diff mbox series

[2/5] usb: typec: ucsi: Check for notifications after init

Message ID 20240320073927.1641788-3-lk@c--e.de
State New
Headers show
Series Fix various races in UCSI | expand

Commit Message

Christian A. Ehrhardt March 20, 2024, 7:39 a.m. UTC 
The completion notification for the final SET_NOTIFICATION_ENABLE
command during initialization can include a connector change
notification.  However, at the time this completion notification is
processed, the ucsi struct is not ready to handle this notification.
As a result the notification is ignored and the controller
never sends an interrupt again.

Re-check CCI for a pending connector state change after
initialization is complete. Adjust the corresponding debug
message accordingly.

Fixes: 71a1fa0df2a3 ("usb: typec: ucsi: Store the notification mask")
Cc: stable@vger.kernel.org
Signed-off-by: Christian A. Ehrhardt <lk@c--e.de>
---
 drivers/usb/typec/ucsi/ucsi.c | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

Comments

Heikki Krogerus March 22, 2024, 9:54 a.m. UTC | #1 
On Wed, Mar 20, 2024 at 08:39:23AM +0100, Christian A. Ehrhardt wrote:
> The completion notification for the final SET_NOTIFICATION_ENABLE
> command during initialization can include a connector change
> notification.  However, at the time this completion notification is
> processed, the ucsi struct is not ready to handle this notification.
> As a result the notification is ignored and the controller
> never sends an interrupt again.
> 
> Re-check CCI for a pending connector state change after
> initialization is complete. Adjust the corresponding debug
> message accordingly.
> 
> Fixes: 71a1fa0df2a3 ("usb: typec: ucsi: Store the notification mask")
> Cc: stable@vger.kernel.org
> Signed-off-by: Christian A. Ehrhardt <lk@c--e.de>

Reviewed-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>

> ---
>  drivers/usb/typec/ucsi/ucsi.c | 10 +++++++++-
>  1 file changed, 9 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/usb/typec/ucsi/ucsi.c b/drivers/usb/typec/ucsi/ucsi.c
> index 8a6645ffd938..dceeed207569 100644
> --- a/drivers/usb/typec/ucsi/ucsi.c
> +++ b/drivers/usb/typec/ucsi/ucsi.c
> @@ -1237,7 +1237,7 @@ void ucsi_connector_change(struct ucsi *ucsi, u8 num)
>  	struct ucsi_connector *con = &ucsi->connector[num - 1];
>  
>  	if (!(ucsi->ntfy & UCSI_ENABLE_NTFY_CONNECTOR_CHANGE)) {
> -		dev_dbg(ucsi->dev, "Bogus connector change event\n");
> +		dev_dbg(ucsi->dev, "Early connector change event\n");
>  		return;
>  	}
>  
> @@ -1636,6 +1636,7 @@ static int ucsi_init(struct ucsi *ucsi)
>  {
>  	struct ucsi_connector *con, *connector;
>  	u64 command, ntfy;
> +	u32 cci;
>  	int ret;
>  	int i;
>  
> @@ -1688,6 +1689,13 @@ static int ucsi_init(struct ucsi *ucsi)
>  
>  	ucsi->connector = connector;
>  	ucsi->ntfy = ntfy;
> +
> +	ret = ucsi->ops->read(ucsi, UCSI_CCI, &cci, sizeof(cci));
> +	if (ret)
> +		return ret;
> +	if (UCSI_CCI_CONNECTOR(READ_ONCE(cci)))
> +		ucsi_connector_change(ucsi, cci);
> +
>  	return 0;
>  
>  err_unregister:
> -- 
> 2.40.1
Dmitry Baryshkov March 29, 2024, 4:21 p.m. UTC | #2 
On Wed, Mar 20, 2024 at 08:39:23AM +0100, Christian A. Ehrhardt wrote:
> The completion notification for the final SET_NOTIFICATION_ENABLE
> command during initialization can include a connector change
> notification.  However, at the time this completion notification is
> processed, the ucsi struct is not ready to handle this notification.
> As a result the notification is ignored and the controller
> never sends an interrupt again.
> 
> Re-check CCI for a pending connector state change after
> initialization is complete. Adjust the corresponding debug
> message accordingly.
> 
> Fixes: 71a1fa0df2a3 ("usb: typec: ucsi: Store the notification mask")
> Cc: stable@vger.kernel.org
> Signed-off-by: Christian A. Ehrhardt <lk@c--e.de>
> ---
>  drivers/usb/typec/ucsi/ucsi.c | 10 +++++++++-
>  1 file changed, 9 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/usb/typec/ucsi/ucsi.c b/drivers/usb/typec/ucsi/ucsi.c
> index 8a6645ffd938..dceeed207569 100644
> --- a/drivers/usb/typec/ucsi/ucsi.c
> +++ b/drivers/usb/typec/ucsi/ucsi.c
> @@ -1237,7 +1237,7 @@ void ucsi_connector_change(struct ucsi *ucsi, u8 num)
>  	struct ucsi_connector *con = &ucsi->connector[num - 1];
>  
>  	if (!(ucsi->ntfy & UCSI_ENABLE_NTFY_CONNECTOR_CHANGE)) {
> -		dev_dbg(ucsi->dev, "Bogus connector change event\n");
> +		dev_dbg(ucsi->dev, "Early connector change event\n");
>  		return;
>  	}
>  
> @@ -1636,6 +1636,7 @@ static int ucsi_init(struct ucsi *ucsi)
>  {
>  	struct ucsi_connector *con, *connector;
>  	u64 command, ntfy;
> +	u32 cci;
>  	int ret;
>  	int i;
>  
> @@ -1688,6 +1689,13 @@ static int ucsi_init(struct ucsi *ucsi)
>  
>  	ucsi->connector = connector;
>  	ucsi->ntfy = ntfy;
> +
> +	ret = ucsi->ops->read(ucsi, UCSI_CCI, &cci, sizeof(cci));
> +	if (ret)
> +		return ret;
> +	if (UCSI_CCI_CONNECTOR(READ_ONCE(cci)))
> +		ucsi_connector_change(ucsi, cci);
> +

