From: Simon Arlott Date: Sat, 10 Mar 2007 09:21:25 +0000 (-0300) Subject: V4L/DVB (5400): Core: fix several locking related problems X-Git-Url: http://git.cdn.openwrt.org/?a=commitdiff_plain;h=c278850206fd9df0bb62a72ca0b277fe20c5a452;p=openwrt%2Fstaging%2Fblogic.git V4L/DVB (5400): Core: fix several locking related problems 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 Signed-off-by: Andrew Morton Acked-By: Johannes Stezenbach Signed-off-by: Mauro Carvalho Chehab --- diff --git a/drivers/media/dvb/dvb-core/dmxdev.c b/drivers/media/dvb/dvb-core/dmxdev.c index fc77de45ca4d..a5c0e1a3e6d1 100644 --- a/drivers/media/dvb/dvb-core/dmxdev.c +++ b/drivers/media/dvb/dvb-core/dmxdev.c @@ -180,8 +180,7 @@ static int dvb_dvr_release(struct inode *inode, struct file *file) 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 *inode, struct file *file) 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 --git a/drivers/media/dvb/dvb-core/dvb_demux.c b/drivers/media/dvb/dvb-core/dvb_demux.c index fcff5eab21a3..6d8d1c3df863 100644 --- a/drivers/media/dvb/dvb-core/dvb_demux.c +++ b/drivers/media/dvb/dvb-core/dvb_demux.c @@ -673,8 +673,7 @@ static int dmx_ts_feed_stop_filtering(struct dmx_ts_feed *ts_feed) 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 dmx_demux *dmx, 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_filtering(struct dmx_section_feed *feed) 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_filter(struct dmx_section_feed *feed, 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(struct dmx_demux *demux, 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(struct dmx_demux *demux, 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(struct dmx_demux *demux) { 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 --git a/drivers/media/dvb/dvb-core/dvbdev.c b/drivers/media/dvb/dvb-core/dvbdev.c index 490337b5ee3e..14a372a0fe8b 100644 --- a/drivers/media/dvb/dvb-core/dvbdev.c +++ b/drivers/media/dvb/dvb-core/dvbdev.c @@ -203,8 +203,7 @@ int dvb_register_device(struct dvb_adapter *adap, struct dvb_device **pdvbdev, 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_adapter *adap, const char *name, struct modu { 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;