The patch below does not apply to the 5.5-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
From d51224b73d18d207912f15ad4eb7a4b456682729 Mon Sep 17 00:00:00 2001
From: Hans Verkuil hverkuil-cisco@xs4all.nl Date: Wed, 11 Dec 2019 12:47:57 +0100 Subject: [PATCH] media: cec: check 'transmit_in_progress', not 'transmitting'
Currently wait_event_interruptible_timeout is called in cec_thread_func() when adap->transmitting is set. But if the adapter is unconfigured while transmitting, then adap->transmitting is set to NULL. But the hardware is still actually transmitting the message, and that's indicated by adap->transmit_in_progress and we should wait until that is finished or times out before transmitting new messages.
As the original commit says: adap->transmitting is the userspace view, adap->transmit_in_progress reflects the hardware state.
However, if adap->transmitting is NULL and adap->transmit_in_progress is true, then wait_event_interruptible is called (no timeout), which can get stuck indefinitely if the CEC driver is flaky and never marks the transmit-in-progress as 'done'.
So test against transmit_in_progress when deciding whether to use the timeout variant or not, instead of testing against adap->transmitting.
Signed-off-by: Hans Verkuil hverkuil-cisco@xs4all.nl Fixes: 32804fcb612b ("media: cec: keep track of outstanding transmits") Cc: stable@vger.kernel.org # for v4.19 and up Signed-off-by: Mauro Carvalho Chehab mchehab+huawei@kernel.org
diff --git a/drivers/media/cec/cec-adap.c b/drivers/media/cec/cec-adap.c index 1060e633b623..6c95dc471d4c 100644 --- a/drivers/media/cec/cec-adap.c +++ b/drivers/media/cec/cec-adap.c @@ -465,7 +465,7 @@ int cec_thread_func(void *_adap) bool timeout = false; u8 attempts;
- if (adap->transmitting) { + if (adap->transmit_in_progress) { int err;
/* @@ -500,7 +500,7 @@ int cec_thread_func(void *_adap) goto unlock; }
- if (adap->transmitting && timeout) { + if (adap->transmit_in_progress && timeout) { /* * If we timeout, then log that. Normally this does * not happen and it is an indication of a faulty CEC @@ -509,14 +509,18 @@ 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). */ - pr_warn("cec-%s: message %*ph timed out\n", adap->name, - adap->transmitting->msg.len, - adap->transmitting->msg.msg); + if (adap->transmitting) { + pr_warn("cec-%s: message %*ph timed out\n", adap->name, + adap->transmitting->msg.len, + adap->transmitting->msg.msg); + /* Just give up on this. */ + cec_data_cancel(adap->transmitting, + CEC_TX_STATUS_TIMEOUT); + } else { + pr_warn("cec-%s: transmit timed out\n", adap->name); + } adap->transmit_in_progress = false; adap->tx_timeouts++; - /* Just give up on this. */ - cec_data_cancel(adap->transmitting, - CEC_TX_STATUS_TIMEOUT); goto unlock; }