Return-Path: From: Tim Niemeyer To: Felipe Balbi , Greg KH , stable@vger.kernel.org Cc: Linux Kernel Mailing List , Marcel Holtmann , Gustavo Padovan , Johan Hedberg , jslaby@suse.cz, grant.likely@linaro.org, linux-bluetooth@vger.kernel.org, andreas@biessmann.de Subject: [PATCH] bluetooth: hci_ldisc: fix deadlock condition Date: Fri, 22 Aug 2014 15:45:07 +0200 Message-Id: <1408715107-21299-1-git-send-email-tim.niemeyer@corscience.de> In-Reply-To: <1398265117-11793-2-git-send-email-balbi@ti.com> References: <1398265117-11793-2-git-send-email-balbi@ti.com> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 List-ID: This Patch was applied to 3.10 and 3.2. It's probably missed on 3.4. --------------------- From: Felipe Balbi LDISCs shouldn't call tty->ops->write() from within ->write_wakeup(). ->write_wakeup() is called with port lock taken and IRQs disabled, tty->ops->write() will try to acquire the same port lock and we will deadlock. Acked-by: Marcel Holtmann Reviewed-by: Peter Hurley Reported-by: Huang Shijie Signed-off-by: Felipe Balbi Tested-by: Andreas Bie=C3=9Fmann [tim.niemeyer@corscience.de: rebased on 3.4.103] Signed-off-by: Tim Niemeyer --- drivers/bluetooth/hci_ldisc.c | 25 ++++++++++++++++++++----- drivers/bluetooth/hci_uart.h | 2 ++ 2 files changed, 22 insertions(+), 5 deletions(-) diff --git a/drivers/bluetooth/hci_ldisc.c b/drivers/bluetooth/hci_ldisc.= c index 98a8c05..d4550f9 100644 --- a/drivers/bluetooth/hci_ldisc.c +++ b/drivers/bluetooth/hci_ldisc.c @@ -118,10 +118,6 @@ static inline struct sk_buff *hci_uart_dequeue(struc= t hci_uart *hu) =20 int hci_uart_tx_wakeup(struct hci_uart *hu) { - struct tty_struct *tty =3D hu->tty; - struct hci_dev *hdev =3D hu->hdev; - struct sk_buff *skb; - if (test_and_set_bit(HCI_UART_SENDING, &hu->tx_state)) { set_bit(HCI_UART_TX_WAKEUP, &hu->tx_state); return 0; @@ -129,6 +125,22 @@ int hci_uart_tx_wakeup(struct hci_uart *hu) =20 BT_DBG(""); =20 + schedule_work(&hu->write_work); + + return 0; +} + +static void hci_uart_write_work(struct work_struct *work) +{ + struct hci_uart *hu =3D container_of(work, struct hci_uart, write_work)= ; + struct tty_struct *tty =3D hu->tty; + struct hci_dev *hdev =3D hu->hdev; + struct sk_buff *skb; + + /* REVISIT: should we cope with bad skbs or ->write() returning + * and error value ? + */ + restart: clear_bit(HCI_UART_TX_WAKEUP, &hu->tx_state); =20 @@ -153,7 +165,6 @@ restart: goto restart; =20 clear_bit(HCI_UART_SENDING, &hu->tx_state); - return 0; } =20 /* ------- Interface to HCI layer ------ */ @@ -264,6 +275,8 @@ static int hci_uart_tty_open(struct tty_struct *tty) hu->tty =3D tty; tty->receive_room =3D 65536; =20 + INIT_WORK(&hu->write_work, hci_uart_write_work); + spin_lock_init(&hu->rx_lock); =20 /* Flush any pending characters in the driver and line discipline. */ @@ -298,6 +311,8 @@ static void hci_uart_tty_close(struct tty_struct *tty= ) if (hdev) hci_uart_close(hdev); =20 + cancel_work_sync(&hu->write_work); + if (test_and_clear_bit(HCI_UART_PROTO_SET, &hu->flags)) { if (hdev) { hci_unregister_dev(hdev); diff --git a/drivers/bluetooth/hci_uart.h b/drivers/bluetooth/hci_uart.h index 6cf6ab22..af93d83 100644 --- a/drivers/bluetooth/hci_uart.h +++ b/drivers/bluetooth/hci_uart.h @@ -66,6 +66,8 @@ struct hci_uart { unsigned long flags; unsigned long hdev_flags; =20 + struct work_struct write_work; + struct hci_uart_proto *proto; void *priv; =20 --=20 1.7.10.4