I think this leaves place for the race. With this patchset + "Ack
connector change early" in place Neil triggered the following backtrace
on sm8550 HDK while testing my UCSI-qcom-fixes patchset:
What happens:

[   10.421640] write: 00000000: 05 00 e7 db 00 00 00 00

SET_NOTIFICATION_ENABLE

[   10.432359] read: 00000000: 10 01 00 00 00 00 00 80 00 00 00 00 00 00 00 00
[   10.469553] read: 00000010: 04 58 29 20 00 00 00 00 00 00 00 00 00 03 30 01
[   10.476783] read: 00000020: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
[   10.489552] notify: 00000000: 00 00 00 80

COMMAND_COMPLETE

[   10.494194] read: 00000000: 10 01 00 00 00 00 00 80 00 00 00 00 00 00 00 00
[   10.501370] read: 00000010: 04 58 29 20 00 00 00 00 00 00 00 00 00 03 30 01
[   10.508578] read: 00000020: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
[   10.515757] write: 00000000: 04 00 02 00 00 00 00 00

ACK_CC_CI(command completed)

[   10.521100] read: 00000000: 10 01 00 00 00 00 00 20 00 00 00 00 00 00 00 00
[   10.528363] read: 00000010: 04 58 29 20 00 00 00 00 00 00 00 00 00 03 30 01
[   10.535603] read: 00000020: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
[   10.549549] notify: 00000000: 00 00 00 20

ACK_COMPLETE

[Here ucsi->connector and ucsi->ntfy are being set by ucsi_init()

[   10.566654] read: 00000010: 04 58 29 20 00 00 00 00 00 00 00 00 00 03 30 01
[   10.593553] notify: 00000000: 02 00 00 20

Event with CONNECTION_CHANGE. It also schedules connector_change work,
because ucsi->ntfy is already set

[   10.595796] read: 00000000: 10 01 00 00 02 00 00 20 00 00 00 00 00 00 00 00
[   10.595798] read: 00000010: 04 58 29 20 00 00 00 00 00 00 00 00 00 03 30 01
[   10.595799] read: 00000020: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00

The CCI read coming from ucsi_init()

[   10.595807] ------------[ cut here ]------------
[   10.595808] WARNING: CPU: 6 PID: 101 at kernel/workqueue.c:2384 __queue_work+0x374/0x474

[skipped the register dump]

[   10.595953]  __queue_work+0x374/0x474
[   10.595956]  queue_work_on+0x68/0x84
[   10.595959]  ucsi_connector_change+0x54/0x88 [typec_ucsi]
[   10.595963]  ucsi_init_work+0x834/0x85c [typec_ucsi]
[   10.595968]  process_one_work+0x148/0x29c
[   10.595971]  worker_thread+0x2fc/0x40c
[   10.595974]  kthread+0x110/0x114
[   10.595978]  ret_from_fork+0x10/0x20
[   10.595985] ---[ end trace 0000000000000000 ]---

Warning, because the work is already scheduled.


>  	return 0;
>  
>  err_unregister:
> -- 
> 2.40.1
>
Christian A. Ehrhardt April 1, 2024, 8:11 p.m. UTC | #3 
Hi,

