[PATCH v5 3/4] v4l: async: do not hold list_lock when re-probing devices

[Niklas Söderlund]

There is no good reason to hold the list_lock when re-probing the
devices and it prevents a clean implementation of subdevice notifiers.
Move the actual release of the devices outside of the loop which
requires the lock to be held.

Signed-off-by: Niklas Söderlund <niklas.soderlund+rene...@ragnatech.se>
---
 drivers/media/v4l2-core/v4l2-async.c | 19 +++++++++----------
 1 file changed, 9 insertions(+), 10 deletions(-)

diff --git a/drivers/media/v4l2-core/v4l2-async.c 
b/drivers/media/v4l2-core/v4l2-async.c
index 67852f0f2d3000c9..d91ff0a33fd3eaff 100644
--- a/drivers/media/v4l2-core/v4l2-async.c
+++ b/drivers/media/v4l2-core/v4l2-async.c
@@ -206,7 +206,7 @@ void v4l2_async_notifier_unregister(struct 
v4l2_async_notifier *notifier)
        unsigned int notif_n_subdev = notifier->num_subdevs;
        unsigned int n_subdev = min(notif_n_subdev, V4L2_MAX_SUBDEVS);
        struct device **dev;
-       int i = 0;
+       int i, count = 0;
 
        if (!notifier->v4l2_dev)
                return;
@@ -223,27 +223,26 @@ void v4l2_async_notifier_unregister(struct 
v4l2_async_notifier *notifier)
        list_del(&notifier->list);
 
        list_for_each_entry_safe(sd, tmp, &notifier->done, async_list) {
-               struct device *d;
-
-               d = get_device(sd->dev);
+               dev[count] = get_device(sd->dev);
+               count++;
 
                if (notifier->unbind)
                        notifier->unbind(notifier, sd, sd->asd);
 
                v4l2_async_cleanup(sd);
-
-               /* If we handled USB devices, we'd have to lock the parent too 
*/
-               device_release_driver(d);
-
-               dev[i++] = d;
        }
 
        mutex_unlock(&list_lock);
 
+       for (i = 0; i < count; i++) {
+               /* If we handled USB devices, we'd have to lock the parent too 
*/
+               device_release_driver(dev[i]);
+       }
+
        /*
         * Call device_attach() to reprobe devices
         */
-       while (i--) {
+       for (i = 0; i < count; i++) {
                struct device *d = dev[i];
 
                if (d && device_attach(d) < 0) {
-- 
2.13.1