On 03/15/2018 12:07 PM, Pintu Kumar wrote:
> On Thu, Mar 15, 2018 at 3:29 PM, Philippe Gerum <r...@xenomai.org> wrote:
>> On 03/15/2018 10:51 AM, Pintu Kumar wrote:
>>> On Thu, Mar 15, 2018 at 2:08 PM, Philippe Gerum <r...@xenomai.org> wrote:
>>>> On 03/15/2018 09:24 AM, Pintu Kumar wrote:
>>>>> Hi All,
>>>>>
>>>>> I am trying to test rt_cond_bind() and rt_task_unblock() API with a
>>>>> simple thread program using the Xenomai native skin, and with xenomai
>>>>> 3.0.6.
>>>>>
>>>>> But, during call to rt_task_unblock(&task1) from the main function, I
>>>>> get the segmentation fault.
>>>>>
>>>>
>>>> Use gdb to get more information about the crash.
>>>>
>>>
>>> Here is the gdb output:
>>>
>>> Thread 1 "cond_bin_test" received signal SIGSEGV, Segmentation fault.
>>> cobalt_monitor_exit (mon=0x3c) at internal.c:232
>>> warning: Source file is more recent than executable.
>>> 232 state = get_monitor_state(mon);
>>> (gdb) backtrace
>>> #0 cobalt_monitor_exit (mon=0x3c) at internal.c:232
>>> #1 0x0000ffffb7f80058 in monitor_exit (sobj=<optimized out>) at
>>> syncobj.c:72
>>> #2 syncobj_unlock (sobj=<optimized out>, syns=0xfffffffff960) at
>>> syncobj.c:279
>>> #3 0x0000ffffb7f81be8 in threadobj_unblock
>>> (thobj=thobj@entry=0xffffb739df88)
>>> at threadobj.c:1570
>>> #4 0x0000ffffb7fa13b0 in rt_task_unblock (task=<optimized out>) at
>>> task.c:1353
>>> #5 0x00000000004011d8 in main (argc=1, argv=0x413710) at cond_bin_test:92
>>> (gdb)
>>>
>>> Its crashing inside, rt_task_unblock().
>>>
>>> I also get these back trace on console:
>>>
>>> Kernel backtrace :
>>>
>>> root@:~/mine/xenomai-3/testsuite/cond# [ 7923.372700]
>>> cond_bind_test[26257]: unhandled level 2 translation fault (11) at
>>> 0x00000040, esr 0x92000006
>>>
>>> [ 7923.381677] mm_pgd = ffff800031fde000, hw_pgd = ffff800031fdc000
>>>
>>> [ 7923.387684] [00000040] *pgd=00000000340fe003,
>>> *pud=00000000316b4003, *pmd=0000000000000000
>>>
>>> [ 7923.395962]
>>> ....
>>>
>>> It looks like there is some clean up problem that needs to be handled.
>>>
>>>
>>> I could not find any sample reference about how to use rt_cond_bind()
>>> along with rt_task_unblock().
>>> If you can share a sample logic, it would be great.
>>>
>>>
>>>>> # ./cond_bin_test
>>>>> PINTU: Inside bind_test task....
>>>>> PINTU: Before rt_task_unblock
>>>>> Segmentation fault (core dumped)
>>>>>
>>>>> This is the code snippet for the program:
>>>>>
>>>>> void bind_test(...)
>>>>> {
>>>>> ....
>>>>> err = rt_cond_bind(&cond, "COND1", TM_INFINITE);
>>>>> if (err == -EINTR)
>>>>> printf("error....");
>>>>> }
>>>>>
>>>>> int main(...)
>>>>> {
>>>>> ....
>>>>> rt_task_create(&bind_test, .....);
>>>>> rt_task_start(&bind_test, .......);
>>>>>
>>>>> err = rt_task_unblock(&bind_test);
>>>>>
>>>>> rt_task_delete(&bind_test);
>>>>>
>>>>>
>>>>> return 0;
>>>>> }
>>>>>
>>>>> What is wrong with the above sample ?
>>>>> I suppose this code was working on Xenomai 2.6.x
>>>>>
>>>>> If there is any thing missing please let me know.
>>>>
>>>> Your full test code. Task descriptor definition and flags are missing.
>>>>
>>>
>>> Makefile is like this:
>>>
>>> target = cond_bind_test
>>> skin = alchemy
>>> CC := $(shell $(INSTALL_PATH)/xeno-config --cc)
>>> CFLAGS := $(shell $(INSTALL_PATH)/xeno-config --skin=$(skin) --cflags)
>>> LDFLAGS := $(shell $(INSTALL_PATH)/xeno-config --skin=$(skin) --ldflags)
>>> $(target): cond_bind_test
>>> $(CC) -o $@ $< $(CFLAGS) $(LDFLAGS)
>>>
>>> ------------
>>> The majority of sample program as a given above. I just removed some
>>> error condition checks and declarations.
>>> Task details are as follows:
>>>
>>> err = rt_task_create(&task1, NULL, 0, 99, T_JOINABLE);
>>> err = rt_task_start(&task1, &bind_test, NULL);
>>> err = rt_task_unblock(&bind_test);
>>>
>>> Apart from these there is nothing more...
>>>
>>> If you need more information please let me know.
>>>
>>
>> __Full test code__, no ellipsis, verbatim, please. Or a self-contained
>> test case reproducing the issue if you can't easily extract the faulting
>> code from the original app. Where you define the task descriptor, and
>> the exact sequence of your code could be involved in the issue.
>>
>>> I think we can easily reproduce it on Xenomai 3.0.6 if we just call
>>> these functions.
>>
>> Did you try running testsuite/alchemy/*? task-9 is testing
>> rt_task_unblock().
>>
>
> Yes, this work because here we are not using rt_cond_bind.
> The issue is when we combine: rt_cond_bind, with rt_task_unblock
> What we are trying to do here is:
> In the RT task, we are calling rt_cond_bind, so the task will block
> for the condition, and wait for the err == -EINTR
> Then, in the main function we are calling : rt_task_block.
> Thus rt_task_unblock should unblock the task from rt_cond_bind and set
> the err as -EINTR.
>
> But instead of this, rt_task_unblock is crashing.
> And the error reason is: error: Resource temporarily unavailable
>
> One observation:
> If I use rt_task_sleep(ONE_SECOND) just before rt_cond_bind in task
> function, then the test is working fine.
> So, I assume, we need to wait for some time before calling
> rt_cond_bind, for the resource to be created.
> Please correct me if I am wrong.
>
Sprinkling the code with "magical" delays is a documented way of
papering over bugs which will most certainly bite at some point later
on, so I would clearly not do that, and go to the bottom of the issue
instead.
Since you still did not provide me with any self-contained code
demonstrating the bug, in order to help me in checking the Xenomai code
for any issue, I guess there is no urgency on getting this problem
solved on your end. I'm queuing this report to my todo list. I may get
back to you when I have some cycles left for digging this deeper.
Thanks,
--
Philippe.
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