1 files changed, 10 insertions, 0 deletions

diff --git a/pipe.c b/pipe.c
index 3aed4e9..3975244 100644
--- a/pipe.c
+++ b/pipe.c
@@ -5,6 +5,7 @@
 #include "proc.h"
 #include "defs.h"
 #include "fd.h"
+#include "spinlock.h"
 
 #define PIPESIZE 512
 
@@ -13,6 +14,7 @@ struct pipe {
   int writeopen; // write fd is still open
   int writep; // next index to write
   int readp;  // next index to read
+  struct spinlock lock;
   char data[PIPESIZE];
 };
 
@@ -32,6 +34,7 @@ pipe_alloc(struct fd **fd1, struct fd **fd2)
   p->writeopen = 1;
   p->writep = 0;
   p->readp = 0;
+  memset(&p->lock, 0, sizeof(p->lock));
   (*fd1)->type = FD_PIPE;
   (*fd1)->readable = 1;
   (*fd1)->writeable = 0;
@@ -74,16 +77,21 @@ pipe_write(struct pipe *p, char *addr, int n)
 {
   int i;
 
+  acquire(&p->lock);
+
   for(i = 0; i < n; i++){
     while(((p->writep + 1) % PIPESIZE) == p->readp){
       if(p->readopen == 0)
         return -1;
+      release(&p->lock);
       wakeup(&p->readp);
       sleep(&p->writep);
+      acquire(&p->lock);
     }
     p->data[p->writep] = addr[i];
     p->writep = (p->writep + 1) % PIPESIZE;
   }
+  release(&p->lock);
   wakeup(&p->readp);
   return i;
 }
@@ -99,12 +107,14 @@ pipe_read(struct pipe *p, char *addr, int n)
     sleep(&p->readp);
   }
 
+  acquire(&p->lock);
   for(i = 0; i < n; i++){
     if(p->readp == p->writep)
       break;
     addr[i] = p->data[p->readp];
     p->readp = (p->readp + 1) % PIPESIZE;
   }
+  release(&p->lock);
   wakeup(&p->writep);
   return i;
 }