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[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>
This commit is contained in:
Marko Ristola 2010-11-14 14:09:04 -03:00 committed by Mauro Carvalho Chehab
parent 116d588ea2
commit 9c81496a88
1 changed files with 3 additions and 0 deletions
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3
drivers/media/dvb/mantis/mantis_dvb.c
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@ -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) {