On Fri, Mar 29, 2024 at 06:21:08PM +0200, Dmitry Baryshkov wrote:
> On Wed, Mar 20, 2024 at 08:39:23AM +0100, Christian A. Ehrhardt wrote:
> > The completion notification for the final SET_NOTIFICATION_ENABLE
> > command during initialization can include a connector change
> > notification.  However, at the time this completion notification is
> > processed, the ucsi struct is not ready to handle this notification.
> > As a result the notification is ignored and the controller
> > never sends an interrupt again.
> > 
> > Re-check CCI for a pending connector state change after
> > initialization is complete. Adjust the corresponding debug
> > message accordingly.
> > 
> > Fixes: 71a1fa0df2a3 ("usb: typec: ucsi: Store the notification mask")
> > Cc: stable@vger.kernel.org
> > Signed-off-by: Christian A. Ehrhardt <lk@c--e.de>
> > ---
> >  drivers/usb/typec/ucsi/ucsi.c | 10 +++++++++-
> >  1 file changed, 9 insertions(+), 1 deletion(-)
> > 
> > diff --git a/drivers/usb/typec/ucsi/ucsi.c b/drivers/usb/typec/ucsi/ucsi.c
> > index 8a6645ffd938..dceeed207569 100644
> > --- a/drivers/usb/typec/ucsi/ucsi.c
> > +++ b/drivers/usb/typec/ucsi/ucsi.c
> > @@ -1237,7 +1237,7 @@ void ucsi_connector_change(struct ucsi *ucsi, u8 num)
> >  	struct ucsi_connector *con = &ucsi->connector[num - 1];
> >  
> >  	if (!(ucsi->ntfy & UCSI_ENABLE_NTFY_CONNECTOR_CHANGE)) {
> > -		dev_dbg(ucsi->dev, "Bogus connector change event\n");
> > +		dev_dbg(ucsi->dev, "Early connector change event\n");
> >  		return;
> >  	}
> >  
> > @@ -1636,6 +1636,7 @@ static int ucsi_init(struct ucsi *ucsi)
> >  {
> >  	struct ucsi_connector *con, *connector;
> >  	u64 command, ntfy;
> > +	u32 cci;
> >  	int ret;
> >  	int i;
> >  
> > @@ -1688,6 +1689,13 @@ static int ucsi_init(struct ucsi *ucsi)
> >  
> >  	ucsi->connector = connector;
> >  	ucsi->ntfy = ntfy;
> > +
> > +	ret = ucsi->ops->read(ucsi, UCSI_CCI, &cci, sizeof(cci));
> > +	if (ret)
> > +		return ret;
> > +	if (UCSI_CCI_CONNECTOR(READ_ONCE(cci)))
> > +		ucsi_connector_change(ucsi, cci);
> > +
> 
> I think this leaves place for the race. With this patchset + "Ack
> connector change early" in place Neil triggered the following backtrace
> on sm8550 HDK while testing my UCSI-qcom-fixes patchset:

Sorry, but this seems to be a brown paper bag change.
- The READ_ONCE is bogus and a remnant of a prevoius verion of the
  change.
- Calling ->read should probably be done with the PPM lock held.
- The argument to ucsi_connector_change() must be
  UCSI_CCI_CONNECTOR(cci) instead of the plain cci.
I'll send a fix.

> What happens:
[ ... ]
> 
> [   10.595807] ------------[ cut here ]------------
> [   10.595808] WARNING: CPU: 6 PID: 101 at kernel/workqueue.c:2384 __queue_work+0x374/0x474
> 
> [skipped the register dump]
> 
> [   10.595953]  __queue_work+0x374/0x474
> [   10.595956]  queue_work_on+0x68/0x84
> [   10.595959]  ucsi_connector_change+0x54/0x88 [typec_ucsi]
> [   10.595963]  ucsi_init_work+0x834/0x85c [typec_ucsi]
> [   10.595968]  process_one_work+0x148/0x29c
> [   10.595971]  worker_thread+0x2fc/0x40c
> [   10.595974]  kthread+0x110/0x114
> [   10.595978]  ret_from_fork+0x10/0x20
> [   10.595985] ---[ end trace 0000000000000000 ]---
> 
> Warning, because the work is already scheduled.

No, the reason is the wrong connector number. Scheduling a work that
is already scheduled is fine.

Best regards
Christian
diff mbox series

Patch

diff --git a/drivers/usb/typec/ucsi/ucsi.c b/drivers/usb/typec/ucsi/ucsi.c
index 8a6645ffd938..dceeed207569 100644
--- a/drivers/usb/typec/ucsi/ucsi.c
+++ b/drivers/usb/typec/ucsi/ucsi.c
@@ -1237,7 +1237,7 @@  void ucsi_connector_change(struct ucsi *ucsi, u8 num)
 	struct ucsi_connector *con = &ucsi->connector[num - 1];
 
 	if (!(ucsi->ntfy & UCSI_ENABLE_NTFY_CONNECTOR_CHANGE)) {
-		dev_dbg(ucsi->dev, "Bogus connector change event\n");
+		dev_dbg(ucsi->dev, "Early connector change event\n");
 		return;
 	}
 
@@ -1636,6 +1636,7 @@  static int ucsi_init(struct ucsi *ucsi)
 {
 	struct ucsi_connector *con, *connector;
 	u64 command, ntfy;
+	u32 cci;
 	int ret;
 	int i;
 
@@ -1688,6 +1689,13 @@  static int ucsi_init(struct ucsi *ucsi)
 
 	ucsi->connector = connector;
 	ucsi->ntfy = ntfy;
+
+	ret = ucsi->ops->read(ucsi, UCSI_CCI, &cci, sizeof(cci));
+	if (ret)
+		return ret;
+	if (UCSI_CCI_CONNECTOR(READ_ONCE(cci)))
+		ucsi_connector_change(ucsi, cci);
+
 	return 0;
 
 err_unregister: