The scheduler loop no longer needs to hold the next proc's lock

a7db852c · Silas Boyd-Wickizer · 66ad4934 · a7db852c · a7db852c · a7db852c
--- a/kernel/condvar.cc
+++ b/kernel/condvar.cc
@@ -94,7 +94,6 @@ void cv_sleepto(struct condvar *cv, struct spinlock *lk, u64 timeout)
  release(&cv->lock);

  sched();
-  release(&myproc()->lock);

  // Reacquire original lock.
  acquire(lk);

--- a/kernel/idle.cc
+++ b/kernel/idle.cc
@@ -37,10 +37,8 @@ idleloop(void)

    struct proc *p = schednext();
    if (p) {
-      acquire(&p->lock);
      if (get_proc_state(p) != RUNNABLE) {
        panic("Huh?");
-        release(&p->lock);
      } else {
        if (idle[mycpu()->id])
 	  idle[mycpu()->id] = 0;

--- a/kernel/proc.cc
+++ b/kernel/proc.cc
@@ -64,7 +64,6 @@ yield(void)
  acquire(&myproc()->lock);  //DOC: yieldlock
  set_proc_state(myproc(), RUNNABLE);
  sched();
-  release(&myproc()->lock);
 }


@@ -73,9 +72,6 @@ yield(void)
 void
 forkret(void)
 {
-  // Still holding proc->lock from scheduler.
-  release(&myproc()->lock);
-
  // Just for the first process. can't do it earlier
  // b/c file system code needs a process context
  // in which to call cv_sleep().
@@ -527,7 +523,6 @@ wait(void)
 void
 threadhelper(void (*fn)(void *), void *arg)
 {
-  release(&myproc()->lock); // initially held by scheduler
  mtstart(fn, myproc());
  fn(arg);
  exit();