Switch to new np-section protocol.

Everything is in one 32-bit word now.

3 files changed, 18 insertions, 3 deletions

diff --git a/include/internal.h b/include/internal.h
index 07253b7..f30ce61 100644
--- a/include/internal.h
+++ b/include/internal.h
@@ -18,8 +18,13 @@ int __launch_rt_task(rt_fn_t rt_prog, void *rt_arg,
         }
 
 
+/* taken from the kernel */
+
 #define likely(x)   __builtin_expect((x), 1)
 #define unlikely(x) __builtin_expect((x), 0)
 
+#define BUILD_BUG_ON_ZERO(e) (sizeof(struct { int:-!!(e); }))
+#define BUILD_BUG_ON(condition) ((void)BUILD_BUG_ON_ZERO(condition))
+
 #endif
 
diff --git a/include/litmus.h b/include/litmus.h
index 40ee124..4c85d28 100644
--- a/include/litmus.h
+++ b/include/litmus.h
@@ -96,6 +96,7 @@ task_class_t str2class(const char* str);
 /* non-preemptive section support */
 void enter_np(void);
 void exit_np(void);
+int  requested_to_preempt(void);
 
 /* task system support */
 int wait_for_ts_release(void);
diff --git a/src/kernel_iface.c b/src/kernel_iface.c
index 1426795..33d56df 100644
--- a/src/kernel_iface.c
+++ b/src/kernel_iface.c
@@ -43,6 +43,8 @@ int init_kernel_iface(void)
         int err = 0;
         long page_size = sysconf(_SC_PAGESIZE);
 
+        BUILD_BUG_ON(sizeof(union np_flag) != sizeof(uint32_t));
+
         err = map_file(LITMUS_CTRL_DEVICE, (void**) &ctrl_page, CTRL_PAGES * page_size);
         if (err) {
                 fprintf(stderr, "%s: cannot open LITMUS^RT control page (%m)\n",
@@ -55,7 +57,7 @@ int init_kernel_iface(void)
 void enter_np(void)
 {
         if (likely(ctrl_page != NULL) || init_kernel_iface() == 0)
-                ctrl_page->np_flag++;
+                ctrl_page->sched.np.flag++;
         else
                 fprintf(stderr, "enter_np: control page not mapped!\n");
 }
@@ -63,14 +65,21 @@ void enter_np(void)
 
 void exit_np(void)
 {
-        if (likely(ctrl_page != NULL) && --ctrl_page->np_flag == 0) {
+        if (likely(ctrl_page != NULL) &&
+            ctrl_page->sched.np.flag &&
+            !(--ctrl_page->sched.np.flag)) {
                 /* became preemptive, let's check for delayed preemptions */
                 __sync_synchronize();
-                if (ctrl_page->delayed_preemption)
+                if (ctrl_page->sched.np.preempt)
                         sched_yield();
         }
 }
 
+int requested_to_preempt(void)
+{
+        return (likely(ctrl_page != NULL) && ctrl_page->sched.np.preempt);
+}
+
 /* init and return a ptr to the control page for
  * preemption and migration overhead analysis
  *