Merge branch 'tty-fixes'

* 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

3 files changed, 33 insertions, 17 deletions

diff --git a/drivers/char/tty_buffer.c b/drivers/char/tty_buffer.c
index 3108991c5c8b..66fa4e10d76b 100644
--- a/drivers/char/tty_buffer.c
+++ b/drivers/char/tty_buffer.c
@@ -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);
 }
 
 /**
diff --git a/include/linux/workqueue.h b/include/linux/workqueue.h
index 7ef0c7b94f31..cf24c20de9e4 100644
--- a/include/linux/workqueue.h
+++ b/include/linux/workqueue.h
@@ -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);
diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index addfe2df93b1..ccefe574dcf7 100644
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -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