ostest/cancel.c: fix busyloop after improving ostest priority

Because the priority of ostest was increased, the priority of the main thread also increased. Newly created threads still used the default priority, causing the parent thread to prematurely cancel the child thread. This resulted in the child thread not being properly garbage collected, leading to a system busy loop.

Signed-off-by: yangao1 <yangao1@xiaomi.com>

Author: yangao1

testing/ostest/cancel.c

@@ -287,8 +287,8 @@ static FAR void *asynch_waiter(FAR void *parameter)
        ASSERT(false);
     }
 
-  /* Then wait a bit.  We should be canceled aynchronously while waiting, but
-   * the cancellation should pend because we are non-cancellable.
+  /* Then wait a bit.  We should be canceled asynchronously while waiting,
+   * but the cancellation should pend because we are non-cancelable.
    */
 
   usleep(250 * 1000);
@@ -321,6 +321,7 @@ static FAR void *asynch_waiter(FAR void *parameter)
 static void start_thread(FAR void *(*entry)(FAR void *), pthread_t *waiter,
                         int cancelable)
 {
+  struct sched_param param;
   pthread_attr_t attr;
   int status;
 
@@ -356,6 +357,18 @@ static void start_thread(FAR void *(*entry)(FAR void *), pthread_t *waiter,
       ASSERT(false);
     }
 
+  param.sched_priority = PRIORITY;
+  printf("start_thread: Parent thread priority=%d\n",
+          param.sched_priority);
+
+  status = pthread_attr_setschedparam(&attr, &param);
+  if (status != 0)
+    {
+      printf("start_thread: ERROR pthread_attr_setschedparam failed,"
+             "status=%d\n", status);
+      ASSERT(false);
+    }
+
   status = pthread_attr_setstacksize(&attr, STACKSIZE);
   if (status != 0)
     {