[GitHub] [nuttx] zyfeier commented on pull request #8175: sched/semaphore: increase sem count when holder task exit

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zyfeier commented on PR #8175:
URL: https://github.com/apache/nuttx/pull/8175#issuecomment-1396333791

   > @zyfeier
   > 
   > > Increase the sem count when the holder task exit, to avoid lock failure 
at next time.
   > 
   > Could you explain the lock failure more concretely? Is it possible to 
detect the failure with ostest?
   
   Here is the test case for this issue, need enable 
CONFIG_PRIORITY_INHERITANCE and CONFIG_SMP.
   This case will finally stop at` nxmutex_lock(&group->tg_joinlock)`,  and we 
can see no one is holding
   this lock, but the semcount value is 0.
   
   ```
   static pthread_t g_bench_threads;
   int priority = 98;
   
   static void bench_spawn_helper(void *args)
   {
     UNUSED(args);
     pthread_exit(NULL);
   }
   
   static void thread_test(void)
   {
     struct sched_param param;
     pthread_attr_t attr;
     int policy;
   
     pthread_attr_init(&attr);
     pthread_getschedparam(0, &policy, &param);
     param.sched_priority = priority;
     pthread_attr_setschedparam(&attr, &param);
   
     pthread_create(&g_bench_threads, &attr,
                   (pthread_startroutine_t)bench_spawn_helper, NULL);
     printf("Pthread Create Success!\n");
     pthread_attr_destroy(&attr);
   }
   
   int main(int argc, FAR char *argv[])
   {
     int i = 0;
     for (;;)
       {
         thread_test();
         pthread_cancel(g_bench_threads);
         printf("No.%d -> Test Success!\n", i);
         i++;
       }
   
     return 0;
   }
   ```


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