thread: Do not disable interrupts unnecessarily while initializing stack.

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

diff --git a/src/threads/thread.c b/src/threads/thread.c
index 2532463bdbbf5d8f2544cba0b590ae070d2d07e1..87f22b80607b4faba8ae2b1e9f93dc5d6659d8cc 100644 (file)
--- a/src/threads/thread.c
+++ b/src/threads/thread.c
@@ -68,7 +68,7 @@ static void init_thread (struct thread *, const char *name, int priority);
 static bool is_thread (struct thread *) UNUSED;
 static void *alloc_frame (struct thread *, size_t size);
 static void schedule (void);
-void schedule_tail (struct thread *prev);
+void thread_schedule_tail (struct thread *prev);
 static tid_t allocate_tid (void);
 
 /* Initializes the threading system by transforming the code
@@ -171,7 +171,6 @@ thread_create (const char *name, int priority,
   struct switch_entry_frame *ef;
   struct switch_threads_frame *sf;
   tid_t tid;
-  enum intr_level old_level;
 
   ASSERT (function != NULL);
 
@@ -184,11 +183,6 @@ thread_create (const char *name, int priority,
   init_thread (t, name, priority);
   tid = t->tid = allocate_tid ();
 
-  /* Prepare thread for first run by initializing its stack.
-     Do this atomically so intermediate values for the 'stack' 
-     member cannot be observed. */
-  old_level = intr_disable ();
-
   /* Stack frame for kernel_thread(). */
   kf = alloc_frame (t, sizeof *kf);
   kf->eip = NULL;
@@ -204,8 +198,6 @@ thread_create (const char *name, int priority,
   sf->eip = switch_entry;
   sf->ebp = 0;
 
-  intr_set_level (old_level);
-
   /* Add to run queue. */
   thread_unblock (t);
 
@@ -296,7 +288,7 @@ thread_exit (void)
 
   /* Remove thread from all threads list, set our status to dying,
      and schedule another process.  That process will destroy us
-     when it call schedule_tail(). */
+     when it calls thread_schedule_tail(). */
   intr_disable ();
   list_remove (&thread_current()->allelem);
   thread_current ()->status = THREAD_DYING;
@@ -459,6 +451,8 @@ is_thread (struct thread *t)
 static void
 init_thread (struct thread *t, const char *name, int priority)
 {
+  enum intr_level old_level;
+
   ASSERT (t != NULL);
   ASSERT (PRI_MIN <= priority && priority <= PRI_MAX);
   ASSERT (name != NULL);
@@ -469,7 +463,10 @@ init_thread (struct thread *t, const char *name, int priority)
   t->stack = (uint8_t *) t + PGSIZE;
   t->priority = priority;
   t->magic = THREAD_MAGIC;
+
+  old_level = intr_disable ();
   list_push_back (&all_list, &t->allelem);
+  intr_set_level (old_level);
 }
 
 /* Allocates a SIZE-byte frame at the top of thread T's stack and
@@ -516,7 +513,7 @@ next_thread_to_run (void)
    After this function and its caller returns, the thread switch
    is complete. */
 void
-schedule_tail (struct thread *prev) 
+thread_schedule_tail (struct thread *prev)
 {
   struct thread *cur = running_thread ();
   
@@ -550,8 +547,8 @@ schedule_tail (struct thread *prev)
    running to some other state.  This function finds another
    thread to run and switches to it.
 
-   It's not safe to call printf() until schedule_tail() has
-   completed. */
+   It's not safe to call printf() until thread_schedule_tail()
+   has completed. */
 static void
 schedule (void) 
 {
@@ -565,7 +562,7 @@ schedule (void)
 
   if (cur != next)
     prev = switch_threads (cur, next);
-  schedule_tail (prev); 
+  thread_schedule_tail (prev);
 }
 
 /* Returns a tid to use for a new thread. */