From e45f3adbd21cd675c38b1d29394ec60b9cec2e33 Mon Sep 17 00:00:00 2001
From: Ben Pfaff <blp@cs.stanford.edu>
Date: Sat, 11 Sep 2004 23:27:29 +0000
Subject: [PATCH] Do console locking. Rename printf.c to console.c to better
 explain its function. Move puts() from lib to lib/{user,kernel} so it can
 take console lock.

---
 src/lib/kernel/console.c             | 93 ++++++++++++++++++++++++++++
 src/lib/kernel/console.h             |  6 ++
 src/lib/kernel/printf.c              | 41 ------------
 src/lib/stdio.c                      | 11 ----
 src/lib/user/{printf.c => console.c} | 12 ++++
 5 files changed, 111 insertions(+), 52 deletions(-)
 create mode 100644 src/lib/kernel/console.c
 create mode 100644 src/lib/kernel/console.h
 delete mode 100644 src/lib/kernel/printf.c
 rename src/lib/user/{printf.c => console.c} (86%)

diff --git a/src/lib/kernel/console.c b/src/lib/kernel/console.c
new file mode 100644
index 0000000..7ce9cbf
--- /dev/null
+++ b/src/lib/kernel/console.c
@@ -0,0 +1,93 @@
+#include <stdarg.h>
+#include <stdio.h>
+#include "devices/serial.h"
+#include "devices/vga.h"
+#include "threads/interrupt.h"
+#include "threads/synch.h"
+
+static void vprintf_helper (char, void *);
+static void putchar_unlocked (uint8_t c);
+
+/* The console lock.
+   Both the vga and serial layers do their own locking, so it's
+   safe to call them at any time.
+   But this lock is useful to prevent simultaneous printf() calls
+   from mixing their output, which looks confusing. */
+static struct lock console_lock;
+
+void
+console_init (void) 
+{
+  lock_init (&console_lock, "console");
+}
+
+/* The standard vprintf() function,
+   which is like printf() but uses a va_list.
+   Writes its output to both vga display and serial port. */
+int
+vprintf (const char *format, va_list args) 
+{
+  int char_cnt = 0;
+
+  if (!intr_context ())
+    lock_acquire (&console_lock);
+
+  __vprintf (format, args, vprintf_helper, &char_cnt);
+
+  if (!intr_context ())
+    lock_release (&console_lock);
+
+  return char_cnt;
+}
+
+/* Writes string S to the console, followed by a new-line
+   character. */
+int
+puts (const char *s) 
+{
+  if (!intr_context ())
+    lock_acquire (&console_lock);
+
+  while (*s != '\0')
+    putchar_unlocked (*s++);
+  putchar_unlocked ('\n');
+
+  if (!intr_context ())
+    lock_release (&console_lock);
+
+  return 0;
+}
+
+/* Writes C to the vga display and serial port. */
+int
+putchar (int c) 
+{
+  if (!intr_context ())
+    lock_acquire (&console_lock);
+
+  putchar_unlocked (c);
+
+  if (!intr_context ())
+    lock_release (&console_lock);
+
+  return c;
+}
+
+/* Helper function for vprintf(). */
+static void
+vprintf_helper (char c, void *char_cnt_) 
+{
+  int *char_cnt = char_cnt_;
+  (*char_cnt)++;
+  putchar_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) 
+{
+  serial_putc (c);
+  vga_putc (c);
+}
diff --git a/src/lib/kernel/console.h b/src/lib/kernel/console.h
new file mode 100644
index 0000000..6e5b41b
--- /dev/null
+++ b/src/lib/kernel/console.h
@@ -0,0 +1,6 @@
+#ifndef __LIB_KERNEL_CONSOLE_H
+#define __LIB_KERNEL_CONSOLE_H
+
+void console_init (void);
+
+#endif /* lib/kernel/console.h */
diff --git a/src/lib/kernel/printf.c b/src/lib/kernel/printf.c
deleted file mode 100644
index c139966..0000000
--- a/src/lib/kernel/printf.c
+++ /dev/null
@@ -1,41 +0,0 @@
-#include <stdarg.h>
-#include <stdio.h>
-#include "devices/serial.h"
-#include "devices/vga.h"
-#include "threads/interrupt.h"
-
-static void vprintf_helper (char, void *);
-
-/* The standard vprintf() function,
-   which is like printf() but uses a va_list.
-   Writes its output to both vga display and serial port. */
-int
-vprintf (const char *format, va_list args) 
-{
-  enum intr_level old_level;
-  int char_cnt = 0;
-
-  old_level = intr_disable ();
-  __vprintf (format, args, vprintf_helper, &char_cnt);
-  intr_set_level (old_level);
-
-  return char_cnt;
-}
-
-/* Helper function for vprintf(). */
-static void
-vprintf_helper (char c, void *char_cnt_) 
-{
-  int *char_cnt = char_cnt_;
-  (*char_cnt)++;
-  putchar (c);
-}
-
-/* Writes C to the vga display and serial port. */
-int
-putchar (int c) 
-{
-  serial_putc (c);
-  vga_putc (c);
-  return c;
-}
diff --git a/src/lib/stdio.c b/src/lib/stdio.c
index 95dfdbe..d223d10 100644
--- a/src/lib/stdio.c
+++ b/src/lib/stdio.c
@@ -552,17 +552,6 @@ __printf (const char *format,
   __vprintf (format, args, output, aux);
   va_end (args);
 }
-
-/* Writes string S to the console, followed by a new-line
-   character. */
-int
-puts (const char *s) 
-{
-  while (*s != '\0')
-    putchar (*s++);
-  putchar ('\n');
-  return 0;
-}
 
 /* Dumps the SIZE bytes in BUFFER to the console as hex bytes
    arranged 16 per line.  If ASCII is true then the corresponding
diff --git a/src/lib/user/printf.c b/src/lib/user/console.c
similarity index 86%
rename from src/lib/user/printf.c
rename to src/lib/user/console.c
index 6466e54..709a5c8 100644
--- a/src/lib/user/printf.c
+++ b/src/lib/user/console.c
@@ -41,6 +41,18 @@ vprintf_helper (char c, void *aux_)
   aux->char_cnt++;
 }
 
+/* Writes string S to the console, followed by a new-line
+   character. */
+int
+puts (const char *s) 
+{
+  while (*s != '\0')
+    putchar (*s++);
+  putchar ('\n');
+
+  return 0;
+}
+
 /* Writes C to the console. */
 int
 putchar (int c) 
-- 
2.30.2