Change addrun to set p->state = RUNNABLE

eca599b3 · Silas Boyd-Wickizer · 87b199ef · eca599b3 · eca599b3 · eca599b3
--- a/condvar.c
+++ b/condvar.c
@@ -21,7 +21,6 @@ wakeup(struct proc *p)
  LIST_REMOVE(p, cv_waiters);
  p->oncv = 0;
  addrun(p);
-  p->state = RUNNABLE;
 }

 void

--- a/gc.c
+++ b/gc.c
@@ -315,7 +315,6 @@ initgc(void)
    gcp->cpuid = c;
    gcp->cpu_pin = 1;
    acquire(&gcp->lock);
-    gcp->state = RUNNABLE;
    addrun(gcp);
    release(&gcp->lock);
  }

--- a/kernel.h
+++ b/kernel.h
@@ -247,7 +247,6 @@ void            sched(void);
 void            userinit(void);
 int             wait(void);
 void            yield(void);
-void            migrate(struct proc *);
 struct proc*    threadalloc(void (*fn)(void*), void *arg);

 // prof.c

--- a/net.c
+++ b/net.c
@@ -106,7 +106,6 @@ start_timer(struct timer_thread *t, void (*func)(void),

  acquire(&p->lock);
  safestrcpy(p->name, name, sizeof(p->name));
-  p->state = RUNNABLE;
  addrun(p);
  release(&p->lock);
 }
@@ -262,7 +261,6 @@ initnet(void)

  acquire(&t->lock);
  safestrcpy(t->name, "initnet", sizeof(t->name));
-  t->state = RUNNABLE;
  addrun(t);
  release(&t->lock);
 }

--- a/proc.c
+++ b/proc.c
@@ -61,39 +61,38 @@ yield(void)
  release(&myproc()->lock);
 }

-void
+static int
 migrate(struct proc *p)
 {
+  // p should not be running, or be on a runqueue, or be myproc()
  int c;

+  if (p == myproc())
+    panic("migrate: myproc");
+
  for (c = 0; c < NCPU; c++) {
    if (c == mycpu()->id)
      continue;
    if (idle[c]) {    // OK if there is a race
      acquire(&p->lock);
-      if (p->state != RUNNABLE || p->cpu_pin) {
-	release(&p->lock);
-	continue;
-      }
-
-      if (sched_debug)
-	cprintf("cpu%d: migrate %d to %d\n", mycpu()->id, p->pid, c);
+      if (p->state == RUNNING)
+        panic("migrate: pid %u name %s is running",
+              p->pid, p->name);
+      if (p->cpu_pin)
+        panic("migrate: pid %u name %s is pinned",
+              p->pid, p->name);

-      delrun(p);
      p->curcycles = 0;
      p->cpuid = c;
      addrun(p);
      idle[c] = 0;

-      if (p == myproc()) {
-        myproc()->state = RUNNABLE;
-	sched();
-      }
-
      release(&p->lock);
-      return;
+      return 0;
    }
  }
+
+  return -1;
 }

 // A fork child's very first scheduling by scheduler()
@@ -268,7 +267,6 @@ inituser(void)
  p->cwd = NULL; // forkret will fix in the process's context
  acquire(&p->lock);
  addrun(p);
-  p->state = RUNNABLE;
  release(&p->lock);
 }

@@ -327,7 +325,7 @@ scheduler(void)
    if (p) {
      acquire(&p->lock);
      if (p->state != RUNNABLE) {
-	release(&p->lock);
+        release(&p->lock);
      } else {
        if (idle[mycpu()->id])
 	  idle[mycpu()->id] = 0;
@@ -593,12 +591,12 @@ fork(int flags)
  SLIST_INSERT_HEAD(&myproc()->childq, np, child_next);
  release(&myproc()->lock);

-  acquire(&np->lock);
-  addrun(np);
-  np->state = RUNNABLE;
-  release(&np->lock);
-
-  migrate(np);
+  if (migrate(np)) {
+    acquire(&np->lock);
+    np->cpuid = mycpu()->id;
+    addrun(np);
+    release(&np->lock);
+  }

  //  cprintf("%d: fork done (pid %d)\n", myproc()->pid, pid);
  return pid;

--- a/sched.c
+++ b/sched.c
@@ -29,6 +29,8 @@ addrun(struct proc *p)
  // Always called with p->lock held
  struct runq *q;

+  p->state = RUNNABLE;
+
  q = &runq[p->cpuid];
  acquire(&q->lock);
  STAILQ_INSERT_HEAD(&q->q, p, runqlink);