A few now unused DOC

kernel/pipe.c

@@ -88,13 +88,13 @@ pipewrite(struct pipe *pi, uint64 addr, int n)
         return -1;
       }
       wakeup(&pi->nread);
-      sleep(&pi->nwrite, &pi->lock);  //DOC: pipewrite-sleep
+      sleep(&pi->nwrite, &pi->lock);
     }
     if(copyin(pr->pagetable, &ch, addr + i, 1) == -1)
       break;
     pi->data[pi->nwrite++ % PIPESIZE] = ch;
   }
-  wakeup(&pi->nread);  //DOC: pipewrite-wakeup1
+  wakeup(&pi->nread);
   release(&pi->lock);
   return n;
 }

kernel/proc.c

@@ -476,7 +476,7 @@ void
 yield(void)
 {
   struct proc *p = myproc();
-  acquire(&p->lock);  //DOC: yieldlock
+  acquire(&p->lock);
   p->state = RUNNABLE;
   sched();
   release(&p->lock);
@@ -531,7 +531,7 @@ sleep(void *chan, struct spinlock *lk)
   p->chan = 0;
 
   // Reacquire original lock.
-  if(lk != &p->lock){  //DOC: sleeplock2
+  if(lk != &p->lock){
     release(&p->lock);
     acquire(lk);
   }