X-Git-Url: https://codewiz.org/gitweb?a=blobdiff_plain;f=bertos%2Fkern%2Fpreempt.c;h=cde336510ee0e36cf6644f9bc5f92e5f0e74dc98;hb=e6339d49f97766bd1825d6f07ec44ec864d5ebfe;hp=7ecd481d0cdf57c6d4c3679fc4ccfa43f5cc794e;hpb=cfa8814ca45e8bae9b36713bc534ecb581834016;p=bertos.git

diff --git a/bertos/kern/preempt.c b/bertos/kern/preempt.c
index 7ecd481d..cde33651 100644
--- a/bertos/kern/preempt.c
+++ b/bertos/kern/preempt.c
@@ -41,43 +41,18 @@
 #include <kern/irq.h>
 #include <kern/monitor.h>
 #include <cpu/frame.h> // CPU_IDLE
+#include <cpu/irq.h>   // IRQ_DISABLE()...
 #include <drv/timer.h>
 #include <cfg/module.h>
 
 
+int preempt_forbid_cnt;
 
 Timer preempt_timer;
 
-/**
- * Disable preemptive task switching.
- *
- * The scheduler maintains a per-process nesting counter.  Task switching is
- * effectively re-enabled only when the number of calls to proc_permit()
- * matches the number of calls to proc_forbid().
- *
- * Calling functions that could sleep while task switching is disabled
- * is dangerous, although supported.  Preemptive task switching is
- * resumed while the process is sleeping and disabled again as soon as
- * it wakes up again.
- *
- * \sa proc_permit()
- */
-void proc_forbid(void)
-{
-	/* No need to protect against interrupts here. */
-	++CurrentProcess->forbid_cnt;
-}
 
-/**
- * Re-enable preemptive task switching.
- *
- * \sa proc_forbid()
- */
-void proc_permit(void)
-{
-	/* No need to protect against interrupts here. */
-	--CurrentProcess->forbid_cnt;
-}
+// fwd decl from idle.c
+void idle_init(void);
 
 
 void proc_preempt(void)
@@ -97,12 +72,15 @@ void proc_preempt(void)
 
 void proc_preempt_timer(UNUSED_ARG(void *, param))
 {
+	/* Abort if task preemption is disabled */
+	if (preempt_forbid_cnt)
+		return;
+
 	IRQ_DISABLE;
 /*
 	if (!CurrentProcess->forbid_cnt)
 	{
 		TRACEMSG("preempting %p:%s", CurrentProcess, CurrentProcess->monitor.name);
-		LIST_ASSERT_VALID(&ProcReadyList);
 		SCHED_ENQUEUE(CurrentProcess);
 		proc_preempt();
 	}
@@ -115,7 +93,13 @@ void proc_preempt_timer(UNUSED_ARG(void *, param))
 
 void proc_schedule(void)
 {
-	TRACE;
+	ATOMIC(LIST_ASSERT_VALID(&ProcReadyList));
+	TRACEMSG("%p:%s", CurrentProcess, proc_currentName());
+	ATOMIC(LIST_ASSERT_VALID(&ProcReadyList));
+
+	/* Sleeping with IRQs disabled or preemption forbidden is illegal */
+	ASSERT_IRQ_ENABLED();
+	ASSERT(preempt_forbid_cnt == 0);
 
 	// Will invoke proc_preempt() in interrupt context
 	kill(0, SIGUSR1);
@@ -123,14 +107,13 @@ void proc_schedule(void)
 
 void proc_yield(void)
 {
-	TRACE;
+	TRACEMSG("%p:%s", CurrentProcess, proc_currentName());
 
-	ASSERT_IRQ_ENABLED();
 	IRQ_DISABLE;
 	SCHED_ENQUEUE(CurrentProcess);
-	LIST_ASSERT_VALID(&ProcReadyList);
-	proc_schedule();
 	IRQ_ENABLE;
+
+	proc_schedule();
 }
 
 void proc_entry(void (*user_entry)(void))
@@ -139,29 +122,6 @@ void proc_entry(void (*user_entry)(void))
 	proc_exit();
 }
 
-
-static cpustack_t idle_stack[CONFIG_PROC_DEFSTACKSIZE / sizeof(cpustack_t)];
-
-/*
- * The idle process
- *
- * This process never dies and never sleeps.  It's also quite apathic
- * and a bit antisocial.
- *
- * Having an idle process costs some stack space, but simplifies the
- * interrupt-driven preemption logic because there is always a user
- * context to which we can return.
- */
-static NORETURN void idle(void)
-{
-	for (;;)
-	{
-		TRACE;
-		monitor_report();
-		proc_yield(); // FIXME: CPU_IDLE
-	}
-}
-
 void preempt_init(void)
 {
 	MOD_CHECK(irq);
@@ -173,5 +133,5 @@ void preempt_init(void)
 	timer_setDelay(&preempt_timer, CONFIG_KERN_QUANTUM);
 	timer_add(&preempt_timer);
 
-	proc_new(idle, NULL, sizeof(idle_stack), idle_stack);
+	idle_init();
 }