3, thread 1
45              printf ("Print 2, thread %d\n", my_number);
(gdb) s
Print 4, thread 1
Print 5, thread 1
Bye from 1
Print 2, thread 0
[New Thread 3076 (LWP 214)]
Print 1, thread 2
Print 2, thread 2
46              sleep (1);
(gdb) s
Print 3, thread 2
Print 4, thread 2
Print 5, thread 2
Bye from 2
[New Thread 4101 (LWP 215)]
Print 1, thread 3
Print 2, thread 3
47              printf ("Print 3, thread %d\n", my_number);
(gdb) c
Continuing.
Print 3, thread 3
Print 3, thread 0
[New Thread 5126 (LWP 216)]
Print 4, thread 3
Print 4, thread 0
Print 1, thread 4
Print 5, thread 0
Print 2, thread 4
Print 5, thread 3
Bye from 0
Bye from 3
Print 3, thread 4
Print 4, thread 4
Print 5, thread 4
Bye from 4
Done

Program exited normally.
/********************* end of normal behaviour with GDB *******************/

/********************* PROBLEM using GDBSERVER **************************/
(gdb) target remote localhost:2345
Remote debugging using localhost:2345
0x400012d0 in ?? ()
(gdb) c
Continuing.
[New Thread 1024]
[New Thread 1026]
[Switching to Thread 1026]

Breakpoint 1, thread_function (arg=0xbffffcec) at print-threads.c:43
43          if (slow)
(gdb) clear print-threads:43
No source file named print-threads.
(gdb) clear print-threads.c:43
Deleted breakpoint 1
(gdb) s

Program received signal SIGTRAP, Trace/breakpoint trap.
[Switching to Thread 1024]
0x4005187f in sigsuspend () from /lib/libc.so.6
(gdb) s
Single stepping until exit from function sigsuspend,
which has no line number information.
0x4001c879 in __pthread_wait_for_restart_signal () from /lib/libpthread.so.0
(gdb) c
Continuing.

Program exited normally.
/********************* END of PROBLEM GDBSERVER **************************/