Re: [Xenomai] segfault using rt_printf service

["Alessio Margan]

On 09/14/2012 05:11 PM, Gilles Chanteperdrix wrote:
> On 09/14/2012 04:33 PM, Alessio Margan @ IIT wrote:
>> Hi all,
>>
>> I'm switching from xenomai 2.5.6 to 2.6.1 using
>> adeos-ipipe-2.6.38.8-x86-2.11-01.patch
>> In this test I have 2 threads :
>> - rx_udp receive udp packets from dsp boards at 1kHz
>> - boards_test send udp packets at 1kHz
>>
>> I got segfault in printer_loop thread, the point is that if I change env
>> var RT_PRINT_PERIOD to about 10 or 1000 (default is 100 ms) I do not
>> have segfault.
>>
>> Any suggestion ?
>>
>> Program received signal SIGSEGV, Segmentation fault.
>> [Switching to Thread 0xb7d1ab70 (LWP 5998)]
>> 0xb7d7cb0c in fwrite () from /lib/i686/cmov/libc.so.6
>> (gdb) bt
>> #0  0xb7d7cb0c in fwrite () from /lib/i686/cmov/libc.so.6
>> #1  0xb7fccbf9 in print_buffers () from /usr/xenomai/lib/libxenomai.so.0
>> #2  0xb7fcd867 in printer_loop () from /usr/xenomai/lib/libxenomai.so.0
>> #3  0xb7fb5955 in start_thread () from /lib/i686/cmov/libpthread.so.0
>> #4  0xb7dec5ee in clone () from /lib/i686/cmov/libc.so.6
> Since you seem to be able to catch the error with gdb, maybe try and
> understand the reason for the segfault? The first, quick check, is to
> type "info register", type cat /proc/pid/maps in another terminal, and
> check that the stack pointer is in a valid mapping, to check if we do
> not have a stack overflow.
>
> If you fail to find the error, please try and reduce the test program to
> a simple test case, as simple as needed for the bug to happen and post
> it on this mailing list, this would allow us to reproduce the issue.
>

Thanks ...

try to learn how to read debug info ...
here is what I got

Program received signal SIGSEGV, Segmentation fault.
[Switching to Thread 0xb7d1ab70 (LWP 1789)]
0xb7d7cb0c in fwrite () from /lib/i686/cmov/libc.so.6
(gdb) info register
eax            0xc9cfa3b    211614267
ecx            0xe634c0    15086784
edx            0x19db    6619
ebx            0xb7e62ff4    -1209651212
esp            0xb7d1a23c    0xb7d1a23c
ebp            0xb7d1a258    0xb7d1a258
esi            0xe634c0    15086784
edi            0xe    14
eip            0xb7d7cb0c    0xb7d7cb0c <fwrite+44>
eflags         0x210202    [ IF RF ID ]
cs             0x73    115
ss             0x7b    123
ds             0x7b    123
es             0x7b    123
fs             0x0    0
gs             0x33    51
(gdb) info threads
   4 Thread 0xb7d0db70 (LWP 1791)  0xb7fe2424 in __kernel_vsyscall ()
   3 Thread 0xb7d12b70 (LWP 1790)  0xb7fe2424 in __kernel_vsyscall ()
* 2 Thread 0xb7d1ab70 (LWP 1789)  0xb7d7cb0c in fwrite () from 
/lib/i686/cmov/libc.so.6
   1 Thread 0xb7d1e6e0 (LWP 1786)  0xb7fe2424 in __kernel_vsyscall ()
(gdb)



