HID: magicmouse: fix race between input_register() and probe()

Since kernel 3.7, it appears that the input registration occured before
the end of magicmouse_setup_input(). This is shown by receiving a lot of
"EV_SYN SYN_REPORT 1" instead of normal "EV_SYN SYN_REPORT 0".
This value means that the output buffer is full, and the user space
is loosing events.

Using .input_configured guarantees that the race is not occuring, and that
the call of "input_set_events_per_packet(input, 60)" is taken into account
by input_register().

Fixes:
https://bugzilla.redhat.com/show_bug.cgi?id=908604

Cc: stable@vger.kernel.org
Reported-and-Tested-By: Clarke Wixon <cwixon@usa.net>
Signed-off-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

1 files changed, 20 insertions, 9 deletions

diff --git a/drivers/hid/hid-magicmouse.c b/drivers/hid/hid-magicmouse.c
index f7f113ba083e..a8ce44296cfd 100644
--- a/drivers/hid/hid-magicmouse.c
+++ b/drivers/hid/hid-magicmouse.c
@@ -462,6 +462,21 @@ static int magicmouse_input_mapping(struct hid_device *hdev,
         return 0;
 }
 
+static void magicmouse_input_configured(struct hid_device *hdev,
+                struct hid_input *hi)
+
+{
+        struct magicmouse_sc *msc = hid_get_drvdata(hdev);
+
+        int ret = magicmouse_setup_input(msc->input, hdev);
+        if (ret) {
+                hid_err(hdev, "magicmouse setup input failed (%d)\n", ret);
+                /* clean msc->input to notify probe() of the failure */
+                msc->input = NULL;
+        }
+}
+
+
 static int magicmouse_probe(struct hid_device *hdev,
         const struct hid_device_id *id)
 {
@@ -493,15 +508,10 @@ static int magicmouse_probe(struct hid_device *hdev,
                 goto err_free;
         }
 
-        /* We do this after hid-input is done parsing reports so that
-         * hid-input uses the most natural button and axis IDs.
-         */
-        if (msc->input) {
-                ret = magicmouse_setup_input(msc->input, hdev);
-                if (ret) {
-                        hid_err(hdev, "magicmouse setup input failed (%d)\n", ret);
-                        goto err_stop_hw;
-                }
+        if (!msc->input) {
+                hid_err(hdev, "magicmouse input not registered\n");
+                ret = -ENOMEM;
+                goto err_stop_hw;
         }
 
         if (id->product == USB_DEVICE_ID_APPLE_MAGICMOUSE)
@@ -568,6 +578,7 @@ static struct hid_driver magicmouse_driver = {
         .remove = magicmouse_remove,
         .raw_event = magicmouse_raw_event,
         .input_mapping = magicmouse_input_mapping,
+        .input_configured = magicmouse_input_configured,
 };
 module_hid_driver(magicmouse_driver);