1 files changed, 44 insertions, 8 deletions

diff --git a/arch/um/drivers/chan_kern.c b/arch/um/drivers/chan_kern.c
index a4e64edb8f38..749d2bf59599 100644
--- a/arch/um/drivers/chan_kern.c
+++ b/arch/um/drivers/chan_kern.c
@@ -171,19 +171,55 @@ int enable_chan(struct line *line)
 	return err;
 }
 
+/* Items are added in IRQ context, when free_irq can't be called, and
+ * removed in process context, when it can.
+ * This handles interrupt sources which disappear, and which need to
+ * be permanently disabled.  This is discovered in IRQ context, but
+ * the freeing of the IRQ must be done later.
+ */
+static DEFINE_SPINLOCK(irqs_to_free_lock);
+static LIST_HEAD(irqs_to_free);
+
+void free_irqs(void)
+{
+	struct chan *chan;
+	LIST_HEAD(list);
+	struct list_head *ele;
+	unsigned long flags;
+
+	spin_lock_irqsave(&irqs_to_free_lock, flags);
+	list_splice_init(&irqs_to_free, &list);
+	spin_unlock_irqrestore(&irqs_to_free_lock, flags);
+
+	list_for_each(ele, &list) {
+		chan = list_entry(ele, struct chan, free_list);
+
+		if (chan->input && chan->enabled)
+			um_free_irq(chan->line->driver->read_irq, chan);
+		if (chan->output && chan->enabled)
+			um_free_irq(chan->line->driver->write_irq, chan);
+		chan->enabled = 0;
+	}
+}
+
 static void close_one_chan(struct chan *chan, int delay_free_irq)
 {
+	unsigned long flags;
+
 	if (!chan->opened)
 		return;
 
-    /* we can safely call free now - it will be marked
-     *  as free and freed once the IRQ stopped processing
-     */
-	if (chan->input && chan->enabled)
-		um_free_irq(chan->line->driver->read_irq, chan);
-	if (chan->output && chan->enabled)
-		um_free_irq(chan->line->driver->write_irq, chan);
-	chan->enabled = 0;
+	if (delay_free_irq) {
+		spin_lock_irqsave(&irqs_to_free_lock, flags);
+		list_add(&chan->free_list, &irqs_to_free);
+		spin_unlock_irqrestore(&irqs_to_free_lock, flags);
+	} else {
+		if (chan->input && chan->enabled)
+			um_free_irq(chan->line->driver->read_irq, chan);
+		if (chan->output && chan->enabled)
+			um_free_irq(chan->line->driver->write_irq, chan);
+		chan->enabled = 0;
+	}
 	if (chan->ops->close != NULL)
 		(*chan->ops->close)(chan->fd, chan->data);