embedded@ccub-deb:~$ cat /proc/1789/maps
08048000-0808e000 r-xp 00000000 00:10 10629494   
/home/embedded/robolli_nfs/v2.0/examples/test_main
0808e000-08090000 rw-p 00045000 00:10 10629494   
/home/embedded/robolli_nfs/v2.0/examples/test_main
08090000-0c9ef000 rw-p 00000000 00:00 0          [heap]
b6f4d000-b7d09000 rw-p 00000000 00:00 0
b7d09000-b7d0a000 ---p 00000000 00:00 0
b7d0a000-b7d0e000 rw-p 00000000 00:00 0
b7d0e000-b7d0f000 ---p 00000000 00:00 0
b7d0f000-b7d13000 rw-p 00000000 00:00 0
b7d13000-b7d14000 ---p 00000000 00:00 0
b7d14000-b7d1b000 rw-p 00000000 00:00 0
b7d1b000-b7d1e000 rw-s f800d000 00:05 88         /dev/rtheap
b7d1e000-b7d20000 rw-p 00000000 00:00 0
b7d20000-b7e60000 r-xp 00000000 08:01 114961     
/lib/i686/cmov/libc-2.11.3.so
b7e60000-b7e61000 ---p 00140000 08:01 114961     
/lib/i686/cmov/libc-2.11.3.so
b7e61000-b7e63000 r--p 00140000 08:01 114961     
/lib/i686/cmov/libc-2.11.3.so
b7e63000-b7e64000 rw-p 00142000 08:01 114961     
/lib/i686/cmov/libc-2.11.3.so
b7e64000-b7e67000 rw-p 00000000 00:00 0
b7e67000-b7e84000 r-xp 00000000 08:01 89965      /lib/libgcc_s.so.1
b7e84000-b7e85000 rw-p 0001c000 08:01 89965      /lib/libgcc_s.so.1
b7e85000-b7ea9000 r-xp 00000000 08:01 114943     
/lib/i686/cmov/libm-2.11.3.so
b7ea9000-b7eaa000 r--p 00023000 08:01 114943     
/lib/i686/cmov/libm-2.11.3.so
b7eaa000-b7eab000 rw-p 00024000 08:01 114943     
/lib/i686/cmov/libm-2.11.3.so
b7eab000-b7eac000 rw-p 00000000 00:00 0
b7eac000-b7f95000 r-xp 00000000 08:01 82575      
/usr/lib/libstdc++.so.6.0.13
b7f95000-b7f99000 r--p 000e9000 08:01 82575      
/usr/lib/libstdc++.so.6.0.13
b7f99000-b7f9a000 rw-p 000ed000 08:01 82575      
/usr/lib/libstdc++.so.6.0.13
b7f9a000-b7fa1000 rw-p 00000000 00:00 0
b7fa1000-b7fa3000 r-xp 00000000 08:01 114942     
/lib/i686/cmov/libdl-2.11.3.so
b7fa3000-b7fa4000 r--p 00001000 08:01 114942     
/lib/i686/cmov/libdl-2.11.3.so
b7fa4000-b7fa5000 rw-p 00002000 08:01 114942     
/lib/i686/cmov/libdl-2.11.3.so
b7fa5000-b7fa6000 r-xp 00000000 08:01 149583     
/usr/xenomai/lib/librtdm.so.1.0.0
b7fa6000-b7fa7000 rw-p 00000000 08:01 149583     
/usr/xenomai/lib/librtdm.so.1.0.0
b7fa7000-b7fae000 r-xp 00000000 08:01 114960     
/lib/i686/cmov/librt-2.11.3.so
b7fae000-b7faf000 r--p 00006000 08:01 114960     
/lib/i686/cmov/librt-2.11.3.so
b7faf000-b7fb0000 rw-p 00007000 08:01 114960     
/lib/i686/cmov/librt-2.11.3.so
b7fb0000-b7fc5000 r-xp 00000000 08:01 114951     
/lib/i686/cmov/libpthread-2.11.3.so
b7fc5000-b7fc6000 r--p 00014000 08:01 114951     
/lib/i686/cmov/libpthread-2.11.3.so
b7fc6000-b7fc7000 rw-p 00015000 08:01 114951     
/lib/i686/cmov/libpthread-2.11.3.so
b7fc7000-b7fca000 rw-p 00000000 00:00 0
b7fca000-b7fcf000 r-xp 00000000 08:01 149564     
/usr/xenomai/lib/libxenomai.so.0.0.0
b7fcf000-b7fd0000 rw-p 00005000 08:01 149564     
/usr/xenomai/lib/libxenomai.so.0.0.0
b7fd0000-b7fda000 r-xp 00000000 08:01 149576     
/usr/xenomai/lib/libpthread_rt.so.1.0.0
b7fda000-b7fdb000 rw-p 00009000 08:01 149576     
/usr/xenomai/lib/libpthread_rt.so.1.0.0
b7fdb000-b7fdc000 rw-p 00000000 00:00 0
b7fdc000-b7fdf000 rw-s f8885000 00:05 88         /dev/rtheap
b7fdf000-b7fe0000 r-xs f8012000 00:05 88         /dev/rtheap
b7fe0000-b7fe2000 rw-p 00000000 00:00 0
b7fe2000-b7fe3000 r-xp 00000000 00:00 0          [vdso]
b7fe3000-b7ffe000 r-xp 00000000 08:01 89948      /lib/ld-2.11.3.so
b7ffe000-b7fff000 r--p 0001b000 08:01 89948      /lib/ld-2.11.3.so
b7fff000-b8000000 rw-p 0001c000 08:01 89948      /lib/ld-2.11.3.so
bffdf000-c0000000 rw-p 00000000 00:00 0          [stack]

TIA

Alessio

-- 

ISTITUTO ITALIANO
DI TECNOLOGIA

Alessio Margan
/Senior Technician/
/Advanced Robotics/

Via Morego, 30 16163 Genova 
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