| Message ID | 20140320181145.GC3959@saruman.home |
|---|---|
| State | New |
| Headers | show |
On 03/20/2014 02:11 PM, Felipe Balbi wrote: > On Thu, Mar 20, 2014 at 01:31:40PM -0400, Peter Hurley wrote: >> [ +cc Huang Shijie ] >> >> On 03/20/2014 01:16 PM, Felipe Balbi wrote: >>> On Thu, Mar 20, 2014 at 04:42:16PM +0000, Alan Cox wrote: >>>> On Thu, 2014-03-20 at 11:34 -0500, Felipe Balbi wrote: >>>>> Hi, >>>>> >>>>> when 8250 driver calls uart_write_wakeup(), the tty port lock is already >>>>> taken. hci_ldisc.c's implementation of ->write_wakeup() calls >>>>> tty->ops->write() to actually send the characters, but that call will >>>>> try to acquire the same port lock again. >>>>> >>>>> Looking at other line disciplines that looks like a bug in hci_ldisc.c. >>>>> Am I correct to assume that ->write_wakeup() is supposed to *just* >>>>> wakeup the bottom half so we handle ->write() in another context ? >>>>> >>>>> Is it legal to call tty->ops->write() from within ->write_wakeup() ? >>>> >>>> It isn't because you might send all the bytes and go >>>> >>>> write >>>> write_wakeup >>>> write >>>> write wakeup >>>> ... >>>> >>>> and recurse >>> >>> cool, so there really is a bug in hci_ldisc. Marcel, any tips on how do >>> you want this to be sorted out ? >> >> hci_uart_tx_wakeup() should perform the I/O as work. >> FWIW, this was reported by Huang Shijie back on Dec 6. >> >> I'd fix it but I have no way to test it. > > here's a build-tested only patch which is waiting for testing from other > colleagues who've got a platform to reproduce the problem: Where's the cancel_work_sync() on teardown? Regards, Peter Hurley > diff --git a/drivers/bluetooth/hci_ldisc.c b/drivers/bluetooth/hci_ldisc.c > index bc68a44..789000d 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 +125,18 @@ 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, init_ready); > + struct tty_struct *tty = hu->tty; > + struct hci_dev *hdev = hu->hdev; > + struct sk_buff *skb; > + > restart: > clear_bit(HCI_UART_TX_WAKEUP, &hu->tx_state); > > @@ -153,7 +161,6 @@ restart: > goto restart; > > clear_bit(HCI_UART_SENDING, &hu->tx_state); > - return 0; > } > > static void hci_uart_init_work(struct work_struct *work) > @@ -289,6 +296,7 @@ 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); > > 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; > -- To unsubscribe from this list: send the line "unsubscribe linux-serial" 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 bc68a44..789000d 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 +125,18 @@ 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, init_ready); + struct tty_struct *tty = hu->tty; + struct hci_dev *hdev = hu->hdev; + struct sk_buff *skb; + restart: clear_bit(HCI_UART_TX_WAKEUP, &hu->tx_state); @@ -153,7 +161,6 @@ restart: goto restart; clear_bit(HCI_UART_SENDING, &hu->tx_state); - return 0; } static void hci_uart_init_work(struct work_struct *work) @@ -289,6 +296,7 @@ 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); 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;