core: change real-time task creation to new transitioning method

The old clone based hack will be removed soon.

1 files changed, 18 insertions, 66 deletions

diff --git a/src/litmus.c b/src/litmus.c
index 89d0f86..426e9e2 100644
--- a/src/litmus.c
+++ b/src/litmus.c
@@ -49,44 +49,6 @@ type name(type1 arg1,type2 arg2, type3 arg3, type4 arg4)	      	\
         return syscall(__NR_##name, arg1, arg2, arg3, arg4);    \
 }
 
-
-/* clear the TID in the child */
-#define CLONE_CHILD_CLEARTID    0x00200000      
-/* set the TID in the child */
-#define CLONE_CHILD_SETTID      0x01000000
-/* don't let the child run before we have completed setup */
-#define CLONE_STOPPED           0x02000000      
-/* litmus clone flag */
-#define CLONE_REALTIME          0x10000000
-
-/* CLONE_REALTIME is necessary because CLONE_STOPPED will put a SIGSTOP in 
- * the pending signal queue. Thus the first thing a newly created task will
- * do after it is released is to stop, which is not what we want
- * 
- * CLONE_REALTIME just sets the status to TASK_STOPPED without queueing a 
- * signal.
- */
-
-
-/* this is essentially a fork with CLONE_STOPPED */
-/* #define CLONE_LITMUS  CLONE_STOPPED | CLONE_CHILD_CLEARTID | CLONE_CHILD_SETTID */
-#define CLONE_LITMUS CLONE_REALTIME | CLONE_CHILD_CLEARTID | CLONE_CHILD_SETTID
-
-/* we need to override libc because it wants to be clever 
- * and rejects our call without presenting it even to the kernel
- */
-#define __NR_raw_clone          120
-
-
-_syscall2(int, raw_clone, unsigned long, flags, unsigned long, child_stack)
-
-int fork_rt(void) 
-{
-        int rt_task = raw_clone(CLONE_LITMUS, 0);
-        return rt_task;
-}
-
-
 const char* get_scheduler_name(spolicy scheduler) 
 {
         const char* name;
@@ -123,46 +85,36 @@ const char* get_scheduler_name(spolicy scheduler)
         return name;
 }
 
+static void tperrorx(char* msg) 
+{
+        fprintf(stderr, 
+                "Task %d: %s: %m",
+                getpid(), msg);
+        exit(-1);
+}
 
 /* common launch routine */
 int __launch_rt_task(rt_fn_t rt_prog, void *rt_arg, rt_setup_fn_t setup, 
                      void* setup_arg) 
 {
         int ret;
-        int rt_task = fork_rt();
-
-        if (rt_task < 0) 
-                return rt_task;
+        int rt_task = fork();
 
-        if (rt_task > 0) {
-                /* we are the controller task */                        
-                ret = setup(rt_task, setup_arg);
-                if (ret < 0) {
-                        /* we have a problem: we created the task but
-                         * for some stupid reason we cannot set the real-time
-                         * parameters. We must clean up the stopped task.
-                         */
-                        kill(rt_task, SIGKILL);
-                        /* syscall will have set errno, we don't have to do
-                         * anything
-                         */
-                        return -1;
-                }
-                ret = prepare_rt_task(rt_task);
-                if (ret < 0) {
-                        /* same problem as above*/
-                        kill(rt_task, SIGKILL);
-                        rt_task = -1;
-                }
-                return rt_task;
-        }
-        else {
+        if (rt_task == 0) {
                 /* we are the real-time task 
                  * launch task and die when it is done
                  */             
-                
+                rt_task = getpid();             
+                ret = setup(rt_task, setup_arg);
+                if (ret < 0)
+                        tperrorx("could not setup task parameters");
+                ret = task_mode(LITMUS_RT_TASK);
+                if (ret < 0)
+                        tperrorx("could not become real-time task");
                 exit(rt_prog(rt_arg));
         }
+
+        return rt_task;
 }
 
 struct create_rt_param {