| Message ID | 1398265117-11793-2-git-send-email-balbi@ti.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
Dear Felipe Balbi, On Wed, Apr 23, 2014 at 09:58:26AM -0500, Felipe Balbi wrote: > 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 <marcel@holtmann.org> > Reviewed-by: Peter Hurley <peter@hurleysoftware.com> > Reported-by: Huang Shijie <b32955@freescale.com> > Signed-off-by: Felipe Balbi <balbi@ti.com> Tested-by: Andreas Bießmann <andreas@biessmann.de> on custom TI AM37xx board with 3.4.87. Therefore I vote for adding this to stable branches (at least 3.4). It applies with a slight line shifting (init_work is not available there). I wonder if you have seen my approach [1] to fix this deadlock. This stuff is quiet new to me. As I understood the work_queue has a bit more overhead than a tasklet. Therefore I implemented my fix with a tasklet. Would be great if one could shed some light on that. Best regards Andreas Bießmann [1] https://lkml.org/lkml/2014/4/16/425 > --- > drivers/bluetooth/hci_ldisc.c | 24 +++++++++++++++++++----- > drivers/bluetooth/hci_uart.h | 1 + > 2 files changed, 20 insertions(+), 5 deletions(-) -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/drivers/bluetooth/hci_ldisc.c b/drivers/bluetooth/hci_ldisc.c index f1fbf4f..e00f8f5 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(struct hci_uart *hu) int hci_uart_tx_wakeup(struct hci_uart *hu) { - struct tty_struct *tty = hu->tty; - struct hci_dev *hdev = 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) BT_DBG(""); + schedule_work(&hu->write_work); + + return 0; +} + +static void hci_uart_write_work(struct work_struct *work) +{ + struct hci_uart *hu = container_of(work, struct hci_uart, write_work); + struct tty_struct *tty = hu->tty; + struct hci_dev *hdev = 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); @@ -153,7 +165,6 @@ restart: goto restart; clear_bit(HCI_UART_SENDING, &hu->tx_state); - return 0; } static void hci_uart_init_work(struct work_struct *work) @@ -282,6 +293,7 @@ static int hci_uart_tty_open(struct tty_struct *tty) tty->receive_room = 65536; INIT_WORK(&hu->init_ready, hci_uart_init_work); + INIT_WORK(&hu->write_work, hci_uart_write_work); spin_lock_init(&hu->rx_lock); @@ -319,6 +331,8 @@ static void hci_uart_tty_close(struct tty_struct *tty) if (hdev) hci_uart_close(hdev); + cancel_work_sync(&hu->write_work); + if (test_and_clear_bit(HCI_UART_PROTO_SET, &hu->flags)) { if (hdev) { if (test_bit(HCI_UART_REGISTERED, &hu->flags)) diff --git a/drivers/bluetooth/hci_uart.h b/drivers/bluetooth/hci_uart.h index fffa61f..12df101 100644 --- a/drivers/bluetooth/hci_uart.h +++ b/drivers/bluetooth/hci_uart.h @@ -68,6 +68,7 @@ struct hci_uart { unsigned long hdev_flags; struct work_struct init_ready; + struct work_struct write_work; struct hci_uart_proto *proto; void *priv;