Re: [PATCH v2] staging: bcm2835-audio: Release resources on module_exit()

2018-03-21 Thread Kirill Marinushkin 
On 03/21/18 16:03, Andy Shevchenko wrote:
> On Thu, Mar 15, 2018 at 7:57 AM, Kirill Marinushkin
>  wrote:
>> On 03/13/18 22:23, Andy Shevchenko wrote:
>>> On Tue, Mar 13, 2018 at 9:34 PM, Kirill Marinushkin
>>>  wrote:
 In the current implementation, `rmmod snd_bcm2835` does not release
 resources properly. It causes an oops when trying to list sound devices.

 This commit fixes it.
>>> Nice catch!
>>>
>>> See my comments below.
>>>
  static void snd_devm_unregister_child(struct device *dev, void *res)
  {
 struct device *childdev = *(struct device **)res;
 +   struct bcm2835_chip *chip = dev_get_drvdata(childdev);
 +   struct snd_card *card = chip->card;
 +
 +   snd_card_free(card);
 +   dev_set_drvdata(childdev, NULL);
>>> AFAIU this is done by device core.
>> Maybe you are right. But I don't know, which function in the device core 
>> does it.
>> It is safe to have this line. So, I suggest to keep it.
> Please, remove.
> If you don't know, perhaps you need to spend more time on doing homework?

You are right, I actually should pay more attention to this detail.
I will remove this line and send as a patch v3

> % git grep -n -w dev_set_drvdata -- drivers/base/dd.c
> drivers/base/dd.c:469:  dev_set_drvdata(dev, NULL);
> drivers/base/dd.c:499:  dev_set_drvdata(dev, NULL);
> drivers/base/dd.c:902:  dev_set_drvdata(dev, NULL);
>
> Last one is the point of your interest.
>

Re: [PATCH v2] staging: bcm2835-audio: Release resources on module_exit()

2018-03-21 Thread Kirill Marinushkin 
On 03/21/18 16:03, Andy Shevchenko wrote:
> On Thu, Mar 15, 2018 at 7:57 AM, Kirill Marinushkin
>  wrote:
>> On 03/13/18 22:23, Andy Shevchenko wrote:
>>> On Tue, Mar 13, 2018 at 9:34 PM, Kirill Marinushkin
>>>  wrote:
 In the current implementation, `rmmod snd_bcm2835` does not release
 resources properly. It causes an oops when trying to list sound devices.

 This commit fixes it.
>>> Nice catch!
>>>
>>> See my comments below.
>>>
  static void snd_devm_unregister_child(struct device *dev, void *res)
  {
 struct device *childdev = *(struct device **)res;
 +   struct bcm2835_chip *chip = dev_get_drvdata(childdev);
 +   struct snd_card *card = chip->card;
 +
 +   snd_card_free(card);
 +   dev_set_drvdata(childdev, NULL);
>>> AFAIU this is done by device core.
>> Maybe you are right. But I don't know, which function in the device core 
>> does it.
>> It is safe to have this line. So, I suggest to keep it.
> Please, remove.
> If you don't know, perhaps you need to spend more time on doing homework?

You are right, I actually should pay more attention to this detail.
I will remove this line and send as a patch v3

> % git grep -n -w dev_set_drvdata -- drivers/base/dd.c
> drivers/base/dd.c:469:  dev_set_drvdata(dev, NULL);
> drivers/base/dd.c:499:  dev_set_drvdata(dev, NULL);
> drivers/base/dd.c:902:  dev_set_drvdata(dev, NULL);
>
> Last one is the point of your interest.
>

Re: [PATCH v2] staging: bcm2835-audio: Release resources on module_exit()

2018-03-21 Thread Andy Shevchenko 
On Thu, Mar 15, 2018 at 7:57 AM, Kirill Marinushkin
 wrote:
> On 03/13/18 22:23, Andy Shevchenko wrote:
>> On Tue, Mar 13, 2018 at 9:34 PM, Kirill Marinushkin
>>  wrote:
>>> In the current implementation, `rmmod snd_bcm2835` does not release
>>> resources properly. It causes an oops when trying to list sound devices.
>>>
>>> This commit fixes it.
>> Nice catch!
>>
>> See my comments below.
>>
>>>  static void snd_devm_unregister_child(struct device *dev, void *res)
>>>  {
>>> struct device *childdev = *(struct device **)res;
>>> +   struct bcm2835_chip *chip = dev_get_drvdata(childdev);
>>> +   struct snd_card *card = chip->card;
>>> +
>>> +   snd_card_free(card);
>>> +   dev_set_drvdata(childdev, NULL);
>> AFAIU this is done by device core.
>
> Maybe you are right. But I don't know, which function in the device core does 
> it.
> It is safe to have this line. So, I suggest to keep it.

