[Xenomai] Problem with rt_cond_wait and rt_cond_signal combination

[Pintu Kumar]

Hi,

We are facing one issue on Xenomai-3 on x86_64 system.
Kernel: 4.9.51
ipipe version: 4
# /usr/xenomai/sbin/version
Xenomai/cobalt v3.0.6 -- #5956064 (2018-03-20 12:13:33 +0100)

Its a very simple API level test.
We create a condition variable and wait for the condition inside a task.
Then, we immediately signal the condition from the main thread, and simply
wait for the test to finish.

But we observed that condition task is never getting released, and the
program hangs.

This is the output:
--------------------------
# ./condsignal
cond_task --> started
main --> cond signal success: 0
Waiting for task to finish....
^C


This is the code snippet that was used.
-----------------------------------------------------
# cat condsignal.c

/*
 * 1. Create an condition variable and wait inside a task.
 * 2. Delete the condition variable from main task.
 * 3. Observe that the condition wait is released and task ends normally.
 * 4. Finally main task should exit normally.
 *
 * */
#include <stdio.h>
#include <stdlib.h>
#include <sys/mman.h>
#include <alchemy/task.h>
#include <alchemy/mutex.h>
#include <alchemy/cond.h>
#include <alchemy/task.h>

static RT_COND cond;
static RT_MUTEX mutex;

static void cond_task(void *cookie)
{
        int err;

        printf("%s --> started \n", __func__);
        rt_mutex_acquire(&mutex, TM_INFINITE);
        err = rt_cond_wait(&cond, &mutex, TM_INFINITE);
        rt_mutex_release(&mutex);
        if (err) {
                printf("rt_cond_wait failed, err = %d", err);
                return;
        }
        printf("%s --> cond wait done\n", __func__);
}

int main(int argc, char **argv)
{
        int err;
        RT_TASK task1;

        mlockall(MCL_CURRENT | MCL_FUTURE);

        err = rt_mutex_create(&mutex, NULL);
        err = rt_cond_create(&cond, "cond_test");
        err = rt_task_create(&task1, NULL, 0, 99, T_JOINABLE);
        err = rt_task_start(&task1, &cond_task, NULL);
        rt_mutex_acquire(&mutex, TM_INFINITE);
        err = rt_cond_signal(&cond);
        rt_mutex_release(&mutex);
        if (err) {
                printf("Error: rt_cond_signal failed, err = %d", err);
                exit(-1);
        }
        printf("%s --> cond signal success: %d\n", __func__, err);
        printf("Waiting for task to finish....\n");
        rt_task_join(&task1);

        return 0;
}
-----------------------------------------------------

Is there any fix available in Xenomai-3 for this?
Please let me know if there is something wrong here.


Thanks,
Pintu

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