thread: Do not disable interrupts unnecessarily while initializing stack.

[pintos-anon] / src / threads / synch.c

diff --git a/src/threads/synch.c b/src/threads/synch.c
index 5ec14abf8d4dfa11851e02917a1d030540a560f0..317c68ad501301538f47a697df7a8eaf02d4e077 100644 (file)
--- a/src/threads/synch.c
+++ b/src/threads/synch.c
@@ -55,8 +55,8 @@ sema_init (struct semaphore *sema, unsigned value)
 
    This function may sleep, so it must not be called within an
    interrupt handler.  This function may be called with
 
    This function may sleep, so it must not be called within an
    interrupt handler.  This function may be called with

-   interrupts disabled, but interrupts will be turned back on if
-   we need to sleep. */
+   interrupts disabled, but if it sleeps then the next scheduled
+   thread will probably turn interrupts back on. */

 void
 sema_down (struct semaphore *sema) 
 {
 void
 sema_down (struct semaphore *sema) 
 {


@@ -192,16 +192,12 @@ lock_init (struct lock *lock)
 void
 lock_acquire (struct lock *lock)
 {
 void
 lock_acquire (struct lock *lock)
 {

-  enum intr_level old_level;
-

   ASSERT (lock != NULL);
   ASSERT (!intr_context ());
   ASSERT (!lock_held_by_current_thread (lock));
 
   ASSERT (lock != NULL);
   ASSERT (!intr_context ());
   ASSERT (!lock_held_by_current_thread (lock));
 

-  old_level = intr_disable ();

   sema_down (&lock->semaphore);
   lock->holder = thread_current ();
   sema_down (&lock->semaphore);
   lock->holder = thread_current ();

-  intr_set_level (old_level);

 }
 
 /* Tries to acquires LOCK and returns true if successful or false
 }
 
 /* Tries to acquires LOCK and returns true if successful or false


@@ -213,18 +209,14 @@ lock_acquire (struct lock *lock)
 bool
 lock_try_acquire (struct lock *lock)
 {
 bool
 lock_try_acquire (struct lock *lock)
 {

-  enum intr_level old_level;

   bool success;
 
   ASSERT (lock != NULL);
   ASSERT (!lock_held_by_current_thread (lock));
 
   bool success;
 
   ASSERT (lock != NULL);
   ASSERT (!lock_held_by_current_thread (lock));
 

-  old_level = intr_disable ();

   success = sema_try_down (&lock->semaphore);
   if (success)
     lock->holder = thread_current ();
   success = sema_try_down (&lock->semaphore);
   if (success)
     lock->holder = thread_current ();

-  intr_set_level (old_level);
-

   return success;
 }
 
   return success;
 }
 


@@ -236,15 +228,11 @@ lock_try_acquire (struct lock *lock)
 void
 lock_release (struct lock *lock) 
 {
 void
 lock_release (struct lock *lock) 
 {

-  enum intr_level old_level;
-

   ASSERT (lock != NULL);
   ASSERT (lock_held_by_current_thread (lock));
 
   ASSERT (lock != NULL);
   ASSERT (lock_held_by_current_thread (lock));
 

-  old_level = intr_disable ();

   lock->holder = NULL;
   sema_up (&lock->semaphore);
   lock->holder = NULL;
   sema_up (&lock->semaphore);

-  intr_set_level (old_level);

 }
 
 /* Returns true if the current thread holds LOCK, false
 }
 
 /* Returns true if the current thread holds LOCK, false