[PATCH 4.18 293/350] media: cec: add new tx/rx status bits to detect aborts/timeouts

Greg Kroah-Hartman
2018-11-11T23:18:08Z

From: Hans Verkuil <hans.verkuil@cisco.com>

commit 7ec2b3b941a666a942859684281b5f6460a0c234 upstream.

If the HDMI cable is disconnected or the CEC adapter is manually
unconfigured, then all pending transmits and wait-for-replies are
aborted. Signal this with new status bits (CEC_RX/TX_STATUS_ABORTED).

If due to (usually) a driver bug a transmit never ends (i.e. the
transmit_done was never called by the driver), then when this times
out the message is marked with CEC_TX_STATUS_TIMEOUT.

This should not happen and is an indication of a driver bug.

Without a separate status bit for this it was impossible to detect
this from userspace.

The 'transmit timed out' kernel message is now a warning, so this
should be more prominent in the kernel log as well.

Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Cc: <stable@vger.kernel.org> # for v4.18 and up
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
Documentation/media/uapi/cec/cec-ioc-receive.rst | 25 +++++++-
drivers/media/cec/cec-adap.c | 68 ++++++-----------------
include/uapi/linux/cec.h | 3 +
3 files changed, 45 insertions(+), 51 deletions(-)

--- a/Documentation/media/uapi/cec/cec-ioc-receive.rst
+++ b/Documentation/media/uapi/cec/cec-ioc-receive.rst
@@ -16,10 +16,10 @@ CEC_RECEIVE, CEC_TRANSMIT - Receive or t
Synopsis
========

-.. c:function:: int ioctl( int fd, CEC_RECEIVE, struct cec_msg *argp )
+.. c:function:: int ioctl( int fd, CEC_RECEIVE, struct cec_msg \*argp )
:name: CEC_RECEIVE

-.. c:function:: int ioctl( int fd, CEC_TRANSMIT, struct cec_msg *argp )
+.. c:function:: int ioctl( int fd, CEC_TRANSMIT, struct cec_msg \*argp )
:name: CEC_TRANSMIT

Arguments
@@ -272,6 +272,19 @@ View On' messages from initiator 0xf ('U
- The transmit failed after one or more retries. This status bit is
mutually exclusive with :ref:`CEC_TX_STATUS_OK <CEC-TX-STATUS-OK>`.
Other bits can still be set to explain which failures were seen.
+ * .. _`CEC-TX-STATUS-ABORTED`:
+
+ - ``CEC_TX_STATUS_ABORTED``
+ - 0x40
+ - The transmit was aborted due to an HDMI disconnect, or the adapter
+ was unconfigured, or a transmit was interrupted, or the driver
+ returned an error when attempting to start a transmit.
+ * .. _`CEC-TX-STATUS-TIMEOUT`:
+
+ - ``CEC_TX_STATUS_TIMEOUT``
+ - 0x80
+ - The transmit timed out. This should not normally happen and this
+ indicates a driver problem.

.. tabularcolumns:: |p{5.6cm}|p{0.9cm}|p{11.0cm}|
@@ -300,6 +313,14 @@ View On' messages from initiator 0xf ('U
- The message was received successfully but the reply was
``CEC_MSG_FEATURE_ABORT``. This status is only set if this message
was the reply to an earlier transmitted message.
+ * .. _`CEC-RX-STATUS-ABORTED`:
+
+ - ``CEC_RX_STATUS_ABORTED``
+ - 0x08
+ - The wait for a reply to an earlier transmitted message was aborted
+ because the HDMI cable was disconnected, the adapter was unconfigured
+ or the :ref:`CEC_TRANSMIT <CEC_RECEIVE>` that waited for a
+ reply was interrupted.

--- a/drivers/media/cec/cec-adap.c
+++ b/drivers/media/cec/cec-adap.c
@@ -325,7 +325,7 @@ static void cec_data_completed(struct ce
*
* This function is called with adap->lock held.
*/
-static void cec_data_cancel(struct cec_data *data)
+static void cec_data_cancel(struct cec_data *data, u8 tx_status)
{
/*
* It's either the current transmit, or it is a pending
@@ -340,13 +340,11 @@ static void cec_data_cancel(struct cec_d
}

if (data->msg.tx_status & CEC_TX_STATUS_OK) {
- /* Mark the canceled RX as a timeout */
data->msg.rx_ts = ktime_get_ns();
- data->msg.rx_status = CEC_RX_STATUS_TIMEOUT;
+ data->msg.rx_status = CEC_RX_STATUS_ABORTED;
} else {
- /* Mark the canceled TX as an error */
data->msg.tx_ts = ktime_get_ns();
- data->msg.tx_status |= CEC_TX_STATUS_ERROR |
+ data->msg.tx_status |= tx_status |
CEC_TX_STATUS_MAX_RETRIES;
data->msg.tx_error_cnt++;
data->attempts = 0;
@@ -374,15 +372,15 @@ static void cec_flush(struct cec_adapter
while (!list_empty(&adap->transmit_queue)) {
data = list_first_entry(&adap->transmit_queue,
struct cec_data, list);
- cec_data_cancel(data);
+ cec_data_cancel(data, CEC_TX_STATUS_ABORTED);
}
if (adap->transmitting)
- cec_data_cancel(adap->transmitting);
+ cec_data_cancel(adap->transmitting, CEC_TX_STATUS_ABORTED);

