Clarify comment.

[pintos-anon] / solutions / p4.patch

diff --git a/solutions/p4.patch b/solutions/p4.patch
index d481c701d3ab90d60be361cc22569d12a3530608..82a51e17a4e8811bf1ef322cee0c2ce3e145b9e4 100644 (file)
--- a/solutions/p4.patch
+++ b/solutions/p4.patch
@@ -2566,7 +2566,7 @@ diff -u src/userprog/process.c~ src/userprog/process.c
  
    ASSERT (file != NULL);
    ASSERT (phdr != NULL);
-@@ -332,69 +458,129 @@ load_segment (struct file *file, const s
+@@ -332,73 +458,129 @@ load_segment (struct file *file, const s
        || start == 0)
      return false; 
  
@@ -2709,8 +2709,12 @@ diff -u src/userprog/process.c~ src/userprog/process.c
  }
  
 -/* Adds a mapping from user virtual address UPAGE to kernel
--   virtual address KPAGE to the page table.  Fails if UPAGE is
--   already mapped or if memory allocation fails. */
+-   virtual address KPAGE to the page table.
+-   UPAGE must not already be mapped.
+-   KPAGE should probably be a page obtained from the user pool
+-   with palloc_get_page().
+-   Returns true on success, false if UPAGE is already mapped or
+-   if memory allocation fails. */
 +/* Create a minimal stack for T by mapping a page at the
 +   top of user virtual memory.  Fills in the page using CMD_LINE
 +   and sets *ESP to the stack pointer. */
@@ -3547,7 +3551,7 @@ diff -u src/vm/frame.h~ src/vm/frame.h
 diff -u src/vm/page.c~ src/vm/page.c
 --- src/vm/page.c~ 1969-12-31 16:00:00.000000000 -0800
 +++ src/vm/page.c 2005-06-16 15:09:31.000000000 -0700
-@@ -0,0 +1,297 @@
+@@ -0,0 +1,294 @@
 +#include "vm/page.h"
 +#include <stdio.h>
 +#include <string.h>
@@ -3562,29 +3566,26 @@ diff -u src/vm/page.c~ src/vm/page.c
 +/* Maximum size of process stack, in bytes. */
 +#define STACK_MAX (1024 * 1024)
 +
++/* Destroys a page, which must be in the current process's
++   page table.  Used as a callback for hash_destroy(). */
++static void
++destroy_page (struct hash_elem *p_, void *aux UNUSED)
++{
++  struct page *p = hash_entry (p_, struct page, hash_elem);
++  frame_lock (p);
++  if (p->frame)
++    frame_free (p->frame);
++  free (p);
++}
++
++
 +/* Destroys the current process's page table. */
 +void
 +page_exit (void) 
 +{
-+  struct hash *h;
-+  struct hash_iterator i;
-+
-+  h = thread_current ()->pages;
-+  if (h == NULL)
-+    return;
-+  
-+  hash_first (&i, h);
-+  hash_next (&i);
-+  while (hash_cur (&i))
-+    {
-+      struct page *p = hash_entry (hash_cur (&i), struct page, hash_elem);
-+      hash_next (&i);
-+      frame_lock (p);
-+      if (p->frame)
-+        frame_free (p->frame);
-+      free (p);
-+    }
-+  hash_destroy (h);
++  struct hash *h = thread_current ()->pages;
++  if (h != NULL)
++    hash_destroy (h, destroy_page);
 +}
 +
 +/* Returns the page containing the given virtual ADDRESS,