From: Dyks, Axel (XL) <xl@xlsigned.net>
Date: Sun, 11 Jun 2006 20:14:35 +0000 (-0300)
Subject: V4L/DVB (4090): Fix cinergyt2_poll() to allow non-blocking IO on frontend
X-Git-Tag: firefly_0821_release~35239^2~79
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=774dd5d9bdcbfe2efb3425e8a0be0b4d01a65c26;p=firefly-linux-kernel-4.4.55.git

V4L/DVB (4090): Fix cinergyt2_poll() to allow non-blocking IO on frontend

cinergyt2_poll()" shouldn't return (POLLIN | POLLRDNORM | POLLPRI) when
there are no pending events. User space programs that do non-bocking IO
using "select()" and/or "poll()" would otherwise produce high system load.
Acked-by: Andreas Oberritter <obi@linuxtv.org>

Signed-off-by: Axel Dyks <xl@xlsigned.net>
Acked-by: Andreas Oberritter <obi@linuxtv.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>
---

diff --git a/drivers/media/dvb/cinergyT2/cinergyT2.c b/drivers/media/dvb/cinergyT2/cinergyT2.c
index c7e4134872d4..8cfdad6f50fb 100644
--- a/drivers/media/dvb/cinergyT2/cinergyT2.c
+++ b/drivers/media/dvb/cinergyT2/cinergyT2.c
@@ -544,15 +544,19 @@ static unsigned int cinergyt2_poll (struct file *file, struct poll_table_struct
 {
 	struct dvb_device *dvbdev = file->private_data;
 	struct cinergyt2 *cinergyt2 = dvbdev->priv;
+       unsigned int mask = 0;
 
 	if (cinergyt2->disconnect_pending || mutex_lock_interruptible(&cinergyt2->sem))
 		return -ERESTARTSYS;
 
 	poll_wait(file, &cinergyt2->poll_wq, wait);
 
+       if (cinergyt2->pending_fe_events != 0)
+	       mask |= (POLLIN | POLLRDNORM | POLLPRI);
+
 	mutex_unlock(&cinergyt2->sem);
 
-	return (POLLIN | POLLRDNORM | POLLPRI);
+       return mask;
 }