/* Cancel the pending timeout work. */
list_for_each_entry_safe(data, n, &adap->wait_queue, list) {
if (cancel_delayed_work(&data->work))
- cec_data_cancel(data);
+ cec_data_cancel(data, CEC_TX_STATUS_OK);
/*
* If cancel_delayed_work returned false, then
* the cec_wait_timeout function is running,
@@ -458,12 +456,13 @@ int cec_thread_func(void *_adap)
* so much traffic on the bus that the adapter was
* unable to transmit for CEC_XFER_TIMEOUT_MS (2.1s).
*/
- dprintk(1, "%s: message %*ph timed out\n", __func__,
+ pr_warn("cec-%s: message %*ph timed out\n", adap->name,
adap->transmitting->msg.len,
adap->transmitting->msg.msg);
adap->tx_timeouts++;
/* Just give up on this. */
- cec_data_cancel(adap->transmitting);
+ cec_data_cancel(adap->transmitting,
+ CEC_TX_STATUS_TIMEOUT);
goto unlock;
}

@@ -514,7 +513,7 @@ int cec_thread_func(void *_adap)
/* Tell the adapter to transmit, cancel on error */
if (adap->ops->adap_transmit(adap, data->attempts,
signal_free_time, &data->msg))
- cec_data_cancel(data);
+ cec_data_cancel(data, CEC_TX_STATUS_ABORTED);

unlock:
mutex_unlock(&adap->lock);
@@ -686,8 +685,6 @@ int cec_transmit_msg_fh(struct cec_adapt
{
struct cec_data *data;
u8 last_initiator = 0xff;
- unsigned int timeout;
- int res = 0;

msg->rx_ts = 0;
msg->tx_ts = 0;
@@ -830,47 +827,20 @@ int cec_transmit_msg_fh(struct cec_adapt
return 0;

/*
- * If we don't get a completion before this time something is really
- * wrong and we time out.
- */
- timeout = CEC_XFER_TIMEOUT_MS;
- /* Add the requested timeout if we have to wait for a reply as well */
- if (msg->timeout)
- timeout += msg->timeout;
-
- /*
* Release the lock and wait, retake the lock afterwards.
*/
mutex_unlock(&adap->lock);
- res = wait_for_completion_killable_timeout(&data->c,
- msecs_to_jiffies(timeout));
+ wait_for_completion_killable(&data->c);
mutex_lock(&adap->lock);

- if (data->completed) {
- /* The transmit completed (possibly with an error) */
- *msg = data->msg;
- kfree(data);
- return 0;
- }
- /*
- * The wait for completion timed out or was interrupted, so mark this
- * as non-blocking and disconnect from the filehandle since it is
- * still 'in flight'. When it finally completes it will just drop the
- * result silently.
- */
- data->blocking = false;
- if (data->fh)
- list_del(&data->xfer_list);
- data->fh = NULL;
-
- if (res == 0) { /* timed out */
- /* Check if the reply or the transmit failed */
- if (msg->timeout && (msg->tx_status & CEC_TX_STATUS_OK))
- msg->rx_status = CEC_RX_STATUS_TIMEOUT;
- else
- msg->tx_status = CEC_TX_STATUS_MAX_RETRIES;
- }
- return res > 0 ? 0 : res;
+ /* Cancel the transmit if it was interrupted */
+ if (!data->completed)
+ cec_data_cancel(data, CEC_TX_STATUS_ABORTED);
+
+ /* The transmit completed (possibly with an error) */
+ *msg = data->msg;
+ kfree(data);
+ return 0;
}

/* Helper function to be used by drivers and this framework. */
--- a/include/uapi/linux/cec.h
+++ b/include/uapi/linux/cec.h
@@ -152,10 +152,13 @@ static inline void cec_msg_set_reply_to(
#define CEC_TX_STATUS_LOW_DRIVE (1 << 3)
#define CEC_TX_STATUS_ERROR (1 << 4)
#define CEC_TX_STATUS_MAX_RETRIES (1 << 5)
+#define CEC_TX_STATUS_ABORTED (1 << 6)
+#define CEC_TX_STATUS_TIMEOUT (1 << 7)

#define CEC_RX_STATUS_OK (1 << 0)
#define CEC_RX_STATUS_TIMEOUT (1 << 1)
#define CEC_RX_STATUS_FEATURE_ABORT (1 << 2)
+#define CEC_RX_STATUS_ABORTED (1 << 3)

static inline int cec_msg_status_is_ok(const struct cec_msg *msg)
{