From: Simon Arlott Fix several instances of dvb-core functions using mutex_lock_interruptible and returning -ERESTARTSYS where the calling function will either never retry or never check the return value. These cause a race condition with dvb_dmxdev_filter_free and dvb_dvr_release, both of which are filesystem release functions whose return value is ignored and will never be retried. When this happens it becomes impossible to open dvr0 again (-EBUSY) since it has not been released properly. Signed-off-by: Simon Arlott Cc: Andreas Oberritter Cc: Mauro Carvalho Chehab a Signed-off-by: Andrew Morton --- drivers/media/dvb/dvb-core/dmxdev.c | 12 +++--------- drivers/media/dvb/dvb-core/dvb_demux.c | 21 +++++++-------------- drivers/media/dvb/dvb-core/dvbdev.c | 9 +++------ 3 files changed, 13 insertions(+), 29 deletions(-) diff -puN drivers/media/dvb/dvb-core/dmxdev.c~dvb-core-fix-several-locking-related-problems drivers/media/dvb/dvb-core/dmxdev.c --- a/drivers/media/dvb/dvb-core/dmxdev.c~dvb-core-fix-several-locking-related-problems +++ a/drivers/media/dvb/dvb-core/dmxdev.c @@ -180,8 +180,7 @@ static int dvb_dvr_release(struct inode struct dvb_device *dvbdev = file->private_data; struct dmxdev *dmxdev = dvbdev->priv; - if (mutex_lock_interruptible(&dmxdev->mutex)) - return -ERESTARTSYS; + mutex_lock(&dmxdev->mutex); if ((file->f_flags & O_ACCMODE) == O_WRONLY) { dmxdev->demux->disconnect_frontend(dmxdev->demux); @@ -673,13 +672,8 @@ static int dvb_demux_open(struct inode * static int dvb_dmxdev_filter_free(struct dmxdev *dmxdev, struct dmxdev_filter *dmxdevfilter) { - if (mutex_lock_interruptible(&dmxdev->mutex)) - return -ERESTARTSYS; - - if (mutex_lock_interruptible(&dmxdevfilter->mutex)) { - mutex_unlock(&dmxdev->mutex); - return -ERESTARTSYS; - } + mutex_lock(&dmxdev->mutex); + mutex_lock(&dmxdevfilter->mutex); dvb_dmxdev_filter_stop(dmxdevfilter); dvb_dmxdev_filter_reset(dmxdevfilter); diff -puN drivers/media/dvb/dvb-core/dvb_demux.c~dvb-core-fix-several-locking-related-problems drivers/media/dvb/dvb-core/dvb_demux.c --- a/drivers/media/dvb/dvb-core/dvb_demux.c~dvb-core-fix-several-locking-related-problems +++ a/drivers/media/dvb/dvb-core/dvb_demux.c @@ -673,8 +673,7 @@ static int dmx_ts_feed_stop_filtering(st struct dvb_demux *demux = feed->demux; int ret; - if (mutex_lock_interruptible(&demux->mutex)) - return -ERESTARTSYS; + mutex_lock(&demux->mutex); if (feed->state < DMX_STATE_GO) { mutex_unlock(&demux->mutex); @@ -748,8 +747,7 @@ static int dvbdmx_release_ts_feed(struct struct dvb_demux *demux = (struct dvb_demux *)dmx; struct dvb_demux_feed *feed = (struct dvb_demux_feed *)ts_feed; - if (mutex_lock_interruptible(&demux->mutex)) - return -ERESTARTSYS; + mutex_lock(&demux->mutex); if (feed->state == DMX_STATE_FREE) { mutex_unlock(&demux->mutex); @@ -916,8 +914,7 @@ static int dmx_section_feed_stop_filteri struct dvb_demux *dvbdmx = dvbdmxfeed->demux; int ret; - if (mutex_lock_interruptible(&dvbdmx->mutex)) - return -ERESTARTSYS; + mutex_lock(&dvbdmx->mutex); if (!dvbdmx->stop_feed) { mutex_unlock(&dvbdmx->mutex); @@ -942,8 +939,7 @@ static int dmx_section_feed_release_filt struct dvb_demux_feed *dvbdmxfeed = (struct dvb_demux_feed *)feed; struct dvb_demux *dvbdmx = dvbdmxfeed->demux; - if (mutex_lock_interruptible(&dvbdmx->mutex)) - return -ERESTARTSYS; + mutex_lock(&dvbdmx->mutex); if (dvbdmxfilter->feed != dvbdmxfeed) { mutex_unlock(&dvbdmx->mutex); @@ -1016,8 +1012,7 @@ static int dvbdmx_release_section_feed(s struct dvb_demux_feed *dvbdmxfeed = (struct dvb_demux_feed *)feed; struct dvb_demux *dvbdmx = (struct dvb_demux *)demux; - if (mutex_lock_interruptible(&dvbdmx->mutex)) - return -ERESTARTSYS; + mutex_lock(&dvbdmx->mutex); if (dvbdmxfeed->state == DMX_STATE_FREE) { mutex_unlock(&dvbdmx->mutex); @@ -1126,8 +1121,7 @@ static int dvbdmx_connect_frontend(struc if (demux->frontend) return -EINVAL; - if (mutex_lock_interruptible(&dvbdemux->mutex)) - return -ERESTARTSYS; + mutex_lock(&dvbdemux->mutex); demux->frontend = frontend; mutex_unlock(&dvbdemux->mutex); @@ -1138,8 +1132,7 @@ static int dvbdmx_disconnect_frontend(st { struct dvb_demux *dvbdemux = (struct dvb_demux *)demux; - if (mutex_lock_interruptible(&dvbdemux->mutex)) - return -ERESTARTSYS; + mutex_lock(&dvbdemux->mutex); demux->frontend = NULL; mutex_unlock(&dvbdemux->mutex); diff -puN drivers/media/dvb/dvb-core/dvbdev.c~dvb-core-fix-several-locking-related-problems drivers/media/dvb/dvb-core/dvbdev.c --- a/drivers/media/dvb/dvb-core/dvbdev.c~dvb-core-fix-several-locking-related-problems +++ a/drivers/media/dvb/dvb-core/dvbdev.c @@ -203,8 +203,7 @@ int dvb_register_device(struct dvb_adapt int id; - if (mutex_lock_interruptible(&dvbdev_register_lock)) - return -ERESTARTSYS; + mutex_lock(&dvbdev_register_lock); if ((id = dvbdev_get_free_id (adap, type)) < 0){ mutex_unlock(&dvbdev_register_lock); @@ -294,8 +293,7 @@ int dvb_register_adapter(struct dvb_adap { int num; - if (mutex_lock_interruptible(&dvbdev_register_lock)) - return -ERESTARTSYS; + mutex_lock(&dvbdev_register_lock); if ((num = dvbdev_get_free_adapter_num ()) < 0) { mutex_unlock(&dvbdev_register_lock); @@ -323,8 +321,7 @@ EXPORT_SYMBOL(dvb_register_adapter); int dvb_unregister_adapter(struct dvb_adapter *adap) { - if (mutex_lock_interruptible(&dvbdev_register_lock)) - return -ERESTARTSYS; + mutex_lock(&dvbdev_register_lock); list_del (&adap->list_head); mutex_unlock(&dvbdev_register_lock); return 0; _