V4L/DVB: fix dvb frontend lockup
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>
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@ -95,6 +95,10 @@ MODULE_PARM_DESC(dvb_mfe_wait_time, "Wait up to <mfe_wait_time> seconds on open(
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* FESTATE_LOSTLOCK. When the lock has been lost, and we're searching it again.
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*/
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#define DVB_FE_NO_EXIT 0
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#define DVB_FE_NORMAL_EXIT 1
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#define DVB_FE_DEVICE_REMOVED 2
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static DEFINE_MUTEX(frontend_mutex);
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struct dvb_frontend_private {
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@ -497,7 +501,7 @@ static int dvb_frontend_is_exiting(struct dvb_frontend *fe)
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{
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struct dvb_frontend_private *fepriv = fe->frontend_priv;
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if (fepriv->exit)
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if (fepriv->exit != DVB_FE_NO_EXIT)
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return 1;
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if (fepriv->dvbdev->writers == 1)
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@ -559,7 +563,7 @@ restart:
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if (kthread_should_stop() || dvb_frontend_is_exiting(fe)) {
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/* got signal or quitting */
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fepriv->exit = 1;
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fepriv->exit = DVB_FE_NORMAL_EXIT;
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break;
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}
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@ -673,7 +677,10 @@ restart:
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}
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fepriv->thread = NULL;
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fepriv->exit = 0;
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if (kthread_should_stop())
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fepriv->exit = DVB_FE_DEVICE_REMOVED;
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else
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fepriv->exit = DVB_FE_NO_EXIT;
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mb();
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dvb_frontend_wakeup(fe);
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@ -686,7 +693,7 @@ static void dvb_frontend_stop(struct dvb_frontend *fe)
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dprintk ("%s\n", __func__);
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fepriv->exit = 1;
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fepriv->exit = DVB_FE_NORMAL_EXIT;
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mb();
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if (!fepriv->thread)
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@ -755,7 +762,7 @@ static int dvb_frontend_start(struct dvb_frontend *fe)
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dprintk ("%s\n", __func__);
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if (fepriv->thread) {
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if (!fepriv->exit)
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if (fepriv->exit == DVB_FE_NO_EXIT)
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return 0;
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else
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dvb_frontend_stop (fe);
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@ -767,7 +774,7 @@ static int dvb_frontend_start(struct dvb_frontend *fe)
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return -EINTR;
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fepriv->state = FESTATE_IDLE;
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fepriv->exit = 0;
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fepriv->exit = DVB_FE_NO_EXIT;
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fepriv->thread = NULL;
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mb();
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@ -1490,7 +1497,7 @@ static int dvb_frontend_ioctl(struct inode *inode, struct file *file,
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dprintk("%s (%d)\n", __func__, _IOC_NR(cmd));
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if (fepriv->exit)
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if (fepriv->exit != DVB_FE_NO_EXIT)
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return -ENODEV;
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if ((file->f_flags & O_ACCMODE) == O_RDONLY &&
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@ -1916,6 +1923,8 @@ static int dvb_frontend_open(struct inode *inode, struct file *file)
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int ret;
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dprintk ("%s\n", __func__);
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if (fepriv->exit == DVB_FE_DEVICE_REMOVED)
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return -ENODEV;
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if (adapter->mfe_shared) {
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mutex_lock (&adapter->mfe_lock);
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@ -2008,7 +2017,7 @@ static int dvb_frontend_release(struct inode *inode, struct file *file)
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ret = dvb_generic_release (inode, file);
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if (dvbdev->users == -1) {
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if (fepriv->exit == 1) {
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if (fepriv->exit != DVB_FE_NO_EXIT) {
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fops_put(file->f_op);
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file->f_op = NULL;
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wake_up(&dvbdev->wait_queue);
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