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V4L/DVB: fix dvb frontend lockup

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If my dvb device is removed while in use, I got the following oops:

[ 4920.484084] Call Trace:
[ 4920.484102]  [<c102daad>] ? default_wake_function+0x0/0x8
[ 4920.484147]  [<f8cb09e1>] ? dvb_unregister_frontend+0x95/0xcc [dvb_core]
[ 4920.484157]  [<c1044412>] ? autoremove_wake_function+0x0/0x2d
[ 4920.484168]  [<f8dd1af2>] ? dvb_usb_adapter_frontend_exit+0x12/0x21 [dvb_usb]
[ 4920.484176]  [<f8dd12f1>] ? dvb_usb_exit+0x26/0x88 [dvb_usb]
[ 4920.484184]  [<f8dd138d>] ? dvb_usb_device_exit+0x3a/0x4a [dvb_usb]
[ 4920.484217]  [<f7fe1b08>] ? usb_unbind_interface+0x3f/0xb4 [usbcore]
[ 4920.484227]  [<c11a4178>] ? __device_release_driver+0x74/0xb7
[ 4920.484233]  [<c11a4247>] ? device_release_driver+0x15/0x1e
[ 4920.484243]  [<c11a3a33>] ? bus_remove_device+0x6e/0x87
[ 4920.484249]  [<c11a26d6>] ? device_del+0xfa/0x152
[ 4920.484264]  [<f7fdf609>] ? usb_disable_device+0x59/0xb9 [usbcore]
[ 4920.484279]  [<f7fdb9ee>] ? usb_disconnect+0x70/0xdc [usbcore]
[ 4920.484294]  [<f7fdc728>] ? hub_thread+0x521/0xe1d [usbcore]
[ 4920.484301]  [<c1044412>] ? autoremove_wake_function+0x0/0x2d
[ 4920.484316]  [<f7fdc207>] ? hub_thread+0x0/0xe1d [usbcore]
[ 4920.484321]  [<c10441e0>] ? kthread+0x61/0x66
[ 4920.484327]  [<c104417f>] ? kthread+0x0/0x66
[ 4920.484336]  [<c1003d47>] ? kernel_thread_helper+0x7/0x10

If there are users (for example users == -2) :
 - dvb_unregister_frontend :
 - stop kernel thread with dvb_frontend_stop :
  - fepriv->exit = 1;
  - thread loop catch stop event and break while loop
  - fepriv->thread = NULL; and fepriv->exit = 0;
 - dvb_unregister_frontend wait on "fepriv->dvbdev->wait_queue" that fepriv->dvbdev->users==-1.
The user finish :
 - dvb_frontend_release - set users to -1
 - don't wait wait_queue because fepriv->exit != 1

=> dvb_unregister_frontend never exit the wait queue.

Signed-off-by: Matthieu CASTET <castet.matthieu@free.fr>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
This commit is contained in:
matthieu castet 2010-05-05 15:59:20 -03:00 committed by Mauro Carvalho Chehab
parent 8b661b508b
commit e36309f54a
1 changed files with 17 additions and 8 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

25
drivers/media/dvb/dvb-core/dvb_frontend.c
View File

@ -95,6 +95,10 @@ MODULE_PARM_DESC(dvb_mfe_wait_time, "Wait up to <mfe_wait_time> seconds on open(
* FESTATE_LOSTLOCK. When the lock has been lost, and we're searching it again.
*/
#define DVB_FE_NO_EXIT 0
#define DVB_FE_NORMAL_EXIT 1
#define DVB_FE_DEVICE_REMOVED 2
static DEFINE_MUTEX(frontend_mutex);
struct dvb_frontend_private {
@ -497,7 +501,7 @@ static int dvb_frontend_is_exiting(struct dvb_frontend *fe)
{
struct dvb_frontend_private *fepriv = fe->frontend_priv;
if (fepriv->exit)
if (fepriv->exit != DVB_FE_NO_EXIT)
return 1;
if (fepriv->dvbdev->writers == 1)
@ -559,7 +563,7 @@ restart:
if (kthread_should_stop() || dvb_frontend_is_exiting(fe)) {
/* got signal or quitting */
fepriv->exit = 1;
fepriv->exit = DVB_FE_NORMAL_EXIT;
break;
}
@ -673,7 +677,10 @@ restart:
}
fepriv->thread = NULL;
fepriv->exit = 0;
if (kthread_should_stop())
fepriv->exit = DVB_FE_DEVICE_REMOVED;
else
fepriv->exit = DVB_FE_NO_EXIT;
mb();
dvb_frontend_wakeup(fe);
@ -686,7 +693,7 @@ static void dvb_frontend_stop(struct dvb_frontend *fe)
dprintk ("%s\n", __func__);
fepriv->exit = 1;
fepriv->exit = DVB_FE_NORMAL_EXIT;
mb();
if (!fepriv->thread)
@ -755,7 +762,7 @@ static int dvb_frontend_start(struct dvb_frontend *fe)
dprintk ("%s\n", __func__);
if (fepriv->thread) {
if (!fepriv->exit)
if (fepriv->exit == DVB_FE_NO_EXIT)
return 0;
else
dvb_frontend_stop (fe);
@ -767,7 +774,7 @@ static int dvb_frontend_start(struct dvb_frontend *fe)
return -EINTR;
fepriv->state = FESTATE_IDLE;
fepriv->exit = 0;
fepriv->exit = DVB_FE_NO_EXIT;
fepriv->thread = NULL;
mb();
@ -1490,7 +1497,7 @@ static int dvb_frontend_ioctl(struct inode *inode, struct file *file,
dprintk("%s (%d)\n", __func__, _IOC_NR(cmd));
if (fepriv->exit)
if (fepriv->exit != DVB_FE_NO_EXIT)
return -ENODEV;
if ((file->f_flags & O_ACCMODE) == O_RDONLY &&
@ -1916,6 +1923,8 @@ static int dvb_frontend_open(struct inode *inode, struct file *file)
int ret;
dprintk ("%s\n", __func__);
if (fepriv->exit == DVB_FE_DEVICE_REMOVED)
return -ENODEV;
if (adapter->mfe_shared) {
mutex_lock (&adapter->mfe_lock);
@ -2008,7 +2017,7 @@ static int dvb_frontend_release(struct inode *inode, struct file *file)
ret = dvb_generic_release (inode, file);
if (dvbdev->users == -1) {
if (fepriv->exit == 1) {
if (fepriv->exit != DVB_FE_NO_EXIT) {
fops_put(file->f_op);
file->f_op = NULL;
wake_up(&dvbdev->wait_queue);