From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751671AbXCDRqu (ORCPT ); Sun, 4 Mar 2007 12:46:50 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751535AbXCDRqu (ORCPT ); Sun, 4 Mar 2007 12:46:50 -0500 Received: from proxima.lp0.eu ([85.158.45.36]:35591 "EHLO proxima.lp0.eu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751446AbXCDRqt (ORCPT ); Sun, 4 Mar 2007 12:46:49 -0500 Message-ID: <45EB05D2.90608@simon.arlott.org.uk> Date: Sun, 04 Mar 2007 17:45:54 +0000 From: Simon Arlott User-Agent: Thunderbird 1.5.0.5 (X11/20060819) MIME-Version: 1.0 To: Andrew Morton CC: Mauro , Andreas Oberritter , Linux Kernel Mailing List , linux-dvb@linuxtv.org Subject: [PATCH] dvb-core: Fix several locking related problems. References: <45DCB3A3.3060705@simon.arlott.org.uk> <45E08886.50606@linuxtv.org> <45E08BFD.3080203@simon.arlott.org.uk> <45E9D923.7040707@simon.arlott.org.uk> <45EAE894.1010000@linuxtv.org> In-Reply-To: <45EAE894.1010000@linuxtv.org> X-Enigmail-Version: 0.94.1.2 OpenPGP: id=89C93563 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org 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 --- On 04/03/07 15:41, Andreas Oberritter wrote: > please send an updated patch together with > Signed-off-by line to Mauro and ask him to apply > it for inclusion into the -mm tree for further testing. Unless there are other -mm trees I've not heard about, presumably I should just do this myself. Doesn't linux-dvb have it's own development tree this would get better tested in? The dvb_dvr_release change has been working for me for 6 months and the dvb_dmxdev_filter_free (dvb_dmxdev_filter_free) change looks equivalent. See http://www.linuxtv.org/pipermail/linux-dvb/2007-February/016120.html for an example of the bug before and after fixing. All the other changes run ok for me but should have lockdep enabled when testing (if there's a possible deadlock somewhere, using _interruptible will hide it). 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 --git a/drivers/media/dvb/dvb-core/dmxdev.c b/drivers/media/dvb/dvb-core/dmxdev.c index fc77de4..a5c0e1a 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 fcff5ea..6d8d1c3 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 b4553ae..1e0f01a 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; -- 1.5.0.1 -- Simon Arlott