| Message ID | 1395343807-21618-9-git-send-email-balbi@ti.com |
|---|---|
| State | Accepted |
| Commit | da64c27d3c93ee9f89956b9de86c4127eb244494 |
| Headers | show |
Hi Felipe, > 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. > > Reviewed-by: Peter Hurley <peter@hurleysoftware.com> > Reported-by: Huang Shijie <b32955@freescale.com> > Signed-off-by: Felipe Balbi <balbi@ti.com> > --- > drivers/bluetooth/hci_ldisc.c | 24 +++++++++++++++++++----- > drivers/bluetooth/hci_uart.h | 1 + > 2 files changed, 20 insertions(+), 5 deletions(-) I hope these are not causing any conflicts with bluetooth-next / linux-next. If not, then I can let Greg take it through tty-next tree. Acked-by: Marcel Holtmann <marcel@holtmann.org> Regards Marcel -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
On Thu, Mar 20, 2014 at 12:40:40PM -0700, Marcel Holtmann wrote: > Hi Felipe, > > > 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. > > > > Reviewed-by: Peter Hurley <peter@hurleysoftware.com> > > Reported-by: Huang Shijie <b32955@freescale.com> > > Signed-off-by: Felipe Balbi <balbi@ti.com> > > --- > > drivers/bluetooth/hci_ldisc.c | 24 +++++++++++++++++++----- > > drivers/bluetooth/hci_uart.h | 1 + > > 2 files changed, 20 insertions(+), 5 deletions(-) > > I hope these are not causing any conflicts with bluetooth-next / > linux-next. If not, then I can let Greg take it through tty-next tree. > > Acked-by: Marcel Holtmann <marcel@holtmann.org> tty-next is already closed, i'll rebase (if necessary) once -rc1 is out ;-) cheers
[ +to Marcel Holtmann ] On 03/20/2014 03:30 PM, 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. > > Reviewed-by: Peter Hurley <peter@hurleysoftware.com> > Reported-by: Huang Shijie <b32955@freescale.com> > Signed-off-by: Felipe Balbi <balbi@ti.com> I just noticed this patch wasn't addressed to Marcel; seems like this should go through the bluetooth tree (but not through bluetooth-next because it fixes an oops). Marcel, You may want to build on top of this patch split handling; I noticed some of the protocol drivers are calling hci_uart_tx_wakeup() from work functions already (so don't need to schedule another work...) Regards, Peter Hurley > --- > drivers/bluetooth/hci_ldisc.c | 24 +++++++++++++++++++----- > drivers/bluetooth/hci_uart.h | 1 + > 2 files changed, 20 insertions(+), 5 deletions(-) > > diff --git a/drivers/bluetooth/hci_ldisc.c b/drivers/bluetooth/hci_ldisc.c > index 6e06f6f..77af52f 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) > @@ -281,6 +292,7 @@ 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); > > @@ -318,6 +330,8 @@ 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; > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Hi, On Wed, Mar 26, 2014 at 08:47:15PM -0400, Peter Hurley wrote: > [ +to Marcel Holtmann ] > > On 03/20/2014 03:30 PM, 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. > > > >Reviewed-by: Peter Hurley <peter@hurleysoftware.com> > >Reported-by: Huang Shijie <b32955@freescale.com> > >Signed-off-by: Felipe Balbi <balbi@ti.com> > > I just noticed this patch wasn't addressed to Marcel; > seems like this should go through the bluetooth tree (but not > through bluetooth-next because it fixes an oops). read the archives: http://marc.info/?l=linux-bluetooth&m=139534449409583&w=2 > Marcel, > > You may want to build on top of this patch split handling; > I noticed some of the protocol drivers are calling > hci_uart_tx_wakeup() from work functions already (so don't > need to schedule another work...) I don't think that should be part of $subject, though.
On 03/26/2014 10:09 PM, Felipe Balbi wrote: >> I just noticed this patch wasn't addressed to Marcel; >> seems like this should go through the bluetooth tree (but not >> through bluetooth-next because it fixes an oops). > > read the archives: > > http://marc.info/?l=linux-bluetooth&m=139534449409583&w=2 Sorry. I did actually get Marcel's reply but Thunderbird didn't parent the reply properly in my inbox and I forgot about it. >> Marcel, >> >> You may want to build on top of this patch split handling; >> I noticed some of the protocol drivers are calling >> hci_uart_tx_wakeup() from work functions already (so don't >> need to schedule another work...) > > I don't think that should be part of $subject, though. I don't understand what you mean here. Regards, Peter Hurley -- To unsubscribe from this list: send the line "unsubscribe linux-bluetooth" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Hi, On Wed, Mar 26, 2014 at 10:20:15PM -0400, Peter Hurley wrote: > >>You may want to build on top of this patch split handling; > >>I noticed some of the protocol drivers are calling > >>hci_uart_tx_wakeup() from work functions already (so don't > >>need to schedule another work...) > > > >I don't think that should be part of $subject, though. > > I don't understand what you mean here. it seemed, at first, like you suggested to redo this patch modifying the protocol drivers to avoid two workqueues. But now that I read it again you _did_ write "on top of this patch".
On 20/03/14 19:30, 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. > I think the work queue should be placed into hci_uart_tty_wakeup() and not hci_uart_tx_wakeup() as added by this patch. The reason is that the kernel thread hci_uart_send_frame() calls hci_uart_tx_wakeup() and this patch unnecessarily introduces a work queue in the program flow of that kernel thread. In other words, I think this patch has undesirable side-effects such as adding latency and increased processor loading for hci_uart_send_frame(). Regards, Dean > Reviewed-by: Peter Hurley <peter@hurleysoftware.com> > Reported-by: Huang Shijie <b32955@freescale.com> > Signed-off-by: Felipe Balbi <balbi@ti.com> > --- > drivers/bluetooth/hci_ldisc.c | 24 +++++++++++++++++++----- > drivers/bluetooth/hci_uart.h | 1 + > 2 files changed, 20 insertions(+), 5 deletions(-) > > diff --git a/drivers/bluetooth/hci_ldisc.c b/drivers/bluetooth/hci_ldisc.c > index 6e06f6f..77af52f 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) > @@ -281,6 +292,7 @@ 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); > > @@ -318,6 +330,8 @@ 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; -- 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 6e06f6f..77af52f 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) @@ -281,6 +292,7 @@ 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); @@ -318,6 +330,8 @@ 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;