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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 <simon@fire.lp0.eu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-By: Johannes Stezenbach <js@linuxtv.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>
This commit is contained in:
Simon Arlott 2007-03-10 06:21:25 -03:00 committed by Mauro Carvalho Chehab
parent b10fece583
commit c278850206
3 changed files with 13 additions and 29 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

12
drivers/media/dvb/dvb-core/dmxdev.c
View File

@ -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);

21
drivers/media/dvb/dvb-core/dvb_demux.c
View File

@ -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);

9
drivers/media/dvb/dvb-core/dvbdev.c
View File

@ -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;