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media: cec: add EPOLLPRI in poll() when dev is unregistered 

If the CEC device was unregistered, then add EPOLLPRI to
the poll() mask. Otherwise a select() that only waits for
exceptions will not wake up. A select() that waits for
read and/or write events *will* wake up on an EPOLLERR, but
not (for some reason) if it just waits for exceptions.

Strangly the epoll functionality will wakeup on EPOLLERR if
you just wait for an exception, so in this respect select()
and epoll differ.

In the end it doesn't really matter, what matters is that
polling file handles are woken up on device unregistration.

Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
This commit is contained in:
Hans Verkuil 2020-12-01 13:44:46 +01:00 committed by Mauro Carvalho Chehab
parent 5cb0a64eff
commit 4f20b7beca
1 changed files with 1 additions and 1 deletions
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2
drivers/media/cec/core/cec-api.c
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@ -40,7 +40,7 @@ static __poll_t cec_poll(struct file *filp,
poll_wait(filp, &fh->wait, poll);
if (!cec_is_registered(adap))
return EPOLLERR | EPOLLHUP;
return EPOLLERR | EPOLLHUP | EPOLLPRI;
mutex_lock(&adap->lock);
if (adap->is_configured &&
adap->transmit_queue_sz < CEC_MAX_MSG_TX_QUEUE_SZ)