Eliminate race condition in console_print_stats() found by Sorav's

[pintos-anon] / src / lib / kernel / console.c

diff --git a/src/lib/kernel/console.c b/src/lib/kernel/console.c
index 865b13b2cd810b0805acead8ec9f4e3e038f609a..176dd0688dc5717919b06e59d4a784f0d24c1f64 100644 (file)
--- a/src/lib/kernel/console.c
+++ b/src/lib/kernel/console.c
@@ -7,7 +7,7 @@
 #include "threads/synch.h"
 
 static void vprintf_helper (char, void *);
-static void putchar_unlocked (uint8_t c);
+static void put_char_unlocked (uint8_t c);
 
 /* The console lock.
    Both the vga and serial layers do their own locking, so it's
@@ -31,7 +31,7 @@ static struct lock console_lock;
    intr_handler()       - timer interrupt
    intr_set_level()
    serial_putc()
-   putchar_unlocked()
+   put_char_unlocked()
    putbuf()
    sys_write()          - one process writing to the console
    syscall_handler()
@@ -52,13 +52,6 @@ console_init (void)
   lock_init (&console_lock);
 }
 
-/* Prints console statistics. */
-void
-console_print_stats (void) 
-{
-  printf ("Console: %lld characters output\n", write_cnt);
-}
-
 /* Acquires the console lock. */
 static void
 acquire_console (void) 
@@ -93,6 +86,15 @@ console_locked_by_current_thread (void)
   return intr_context () || lock_held_by_current_thread (&console_lock);
 }
 
+/* Prints console statistics. */
+void
+console_print_stats (void) 
+{
+  acquire_console ();
+  printf ("Console: %lld characters output\n", write_cnt);
+  release_console ();
+}
+
 /* The standard vprintf() function,
    which is like printf() but uses a va_list.
    Writes its output to both vga display and serial port. */
@@ -115,8 +117,8 @@ puts (const char *s)
 {
   acquire_console ();
   while (*s != '\0')
-    putchar_unlocked (*s++);
-  putchar_unlocked ('\n');
+    put_char_unlocked (*s++);
+  put_char_unlocked ('\n');
   release_console ();
 
   return 0;
@@ -128,7 +130,7 @@ putbuf (const char *buffer, size_t n)
 {
   acquire_console ();
   while (n-- > 0)
-    putchar_unlocked (*buffer++);
+    put_char_unlocked (*buffer++);
   release_console ();
 }
 
@@ -137,7 +139,7 @@ int
 putchar (int c) 
 {
   acquire_console ();
-  putchar_unlocked (c);
+  put_char_unlocked (c);
   release_console ();
   
   return c;
@@ -149,14 +151,14 @@ vprintf_helper (char c, void *char_cnt_)
 {
   int *char_cnt = char_cnt_;
   (*char_cnt)++;
-  putchar_unlocked (c);
+  put_char_unlocked (c);
 }
 
 /* Writes C to the vga display and serial port.
    The caller has already acquired the console lock if
    appropriate. */
 static void
-putchar_unlocked (uint8_t c) 
+put_char_unlocked (uint8_t c) 
 {
   ASSERT (console_locked_by_current_thread ());
   write_cnt++;