Merge branch 'tty-fixes'
Linus Torvalds [Wed, 14 Oct 2009 22:34:55 +0000 (15:34 -0700)]
* branch 'tty-fixes':
  tty: use the new 'flush_delayed_work()' helper to do ldisc flush
  workqueue: add 'flush_delayed_work()' to run and wait for delayed work
  Make flush_to_ldisc properly handle parallel calls

drivers/char/tty_buffer.c
include/linux/workqueue.h
kernel/workqueue.c

index 3108991..66fa4e1 100644 (file)
@@ -402,28 +402,26 @@ static void flush_to_ldisc(struct work_struct *work)
                container_of(work, struct tty_struct, buf.work.work);
        unsigned long   flags;
        struct tty_ldisc *disc;
-       struct tty_buffer *tbuf, *head;
-       char *char_buf;
-       unsigned char *flag_buf;
 
        disc = tty_ldisc_ref(tty);
        if (disc == NULL)       /*  !TTY_LDISC */
                return;
 
        spin_lock_irqsave(&tty->buf.lock, flags);
-       /* So we know a flush is running */
-       set_bit(TTY_FLUSHING, &tty->flags);
-       head = tty->buf.head;
-       if (head != NULL) {
-               tty->buf.head = NULL;
-               for (;;) {
-                       int count = head->commit - head->read;
+
+       if (!test_and_set_bit(TTY_FLUSHING, &tty->flags)) {
+               struct tty_buffer *head;
+               while ((head = tty->buf.head) != NULL) {
+                       int count;
+                       char *char_buf;
+                       unsigned char *flag_buf;
+
+                       count = head->commit - head->read;
                        if (!count) {
                                if (head->next == NULL)
                                        break;
-                               tbuf = head;
-                               head = head->next;
-                               tty_buffer_free(tty, tbuf);
+                               tty->buf.head = head->next;
+                               tty_buffer_free(tty, head);
                                continue;
                        }
                        /* Ldisc or user is trying to flush the buffers
@@ -445,9 +443,9 @@ static void flush_to_ldisc(struct work_struct *work)
                                                        flag_buf, count);
                        spin_lock_irqsave(&tty->buf.lock, flags);
                }
-               /* Restore the queue head */
-               tty->buf.head = head;
+               clear_bit(TTY_FLUSHING, &tty->flags);
        }
+
        /* We may have a deferred request to flush the input buffer,
           if so pull the chain under the lock and empty the queue */
        if (test_bit(TTY_FLUSHPENDING, &tty->flags)) {
@@ -455,7 +453,6 @@ static void flush_to_ldisc(struct work_struct *work)
                clear_bit(TTY_FLUSHPENDING, &tty->flags);
                wake_up(&tty->read_wait);
        }
-       clear_bit(TTY_FLUSHING, &tty->flags);
        spin_unlock_irqrestore(&tty->buf.lock, flags);
 
        tty_ldisc_deref(disc);
@@ -471,7 +468,7 @@ static void flush_to_ldisc(struct work_struct *work)
  */
 void tty_flush_to_ldisc(struct tty_struct *tty)
 {
-       flush_to_ldisc(&tty->buf.work.work);
+       flush_delayed_work(&tty->buf.work);
 }
 
 /**
index 7ef0c7b..cf24c20 100644 (file)
@@ -207,6 +207,7 @@ extern int queue_delayed_work_on(int cpu, struct workqueue_struct *wq,
 
 extern void flush_workqueue(struct workqueue_struct *wq);
 extern void flush_scheduled_work(void);
+extern void flush_delayed_work(struct delayed_work *work);
 
 extern int schedule_work(struct work_struct *work);
 extern int schedule_work_on(int cpu, struct work_struct *work);
index addfe2d..ccefe57 100644 (file)
@@ -640,6 +640,24 @@ int schedule_delayed_work(struct delayed_work *dwork,
 EXPORT_SYMBOL(schedule_delayed_work);
 
 /**
+ * flush_delayed_work - block until a dwork_struct's callback has terminated
+ * @dwork: the delayed work which is to be flushed
+ *
+ * Any timeout is cancelled, and any pending work is run immediately.
+ */
+void flush_delayed_work(struct delayed_work *dwork)
+{
+       if (del_timer(&dwork->timer)) {
+               struct cpu_workqueue_struct *cwq;
+               cwq = wq_per_cpu(keventd_wq, get_cpu());
+               __queue_work(cwq, &dwork->work);
+               put_cpu();
+       }
+       flush_work(&dwork->work);
+}
+EXPORT_SYMBOL(flush_delayed_work);
+
+/**
  * schedule_delayed_work_on - queue work in global workqueue on CPU after delay
  * @cpu: cpu to use
  * @dwork: job to be done