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 79dcfb78c4832f6d908add061f8977f4c4110e28..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
-   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) 
 {
@@ -192,16 +192,12 @@ lock_init (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));
 
-  old_level = intr_disable ();
   sema_down (&lock->semaphore);
   lock->holder = thread_current ();
-  intr_set_level (old_level);
 }
 
 /* Tries to acquires LOCK and returns true if successful or false
@@ -209,22 +205,18 @@ lock_acquire (struct lock *lock)
    thread.
 
    This function will not sleep, so it may be called within an
-   interupt handler. */
+   interrupt handler. */
 bool
 lock_try_acquire (struct lock *lock)
 {
-  enum intr_level old_level;
   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 ();
-  intr_set_level (old_level);
-
   return success;
 }
 
@@ -236,15 +228,11 @@ lock_try_acquire (struct lock *lock)
 void
 lock_release (struct lock *lock) 
 {
-  enum intr_level old_level;
-
   ASSERT (lock != NULL);
   ASSERT (lock_held_by_current_thread (lock));
 
-  old_level = intr_disable ();
   lock->holder = NULL;
   sema_up (&lock->semaphore);
-  intr_set_level (old_level);
 }
 
 /* Returns true if the current thread holds LOCK, false