Skip to contentSkip to conversation

dvb frontend lockup

PATCH In review matthieu castet 2 participants 5 messages Mar 21, 2010 – May 5, 2010 Media (V4L/DVB)

lore
Share & tools
lore

matthieu castet

author
#0 lore raw

Hi,

With my current kernel (2.6.32), if my dvb device is removed while in use, I got [1].

After checking the source code, the problem seems to happen also in master :

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.

Matthieu

[ 4920.484047] khubd         D c2008000     0   198      2 0x00000000
[ 4920.484056]  f64c8000 00000046 00000000 c2008000 00000004 c13fa000 c13fa000 f
64c8000
[ 4920.484066]  f64c81bc c2008000 00000000 d9d9dce6 00000452 00000001 f64c8000 c
102daad
[ 4920.484075]  00100100 f64c81bc 00000286 f0a7ccc0 f0913404 f0cba404 f644de58 f
092b0a8
[ 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
author
#1 lore raw

PATCH 1/1 fix dvb frontend lockup

Quoted 43 lines · matthieu castet

Hi,

With my current kernel (2.6.32), if my dvb device is removed while in use, I got [1].

After checking the source code, the problem seems to happen also in master :

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.

Matthieu

[ 4920.484047] khubd         D c2008000     0   198      2 0x00000000
[ 4920.484056]  f64c8000 00000046 00000000 c2008000 00000004 c13fa000 c13fa000 f
64c8000
[ 4920.484066]  f64c81bc c2008000 00000000 d9d9dce6 00000452 00000001 f64c8000 c
102daad
[ 4920.484075]  00100100 f64c81bc 00000286 f0a7ccc0 f0913404 f0cba404 f644de58 f
092b0a8
[ 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
Quoted 9 lines
[ 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

Here a patch that fix the issue

Signed-off-by Matthieu CASTET <[email protected]>
linux/drivers/media/dvb/dvb-core/dvb_frontend.c +7 -2
@@ -686,7 +686,10 @@
 	}
 
 	fepriv->thread = NULL;
-	fepriv->exit = 0;
+	if (kthread_should_stop())
+		fepriv->exit = 2;
+	else
+		fepriv->exit = 0;
 	mb();
 
 	dvb_frontend_wakeup(fe);

@@ -1929,6 +1932,8 @@
 	int ret;
 
 	dprintk ("%s\n", __func__);
+	if (fepriv->exit == 2)
+		return -ENODEV;
 
 	if (adapter->mfe_shared) {
 		mutex_lock (&adapter->mfe_lock);

@@ -2021,7 +2026,7 @@
 	ret = dvb_generic_release (inode, file);
 
 	if (dvbdev->users == -1) {
-		if (fepriv->exit == 1) {
+		if (fepriv->exit) {
 			fops_put(file->f_op);
 			file->f_op = NULL;
 			wake_up(&dvbdev->wait_queue);
author
#2 lore raw

Re: [PATCH] fix dvb frontend lockup

Quoted 53 lines · matthieu castet
Quoted 43 lines · matthieu castet

Hi,

With my current kernel (2.6.32), if my dvb device is removed while in use, I got [1].

After checking the source code, the problem seems to happen also in master :

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.

Matthieu

[ 4920.484047] khubd         D c2008000     0   198      2 0x00000000
[ 4920.484056]  f64c8000 00000046 00000000 c2008000 00000004 c13fa000 c13fa000 f
64c8000
[ 4920.484066]  f64c81bc c2008000 00000000 d9d9dce6 00000452 00000001 f64c8000 c
102daad
[ 4920.484075]  00100100 f64c81bc 00000286 f0a7ccc0 f0913404 f0cba404 f644de58 f
092b0a8
[ 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
Quoted 9 lines
[ 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
Quoted 5 lines

Here a patch that fix the issue

Signed-off-by Matthieu CASTET <[email protected]>

Any news on that

#3 lore raw

Re: [PATCH] fix dvb frontend lockup

In reply to matthieu castet

Hi Matthieu,

Em Sat, 27 Mar 2010 23:04:58 +0100
matthieu castet <[email protected]> escreveu:

