+++ /dev/null
-From d73e172816652772114827abaa2dbc053eecbbd7 Mon Sep 17 00:00:00 2001
-From: Lukas Wunner <lukas@wunner.de>
-Date: Fri, 17 Nov 2017 00:54:53 +0100
-Subject: Bluetooth: hci_serdev: Init hci_uart proto_lock to avoid oops
-MIME-Version: 1.0
-Content-Type: text/plain; charset=UTF-8
-Content-Transfer-Encoding: 8bit
-
-From: Lukas Wunner <lukas@wunner.de>
-
-commit d73e172816652772114827abaa2dbc053eecbbd7 upstream.
-
-John Stultz reports a boot time crash with the HiKey board (which uses
-hci_serdev) occurring in hci_uart_tx_wakeup(). That function is
-contained in hci_ldisc.c, but also called from the newer hci_serdev.c.
-It acquires the proto_lock in struct hci_uart and it turns out that we
-forgot to init the lock in the serdev code path, thus causing the crash.
-
-John bisected the crash to commit 67d2f8781b9f ("Bluetooth: hci_ldisc:
-Allow sleeping while proto locks are held"), but the issue was present
-before and the commit merely exposed it. (Perhaps by luck, the crash
-did not occur with rwlocks.)
-
-Init the proto_lock in the serdev code path to avoid the oops.
-
-Stack trace for posterity:
-
-Unable to handle kernel read from unreadable memory at 406f127000
-[000000406f127000] user address but active_mm is swapper
-Internal error: Oops: 96000005 [#1] PREEMPT SMP
-Hardware name: HiKey Development Board (DT)
-Call trace:
- hci_uart_tx_wakeup+0x38/0x148
- hci_uart_send_frame+0x28/0x38
- hci_send_frame+0x64/0xc0
- hci_cmd_work+0x98/0x110
- process_one_work+0x134/0x330
- worker_thread+0x130/0x468
- kthread+0xf8/0x128
- ret_from_fork+0x10/0x18
-
-Link: https://lkml.org/lkml/2017/11/15/908
-Reported-and-tested-by: John Stultz <john.stultz@linaro.org>
-Cc: Ronald Tschalär <ronald@innovation.ch>
-Cc: Rob Herring <rob.herring@linaro.org>
-Cc: Sumit Semwal <sumit.semwal@linaro.org>
-Signed-off-by: Lukas Wunner <lukas@wunner.de>
-Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
-Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-
----
- drivers/bluetooth/hci_serdev.c | 1 +
- 1 file changed, 1 insertion(+)
-
---- a/drivers/bluetooth/hci_serdev.c
-+++ b/drivers/bluetooth/hci_serdev.c
-@@ -304,6 +304,7 @@ int hci_uart_register_device(struct hci_
- hci_set_drvdata(hdev, hu);
-
- INIT_WORK(&hu->write_work, hci_uart_write_work);
-+ percpu_init_rwsem(&hu->proto_lock);
-
- /* Only when vendor specific setup callback is provided, consider
- * the manufacturer information valid. This avoids filling in the