Johannes Stezenbach schrieb: >>>>In dvb_dmxdev_filter_start if we go out because of an error, release >>>>previously allocated demux_feed. >>> >>>This is a bit subtle. The feed is released in dvb_demux_release() (when >>>the device is closed). What was the problem you were trying to fix with >>>this patch? >> >>The problem is if you change the pid filter without closing the demux >>device. For example when changing the channel. Consider the following >>sequence: >>tune(); >>ioctl(DMX_SET_PES_FILTER); >>ioctl(DMX_START); >>... >>ioctl(DMX_STOP); >>tune(); >>ioctl(DMX_SET_PES_FILTER); >>ioctl(DMX_START); >>... >>(xine does it this way for example) >> >>As the status of the filter isn't set to DMXDEV_STATE_GO if an error >>occurs in dvb_dmx_filter_start, it wont be released in >>dvb_dmx_filter_stop. Because the number of filters is limited, it will >>run out of filters after zapping through a few channels > > > Hm, it looks like you are right. The code is just too confusing :-( > > E.g dmx_ts_feed_set() calls dvb_demux_feed_add(), but since theres > no such thing as dmx_ts_feed_unset(), the corresponding call > to dvb_demux_feed_del() is part of dvbdmx_release_ts_feed(). > > What drivers dod you test this with? I came across this problem when I played around with the ttusb_dec driver. When doing some cleanups I changed the return values in the driver->start_feed() callback(ttusb_dec_start_ts_feed) to -EOPNOTSUPP for DMX_PES_TELETEXT/DMX_PES_OTHER filter as the driver can't handle those. Thats the reason why ->start_filtering() failed in my case, but it could also fail in other cases, see below. > > >>Btw just ~5 lines above the one i changed with the patch, there is >>exactly the same situation. And there it is done the way as the patch >>does it. > > > Two questions: > - why does ->start_filtering() fail? If I see this correctly ->start_filtering() calls dmx_ts_feed_start_filtering() which fails if: - it don't get the demux mutex, - feed->state != READY - feed->type != TS_FEED - the driver callback ->start_feed() fails > - does the same bug exist for the section filters? I dont know for sure. I haven't really looked at the section filter code at all. From a first quick glance I would say probably yes( after ->start-filtering() it checks for error but didnt release the filter), but honestly after looking at the code for a couple minutes i find it quite confusing to understand whats really going on ;) I will probably take a closer look when I find some time. Peter > > Johannes > > _______________________________________________ > > linux-dvb@xxxxxxxxxxx > http://www.linuxtv.org/cgi-bin/mailman/listinfo/linux-dvb > >
