Commit 9c81496a authored Nov 14, 2010 by Marko Ristola Committed by Mauro Carvalho Chehab Dec 29, 2010

[media] Mantis: append tasklet maintenance for DVB stream delivery



After dvb-core has called mantis-fe->stop_feed(dvbdmxfeed)
the last time (count to zero), no data should ever be copied
with dvb_dmx_swfilter() by a tasklet: the target structure
might be in an unusable state. Caller of mantis_fe->stop_feed()
assumes that feeding is stopped after stop_feed() has been
called, ie. dvb_dmx_swfilter() isn't running, and won't be called.

There is a risk that dvb_dmx_swfilter() references freed resources
(memory or spinlocks or ???) causing instabilities. Thus
tasklet_disable(&mantis->tasklet) must be called inside of
mantis-fe->stop_feed(dvbdmxfeed) when necessary.

Signed-off-by: Marko Ristola <marko.ristola@kolumbus.fi>
Signed-off-by: Manu Abraham <manu@linuxtv.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

parent 116d588e

drivers/media/dvb/mantis/mantis_dvb.c

+3 −0

Original line number	Diff line number	Diff line
		@@ -117,6 +117,7 @@ static int mantis_dvb_start_feed(struct dvb_demux_feed *dvbdmxfeed)
		if (mantis->feeds == 1) {
		dprintk(MANTIS_DEBUG, 1, "mantis start feed & dma");
		mantis_dma_start(mantis);
		tasklet_enable(&mantis->tasklet);
		}

		return mantis->feeds;
		@@ -136,6 +137,7 @@ static int mantis_dvb_stop_feed(struct dvb_demux_feed *dvbdmxfeed)
		mantis->feeds--;
		if (mantis->feeds == 0) {
		dprintk(MANTIS_DEBUG, 1, "mantis stop feed and dma");
		tasklet_disable(&mantis->tasklet);
		mantis_dma_stop(mantis);
		}

		@@ -216,6 +218,7 @@ int __devinit mantis_dvb_init(struct mantis_pci *mantis)

		dvb_net_init(&mantis->dvb_adapter, &mantis->dvbnet, &mantis->demux.dmx);
		tasklet_init(&mantis->tasklet, mantis_dma_xfer, (unsigned long) mantis);
		tasklet_disable(&mantis->tasklet);
		if (mantis->hwconfig) {
		result = config->frontend_init(mantis, mantis->fe);
		if (result < 0) {