Quoted 75 lines

Etiquetas: NonJunk, unknown-1
From: matthieu castet <[email protected]>
To: [email protected]
Subject: [PATCH] fix dvb frontend lockup
Date: Sat, 27 Mar 2010 23:04:58 +0100
Sender: [email protected]
User-Agent: Mozilla/5.0 (X11; U; Linux i686; fr; rv:1.8.1.23) Gecko/20090823 SeaMonkey/1.1.18

Quoted 49 lines · matthieu castet

Hi,

With my current kernel (2.6.32), if my dvb device is removed while in use, I got [1].

After checking the source code, the problem seems to happen also in master :

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.

Matthieu

[ 4920.484047] khubd         D c2008000     0   198      2 0x00000000
[ 4920.484056]  f64c8000 00000046 00000000 c2008000 00000004 c13fa000 
c13fa000 f
64c8000
[ 4920.484066]  f64c81bc c2008000 00000000 d9d9dce6 00000452 00000001 
f64c8000 c
102daad
[ 4920.484075]  00100100 f64c81bc 00000286 f0a7ccc0 f0913404 f0cba404 
f644de58 f
092b0a8
[ 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
Quoted 9 lines
[ 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

Here a patch that fix the issue

Signed-off-by Matthieu CASTET <[email protected]>

linux/drivers/media/dvb/dvb-core/dvb_frontend.c line 690

Quoted 6 lines
linux/drivers/media/dvb/dvb-core/dvb_frontend.c +2 -1
@@ -686,7 +686,10 @@
 	}
 
 	fepriv->thread = NULL;
-	fepriv->exit = 0;
+	if (kthread_should_stop())
+		fepriv->exit = 2;

Your patch makes sense for me. However, using a "magic" 2 value for exit will not be clear enough that this means that the device got removed. The better is to define something like:

#define DVB_FE_NORMAL_EXIT 1
#define DVB_FE_DEVICE_REMOVED 2

And use either one of the macro values for fepriv->exit. This will be clear for those that may later need to touch on that code.

Quoted 23 lines
linux/drivers/media/dvb/dvb-core/dvb_frontend.c +5 -1
+	else
+		fepriv->exit = 0;
 	mb();
 
 	dvb_frontend_wakeup(fe);

@@ -1929,6 +1932,8 @@
 	int ret;
 
 	dprintk ("%s\n", __func__);
+	if (fepriv->exit == 2)
+		return -ENODEV;
 
 	if (adapter->mfe_shared) {
 		mutex_lock (&adapter->mfe_lock);

@@ -2021,7 +2026,7 @@
 	ret = dvb_generic_release (inode, file);
 
 	if (dvbdev->users == -1) {
-		if (fepriv->exit == 1) {
+		if (fepriv->exit) {
 			fops_put(file->f_op);
 			file->f_op = NULL;
 			wake_up(&dvbdev->wait_queue)
Signature · 2 lines
Cheers,
Mauro
author
#4 lore raw

Re: [PATCH] fix dvb frontend lockup

Quoted 42 lines · matthieu castet

Hi,

With my current kernel (2.6.32), if my dvb device is removed while in use, I got [1].

After checking the source code, the problem seems to happen also in master :

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.

Matthieu

[ 4920.484047] khubd         D c2008000     0   198      2 0x00000000
[ 4920.484056]  f64c8000 00000046 00000000 c2008000 00000004 c13fa000 c13fa000 f
64c8000
[ 4920.484066]  f64c81bc c2008000 00000000 d9d9dce6 00000452 00000001 f64c8000 c
102daad
[ 4920.484075]  00100100 f64c81bc 00000286 f0a7ccc0 f0913404 f0cba404 f644de58 f
092b0a8
[ 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
Quoted 9 lines
[ 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

Here a patch that fix the issue

Signed-off-by Matthieu CASTET <[email protected]>
drivers/media/dvb/dvb-core/dvb_frontend.c +17 -8
index 55ea260..6932def 100644
@@ -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);