-#include "thread.h"
+#include "threads/thread.h"
+#include <debug.h>
#include <stddef.h>
-#include "debug.h"
-#include "interrupt.h"
-#include "intr-stubs.h"
-#include "lib.h"
-#include "mmu.h"
-#include "palloc.h"
-#include "random.h"
-#include "switch.h"
+#include <random.h>
+#include <string.h>
+#include "threads/interrupt.h"
+#include "threads/intr-stubs.h"
+#include "threads/mmu.h"
+#include "threads/palloc.h"
+#include "threads/switch.h"
#ifdef USERPROG
-#include "gdt.h"
+#include "userprog/gdt.h"
#endif
+/* Value for struct thread's `magic' member.
+ Used to detect stack overflow. See the big comment at the top
+ of thread.h for details. */
#define THREAD_MAGIC 0x1234abcdu
/* List of processes in THREAD_READY state, that is, processes
that are ready to run but not actually running. */
-static struct list run_queue;
+static struct list ready_list;
/* Idle thread. */
static struct thread *idle_thread; /* Thread. */
static void idle (void *aux UNUSED); /* Thread function. */
+/* Initial thread.
+ This is the thread running main(). */
+static struct thread *initial_thread;
+
/* Stack frame for kernel_thread(). */
struct kernel_thread_frame
{
void
thread_init (void)
{
- struct thread *t;
-
ASSERT (intr_get_level () == INTR_OFF);
/* Set up a thread structure for the running thread. */
- t = running_thread ();
- init_thread (t, "main");
- t->status = THREAD_RUNNING;
+ initial_thread = running_thread ();
+ init_thread (initial_thread, "main");
+ initial_thread->status = THREAD_RUNNING;
/* Initialize run queue. */
- list_init (&run_queue);
+ list_init (&ready_list);
}
/* Starts preemptive thread scheduling by enabling interrupts.
sf->eip = switch_entry;
/* Add to run queue. */
- thread_wake (t);
+ thread_unblock (t);
return t;
}
sf->eip = switch_entry;
/* Add to run queue. */
- thread_wake (t);
+ thread_unblock (t);
return true;
}
#endif
-/* Transitions T from its current state to THREAD_READY, the
- ready-to-run state. On entry, T must be ready or blocked.
+/* Transitions a blocked thread T from its current state to the
+ ready-to-run state. If T is not blocked, there is no effect.
(Use thread_yield() to make the running thread ready.) */
void
-thread_wake (struct thread *t)
+thread_unblock (struct thread *t)
{
+ enum intr_level old_level;
+
ASSERT (is_thread (t));
- ASSERT (t->status == THREAD_READY || t->status == THREAD_BLOCKED);
- if (t->status != THREAD_READY)
+
+ old_level = intr_disable ();
+ if (t->status == THREAD_BLOCKED)
{
- list_push_back (&run_queue, &t->rq_elem);
+ list_push_back (&ready_list, &t->elem);
t->status = THREAD_READY;
}
+ intr_set_level (old_level);
}
/* Returns the name of thread T. */
}
/* Returns the running thread.
- This is running_thread() plus a couple of sanity checks. */
+ This is running_thread() plus a couple of sanity checks.
+ See the big comment at the top of thread.h for details. */
struct thread *
thread_current (void)
{
{
ASSERT (!intr_context ());
+ /* Just set our status to dying and schedule another process.
+ We will be destroyed during the call to schedule_tail(). */
intr_disable ();
thread_current ()->status = THREAD_DYING;
schedule ();
ASSERT (!intr_context ());
old_level = intr_disable ();
- list_push_back (&run_queue, &cur->rq_elem);
+ list_push_back (&ready_list, &cur->elem);
cur->status = THREAD_READY;
schedule ();
intr_set_level (old_level);
}
/* Puts the current thread to sleep. It will not be scheduled
- again until awoken by thread_wake(). */
+ again until awoken by thread_unblock().
+
+ This function must be called with interrupts turned off. It
+ is usually a better idea to use one of the synchronization
+ primitives in synch.h. */
void
-thread_sleep (void)
+thread_block (void)
{
ASSERT (!intr_context ());
ASSERT (intr_get_level () == INTR_OFF);
/* Let someone else run. */
intr_disable ();
- thread_sleep ();
+ thread_block ();
intr_enable ();
}
}
return t;
}
-/* Initializes T as a new thread named NAME. */
+/* Initializes T as a new, blocked thread named NAME. */
static void
init_thread (struct thread *t, const char *name)
{
static struct thread *
next_thread_to_run (void)
{
- if (list_empty (&run_queue))
+ if (list_empty (&ready_list))
return idle_thread;
else
- return list_entry (list_pop_front (&run_queue), struct thread, rq_elem);
+ return list_entry (list_pop_front (&ready_list), struct thread, elem);
}
/* Destroys T, which must be in the dying state and must not be
#ifdef USERPROG
addrspace_destroy (t);
#endif
- palloc_free (t);
+ if (t != initial_thread)
+ palloc_free (t);
}
/* Completes a thread switch by activating the new thread's page
ASSERT (intr_get_level () == INTR_OFF);
+ /* Mark us as running. */
cur->status = THREAD_RUNNING;
- if (prev != NULL && prev->status == THREAD_DYING)
- destroy_thread (prev);
#ifdef USERPROG
+ /* Activate the new address space. */
addrspace_activate (cur);
#endif
+
+ /* If the thread we switched from is dying, destroy it.
+ This must happen late because it's not a good idea to
+ e.g. destroy the page table you're currently using. */
+ if (prev != NULL && prev->status == THREAD_DYING)
+ destroy_thread (prev);
}
/* Schedules a new process. At entry, interrupts must be off and