HID: fix tty<->hid deadlock

hid_compat_load() runs on the default workqueue, it request_module(), it
execs modprobe, it exits, tty flushes default workqueue, it hangs, because
we are still in it.

Signed-off-by: Jiri Slaby <jirislaby@gmail.com>
Tested-by: <Valdis.Kletnieks@vt.edu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

diff --git a/drivers/hid/hid-core.c b/drivers/hid/hid-core.c
index 18b277a..63c8ce5 100644 (file)
--- a/drivers/hid/hid-core.c
+++ b/drivers/hid/hid-core.c
@@ -1657,6 +1657,7 @@ static void hid_compat_load(struct work_struct *ws)
        request_module("hid-dummy");
 }
 static DECLARE_WORK(hid_compat_work, hid_compat_load);
+static struct workqueue_struct *hid_compat_wq;
 #endif
 
 static int __init hid_init(void)
@@ -1674,7 +1675,12 @@ static int __init hid_init(void)
                goto err_bus;
 
 #ifdef CONFIG_HID_COMPAT
-       schedule_work(&hid_compat_work);
+       hid_compat_wq = create_workqueue("hid_compat");
+       if (!hid_compat_wq) {
+               hidraw_exit();
+               goto err;
+       }
+       queue_work(hid_compat_wq, &hid_compat_work);
 #endif
 
        return 0;
@@ -1686,6 +1692,9 @@ err:
 
 static void __exit hid_exit(void)
 {
+#ifdef CONFIG_HID_COMPAT
+       destroy_workqueue(hid_compat_wq);
+#endif
        hidraw_exit();
        bus_unregister(&hid_bus_type);
 }