Please, remove.
If you don't know, perhaps you need to spend more time on doing homework?

% git grep -n -w dev_set_drvdata -- drivers/base/dd.c
drivers/base/dd.c:469:  dev_set_drvdata(dev, NULL);
drivers/base/dd.c:499:  dev_set_drvdata(dev, NULL);
drivers/base/dd.c:902:  dev_set_drvdata(dev, NULL);

Last one is the point of your interest.

-- 
With Best Regards,
Andy Shevchenko

Re: [PATCH v2] staging: bcm2835-audio: Release resources on module_exit()

2018-03-21 Thread Andy Shevchenko 
On Thu, Mar 15, 2018 at 7:57 AM, Kirill Marinushkin
 wrote:
> On 03/13/18 22:23, Andy Shevchenko wrote:
>> On Tue, Mar 13, 2018 at 9:34 PM, Kirill Marinushkin
>>  wrote:
>>> In the current implementation, `rmmod snd_bcm2835` does not release
>>> resources properly. It causes an oops when trying to list sound devices.
>>>
>>> This commit fixes it.
>> Nice catch!
>>
>> See my comments below.
>>
>>>  static void snd_devm_unregister_child(struct device *dev, void *res)
>>>  {
>>> struct device *childdev = *(struct device **)res;
>>> +   struct bcm2835_chip *chip = dev_get_drvdata(childdev);
>>> +   struct snd_card *card = chip->card;
>>> +
>>> +   snd_card_free(card);
>>> +   dev_set_drvdata(childdev, NULL);
>> AFAIU this is done by device core.
>
> Maybe you are right. But I don't know, which function in the device core does 
> it.
> It is safe to have this line. So, I suggest to keep it.

Please, remove.
If you don't know, perhaps you need to spend more time on doing homework?

% git grep -n -w dev_set_drvdata -- drivers/base/dd.c
drivers/base/dd.c:469:  dev_set_drvdata(dev, NULL);
drivers/base/dd.c:499:  dev_set_drvdata(dev, NULL);
drivers/base/dd.c:902:  dev_set_drvdata(dev, NULL);

Last one is the point of your interest.

-- 
With Best Regards,
Andy Shevchenko

Re: [PATCH v2] staging: bcm2835-audio: Release resources on module_exit()

2018-03-14 Thread Kirill Marinushkin 
On 03/13/18 22:23, Andy Shevchenko wrote:
> On Tue, Mar 13, 2018 at 9:34 PM, Kirill Marinushkin
>  wrote:
>> In the current implementation, `rmmod snd_bcm2835` does not release
>> resources properly. It causes an oops when trying to list sound devices.
>>
>> This commit fixes it.
> Nice catch!
>
> See my comments below.
>
>>  static void snd_devm_unregister_child(struct device *dev, void *res)
>>  {
>> struct device *childdev = *(struct device **)res;
>> +   struct bcm2835_chip *chip = dev_get_drvdata(childdev);
>> +   struct snd_card *card = chip->card;
>> +
>> +   snd_card_free(card);
>> +   dev_set_drvdata(childdev, NULL);
> AFAIU this is done by device core.

Maybe you are right. But I don't know, which function in the device core does 
it.
It is safe to have this line. So, I suggest to keep it.

>
>> device_unregister(childdev);
>>  }
>> +static void snd_devm_release(struct device *dev)
>> +{
>> +   struct bcm2835_chip *chip = dev_get_drvdata(dev);
>> +
>> +   kfree(chip);
>> +}
>
>>  /* chip-specific constructor
>> @@ -122,7 +136,7 @@ static int snd_bcm2835_create(struct snd_card *card,
>>
>> err = snd_device_new(card, SNDRV_DEV_LOWLEVEL, chip, );
>> if (err) {
>> -   snd_bcm2835_free(chip);
>> +   kfree(chip);
> Do you call device_register() inside snd_device_new()?
> In this case you might need put_device() here instead of simple kfree().

No, from what I see, device_register() does not happen inside snd_device_new().

