virtio: console: Add a find_port_by_devt() function

To convert to using cdev as a pointer to avoid kref troubles, we have to
use a different method to get to a port from an inode than the current
container_of method.

Add find_port_by_devt() that looks up all portdevs and ports with those
portdevs to find the right port.

Signed-off-by: Amit Shah <amit.shah@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

1 files changed, 36 insertions, 1 deletions

diff --git a/drivers/char/virtio_console.c b/drivers/char/virtio_console.c
index b70fe96c1ccd..0c8f2aa3074a 100644
--- a/drivers/char/virtio_console.c
+++ b/drivers/char/virtio_console.c
@@ -227,6 +227,41 @@ out:
         return port;
 }
 
+static struct port *find_port_by_devt_in_portdev(struct ports_device *portdev,
+                                                 dev_t dev)
+{
+        struct port *port;
+        unsigned long flags;
+
+        spin_lock_irqsave(&portdev->ports_lock, flags);
+        list_for_each_entry(port, &portdev->ports, list)
+                if (port->cdev.dev == dev)
+                        goto out;
+        port = NULL;
+out:
+        spin_unlock_irqrestore(&portdev->ports_lock, flags);
+
+        return port;
+}
+
+static struct port *find_port_by_devt(dev_t dev)
+{
+        struct ports_device *portdev;
+        struct port *port;
+        unsigned long flags;
+
+        spin_lock_irqsave(&pdrvdata_lock, flags);
+        list_for_each_entry(portdev, &pdrvdata.portdevs, list) {
+                port = find_port_by_devt_in_portdev(portdev, dev);
+                if (port)
+                        goto out;
+        }
+        port = NULL;
+out:
+        spin_unlock_irqrestore(&pdrvdata_lock, flags);
+        return port;
+}
+
 static struct port *find_port_by_id(struct ports_device *portdev, u32 id)
 {
         struct port *port;
@@ -719,7 +754,7 @@ static int port_fops_open(struct inode *inode, struct file *filp)
         struct port *port;
         int ret;
 
-        port = container_of(cdev, struct port, cdev);
+        port = find_port_by_devt(cdev->dev);
         filp->private_data = port;
 
         /*