swtch saves callee-saved registers

swtch idles on per-CPU stack, not on calling process's stack
fix pipe bugs
usertest.c tests pipes, fork, exit, close

1 files changed, 12 insertions, 2 deletions

diff --git a/pipe.c b/pipe.c
index 9a81e0b..3aed4e9 100644
--- a/pipe.c
+++ b/pipe.c
@@ -28,6 +28,10 @@ pipe_alloc(struct fd **fd1, struct fd **fd2)
     goto oops;
   if((p = (struct pipe *) kalloc(PAGE)) == 0)
     goto oops;
+  p->readopen = 1;
+  p->writeopen = 1;
+  p->writep = 0;
+  p->readp = 0;
   (*fd1)->type = FD_PIPE;
   (*fd1)->readable = 1;
   (*fd1)->writeable = 0;
@@ -54,10 +58,13 @@ pipe_alloc(struct fd **fd1, struct fd **fd2)
 void
 pipe_close(struct pipe *p, int writeable)
 {
-  if(writeable)
+  if(writeable){
     p->writeopen = 0;
-  else
+    wakeup(&p->readp);
+  } else {
     p->readopen = 0;
+    wakeup(&p->writep);
+  }
   if(p->readopen == 0 && p->writeopen == 0)
     kfree((char *) p, PAGE);
 }
@@ -71,11 +78,13 @@ pipe_write(struct pipe *p, char *addr, int n)
     while(((p->writep + 1) % PIPESIZE) == p->readp){
       if(p->readopen == 0)
         return -1;
+      wakeup(&p->readp);
       sleep(&p->writep);
     }
     p->data[p->writep] = addr[i];
     p->writep = (p->writep + 1) % PIPESIZE;
   }
+  wakeup(&p->readp);
   return i;
 }
 
@@ -96,5 +105,6 @@ pipe_read(struct pipe *p, char *addr, int n)
     addr[i] = p->data[p->readp];
     p->readp = (p->readp + 1) % PIPESIZE;
   }
+  wakeup(&p->writep);
   return i;
 }