>> return err;
>> }

Re: [PATCH v2] staging: bcm2835-audio: Release resources on module_exit()

2018-03-14 Thread Kirill Marinushkin 
On 03/13/18 22:23, Andy Shevchenko wrote:
> On Tue, Mar 13, 2018 at 9:34 PM, Kirill Marinushkin
>  wrote:
>> In the current implementation, `rmmod snd_bcm2835` does not release
>> resources properly. It causes an oops when trying to list sound devices.
>>
>> This commit fixes it.
> Nice catch!
>
> See my comments below.
>
>>  static void snd_devm_unregister_child(struct device *dev, void *res)
>>  {
>> struct device *childdev = *(struct device **)res;
>> +   struct bcm2835_chip *chip = dev_get_drvdata(childdev);
>> +   struct snd_card *card = chip->card;
>> +
>> +   snd_card_free(card);
>> +   dev_set_drvdata(childdev, NULL);
> AFAIU this is done by device core.

Maybe you are right. But I don't know, which function in the device core does 
it.
It is safe to have this line. So, I suggest to keep it.

>
>> device_unregister(childdev);
>>  }
>> +static void snd_devm_release(struct device *dev)
>> +{
>> +   struct bcm2835_chip *chip = dev_get_drvdata(dev);
>> +
>> +   kfree(chip);
>> +}
>
>>  /* chip-specific constructor
>> @@ -122,7 +136,7 @@ static int snd_bcm2835_create(struct snd_card *card,
>>
>> err = snd_device_new(card, SNDRV_DEV_LOWLEVEL, chip, );
>> if (err) {
>> -   snd_bcm2835_free(chip);
>> +   kfree(chip);
> Do you call device_register() inside snd_device_new()?
> In this case you might need put_device() here instead of simple kfree().

No, from what I see, device_register() does not happen inside snd_device_new().

>> return err;
>> }

Re: [PATCH v2] staging: bcm2835-audio: Release resources on module_exit()

2018-03-13 Thread Andy Shevchenko 
On Tue, Mar 13, 2018 at 9:34 PM, Kirill Marinushkin
 wrote:
> In the current implementation, `rmmod snd_bcm2835` does not release
> resources properly. It causes an oops when trying to list sound devices.
>
> This commit fixes it.

Nice catch!

See my comments below.

>  static void snd_devm_unregister_child(struct device *dev, void *res)
>  {
> struct device *childdev = *(struct device **)res;
> +   struct bcm2835_chip *chip = dev_get_drvdata(childdev);
> +   struct snd_card *card = chip->card;
> +
> +   snd_card_free(card);

> +   dev_set_drvdata(childdev, NULL);

AFAIU this is done by device core.

> device_unregister(childdev);
>  }

> +static void snd_devm_release(struct device *dev)
> +{
> +   struct bcm2835_chip *chip = dev_get_drvdata(dev);
> +
> +   kfree(chip);
> +}


>  /* chip-specific constructor
> @@ -122,7 +136,7 @@ static int snd_bcm2835_create(struct snd_card *card,
>
> err = snd_device_new(card, SNDRV_DEV_LOWLEVEL, chip, );
> if (err) {
> -   snd_bcm2835_free(chip);
> +   kfree(chip);

Do you call device_register() inside snd_device_new()?
In this case you might need put_device() here instead of simple kfree().

> return err;
> }

-- 
With Best Regards,
Andy Shevchenko

Re: [PATCH v2] staging: bcm2835-audio: Release resources on module_exit()

2018-03-13 Thread Andy Shevchenko 
On Tue, Mar 13, 2018 at 9:34 PM, Kirill Marinushkin
 wrote:
> In the current implementation, `rmmod snd_bcm2835` does not release
> resources properly. It causes an oops when trying to list sound devices.
>
> This commit fixes it.

Nice catch!

See my comments below.

>  static void snd_devm_unregister_child(struct device *dev, void *res)
>  {
> struct device *childdev = *(struct device **)res;
> +   struct bcm2835_chip *chip = dev_get_drvdata(childdev);
> +   struct snd_card *card = chip->card;
> +
> +   snd_card_free(card);

> +   dev_set_drvdata(childdev, NULL);

AFAIU this is done by device core.

> device_unregister(childdev);
>  }

> +static void snd_devm_release(struct device *dev)
> +{
> +   struct bcm2835_chip *chip = dev_get_drvdata(dev);
> +
> +   kfree(chip);
> +}


>  /* chip-specific constructor
> @@ -122,7 +136,7 @@ static int snd_bcm2835_create(struct snd_card *card,
>
> err = snd_device_new(card, SNDRV_DEV_LOWLEVEL, chip, );
> if (err) {
> -   snd_bcm2835_free(chip);
> +   kfree(chip);

Do you call device_register() inside snd_device_new()?
In this case you might need put_device() here instead of simple kfree().

