Improve comment on thread_unblock().

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

diff --git a/src/threads/thread.c b/src/threads/thread.c
index 1dc34adac7770f6bc53b5e5a1fb6b533ec0043f4..92d1aa899efe1d8bf84c6c7056ae7d45215c687b 100644 (file)
--- a/src/threads/thread.c
+++ b/src/threads/thread.c
@@ -52,9 +52,7 @@ static unsigned thread_ticks;   /* # of timer ticks since last yield. */
 
 /* If false (default), use round-robin scheduler.
    If true, use multi-level feedback queue scheduler.
-   Controlled by kernel command-line options "-o mlfqs".
-   Note that the command line is not parsed until well after
-   thread_init() is called. */
+   Controlled by kernel command-line option "-o mlfqs". */
 bool thread_mlfqs;
 
 static void kernel_thread (thread_func *, void *aux);
@@ -80,10 +78,6 @@ static tid_t allocate_tid (void);
    allocator before trying to create any threads with
    thread_create().
 
-   The kernel command line is not parsed until *after* this
-   function returns, so that when this function runs,
-   thread_mlfqs is always false.
-
    It is not safe to call thread_current() until this function
    finishes. */
 void
@@ -102,10 +96,7 @@ thread_init (void)
 }
 
 /* Starts preemptive thread scheduling by enabling interrupts.
-   Also creates the idle thread.
-
-   By the time this function runs, thread_mlfqs has been properly
-   initialized to its final value. */
+   Also creates the idle thread. */
 void
 thread_start (void) 
 {
@@ -225,7 +216,12 @@ thread_block (void)
 
 /* Transitions a blocked thread T to the ready-to-run state.
    This is an error if T is not blocked.  (Use thread_yield() to
-   make the running thread ready.) */
+   make the running thread ready.)
+
+   This function does not preempt the running thread.  This can
+   be important: if the caller had disabled interrupts itself,
+   it may expect that it can atomically unblock a thread and
+   update other data. */
 void
 thread_unblock (struct thread *t) 
 {