libdvbv5: Retry FE_GET_PROPERTY ioctl if it returns EAGAIN

PATCH New David Howells 1 participant 1 message Apr 14, 2015 Media (V4L/DVB)

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David Howells

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2015-04-14 14:48 UTC #0 lore raw

PATCH 1/1 libdvbv5: Retry FE_GET_PROPERTY ioctl if it returns EAGAIN

Retry the FE_GET_PROPERTY ioctl used to determine if we have a DVBv5 device if it returns EAGAIN indicating the driver is currently locked by the kernel.

Also skip over subsequent information gathering calls to FE_GET_PROPERTY that return EAGAIN.

Original-author: Mauro Carvalho Chehab <[email protected]>

Signed-off-by David Howells <[email protected]>

---
 dvb-fe.c |   10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

lib/libdvbv5/dvb-fe.c +8 -2

index 04ad907..3657334 100644
@@ -171,9 +171,12 @@ struct dvb_v5_fe_parms *dvb_fe_open_flags(int adapter, int frontend,
 	dtv_prop.props = parms->dvb_prop;
 
 	/* Detect a DVBv3 device */
-	if (ioctl(fd, FE_GET_PROPERTY, &dtv_prop) == -1) {
+	while (ioctl(fd, FE_GET_PROPERTY, &dtv_prop) == -1) {
+		if (errno == EAGAIN)
+			continue;
 		parms->dvb_prop[0].u.data = 0x300;
 		parms->dvb_prop[1].u.data = SYS_UNDEFINED;
+		break;
 	}
 	parms->p.version = parms->dvb_prop[0].u.data;
 	parms->p.current_sys = parms->dvb_prop[1].u.data;

@@ -1336,8 +1339,11 @@ int dvb_fe_get_stats(struct dvb_v5_fe_parms *p)
 		props.props = parms->stats.prop;
 
 		/* Do a DVBv5.10 stats call */
-		if (ioctl(parms->fd, FE_GET_PROPERTY, &props) == -1)
+		if (ioctl(parms->fd, FE_GET_PROPERTY, &props) == -1) {
+			if (errno == EAGAIN)
+				return 0;
 			goto dvbv3_fallback;
+		}
 
 		/*
 		 * All props with len=0 mean that this device doesn't have any