CM3: kernel preemption.

[bertos.git] / bertos / kern / proc.c

diff --git a/bertos/kern/proc.c b/bertos/kern/proc.c
index 794918a54447f1f4a85dcfc78d1c6119ba729cc8..a18fc40498d52e85e198ee54e5e13a1e90e2c49e 100644 (file)
--- a/bertos/kern/proc.c
+++ b/bertos/kern/proc.c
@@ -60,6 +60,8 @@
 
 #include <string.h>           /* memset() */
 
+#define PROC_SIZE_WORDS (ROUND_UP2(sizeof(Process), sizeof(cpu_stack_t)) / sizeof(cpu_stack_t))
+
 /*
  * The scheduer tracks ready processes by enqueuing them in the
  * ready list.
@@ -83,7 +85,7 @@ static struct Process main_process;
 /**
  * Local heap dedicated to allocate the memory used by the processes.
  */
-static HEAP_DEFINE_BUF(heap_buf, KERN_MINSTACKSIZE * 128);
+static HEAP_DEFINE_BUF(heap_buf, CONFIG_KERN_HEAP_SIZE);
 static Heap proc_heap;
 
 /*
@@ -137,11 +139,6 @@ void proc_init(void)
        monitor_init();
        monitor_add(current_process, "main");
 #endif
-
-#if CONFIG_KERN_PREEMPT
-       preempt_init();
-#endif
-
        MOD_INIT(proc);
 }
 
@@ -163,8 +160,10 @@ static void proc_freeZombies(void)
                        return;
 
                if (proc->flags & PF_FREESTACK)
+               {
                        PROC_ATOMIC(heap_freemem(&proc_heap, proc->stack_base,
-                                       proc->stack_size));
+                               proc->stack_size + PROC_SIZE_WORDS * sizeof(cpu_stack_t)));
+               }
        }
 }
 
@@ -206,7 +205,6 @@ static void proc_addZombie(Process *proc)
 struct Process *proc_new_with_name(UNUSED_ARG(const char *, name), void (*entry)(void), iptr_t data, size_t stack_size, cpu_stack_t *stack_base)
 {
        Process *proc;
-       const size_t PROC_SIZE_WORDS = ROUND_UP2(sizeof(Process), sizeof(cpu_stack_t)) / sizeof(cpu_stack_t);
        LOG_INFO("name=%s", name);
 #if CONFIG_KERN_HEAP
        bool free_stack = false;
@@ -422,11 +420,41 @@ void proc_exit(void)
        ASSERT(0);
 }
 
-
 /**
- * Get the pointer to the user data of the current process
+ * Call the scheduler and eventually replace the current running process.
  */
-iptr_t proc_currentUserData(void)
+void proc_schedule(void)
 {
-       return current_process->user_data;
+       Process *old_process = current_process;
+
+       IRQ_ASSERT_DISABLED();
+
+       /* Poll on the ready queue for the first ready process */
+       LIST_ASSERT_VALID(&proc_ready_list);
+       while (!(current_process = (struct Process *)list_remHead(&proc_ready_list)))
+       {
+               /*
+                * Make sure we physically reenable interrupts here, no matter what
+                * the current task status is. This is important because if we
+                * are idle-spinning, we must allow interrupts, otherwise no
+                * process will ever wake up.
+                *
+                * During idle-spinning, an interrupt can occur and it may
+                * modify \p proc_ready_list. To ensure that compiler reload this
+                * variable every while cycle we call CPU_MEMORY_BARRIER.
+                * The memory barrier ensure that all variables used in this context
+                * are reloaded.
+                * \todo If there was a way to write sig_wait() so that it does not
+                * disable interrupts while waiting, there would not be any
+                * reason to do this.
+                */
+               IRQ_ENABLE;
+               CPU_IDLE;
+               MEMORY_BARRIER;
+               IRQ_DISABLE;
+       }
+       if (CONTEXT_SWITCH_FROM_ISR())
+               proc_switchTo(current_process, old_process);
+       /* This RET resumes the execution on the new process */
+       LOG_INFO("resuming %p:%s\n", current_process, proc_currentName());
 }