> return err;
> }

-- 
With Best Regards,
Andy Shevchenko

[PATCH v2] staging: bcm2835-audio: Release resources on module_exit()

2018-03-13 Thread Kirill Marinushkin 
In the current implementation, `rmmod snd_bcm2835` does not release
resources properly. It causes an oops when trying to list sound devices.

This commit fixes it.

The details WRT allocation / free are described below.

Device structure WRT allocation:

pdev
  \childdev[]
\card
  \chip
\pcm
\ctl

Allocation / register sequence:

* childdev: devm_kzalloc  - freed during driver detach
* childdev: device_initialize - freed during device_unregister
* pdev: devres_alloc  - freed during driver detach
* childdev: device_add- removed during device_unregister
* pdev, childdev: devres_add  - freed during driver detach
* card: snd_card_new  - freed during snd_card_free
* chip: kzalloc   - freed during kfree
* card, chip: snd_device_new  - freed during snd_device_free
* chip: new_pcm   - TODO: free pcm
* chip: new_ctl   - TODO: free ctl
* card: snd_card_register - unregistered during snd_card_free

Free / unregister sequence:

* card: snd_card_free
* card, chip: snd_device_free
* childdev: device_unregister
* chip: kfree

Steps to reproduce the issue before this commit:


$ rmmod snd_bcm2835
$ aplay -L
[  138.648130] Unable to handle kernel paging request at virtual address 
7f1343c0
[  138.660415] pgd = ad8f
[  138.665567] [7f1343c0] *pgd=3864c811, *pte=, *ppte=
[  138.674887] Internal error: Oops: 7 [#1] SMP ARM
[  138.683571] Modules linked in: sha256_generic cfg80211 rfkill snd_pcm 
snd_timer
 snd fixed uio_pdrv_genirq uio ip_tables x_tables ipv6 [last unloaded: 
snd_bcm2835
]
[  138.706594] CPU: 3 PID: 463 Comm: aplay Tainted: GWC   
4.15.0-rc1-v
7+ #6
[  138.719833] Hardware name: BCM2835
[  138.726016] task: b877ac00 task.stack: aebec000
[  138.733408] PC is at try_module_get+0x38/0x24c
[  138.740813] LR is at snd_ctl_open+0x58/0x194 [snd]
[  138.748485] pc : [<801c4d5c>]lr : [<7f0e6b2c>]psr: 2013
[  138.757709] sp : aebedd60  ip : aebedd88  fp : aebedd84
[  138.765884] r10:   r9 : 0004  r8 : 7f0ed440
[  138.774040] r7 : b7e469b0  r6 : 7f0e6b2c  r5 : afd91900  r4 : 7f1343c0
[  138.783571] r3 : aebec000  r2 : 0001  r1 : b877ac00  r0 : 7f1343c0
[  138.793084] Flags: nzCv  IRQs on  FIQs on  Mode SVC_32  ISA ARM  Segment user
[  138.803300] Control: 10c5387d  Table: 2d8f006a  DAC: 0055
[  138.812064] Process aplay (pid: 463, stack limit = 0xaebec210)
[  138.820868] Stack: (0xaebedd60 to 0xaebee000)
[  138.828207] dd60:  b848d000 afd91900  b7e469b0 7f0ed440 
aebedda4 aebedd88
[  138.842371] dd80: 7f0e6b2c 801c4d30 afd91900 7f0ea4dc  b7e469b0 
aebeddcc aebedda8
[  138.856611] dda0: 7f0e250c 7f0e6ae0 7f0e2464 b8478ec0 b7e469b0 afd91900 
7f0ea388 
[  138.870864] ddc0: aebeddf4 aebeddd0 802ce590 7f0e2470 8090ab64 afd91900 
afd91900 b7e469b0
[  138.885301] dde0: afd91908 802ce4e4 aebede1c aebeddf8 802c57b4 802ce4f0 
afd91900 aebedea8
[  138.900110] de00: b7fa4c00   0004 aebede3c aebede20 
802c6ba8 802c56b4
[  138.915260] de20: aebedea8  aebedf5c  aebedea4 aebede40 
802d9a68 802c6b58
[  138.930661] de40: b874ddd0   0001 0041  
afd91900 aebede70
[  138.946402] de60:   0002 b7e469b0 b8a87610 b8d6ab80 
801852f8 0008
[  138.962314] de80: aebedf5c aebedea8 0001 80108464 aebec000  
aebedf4c aebedea8
[  138.978414] dea0: 802dacd4 802d970c b8a87610 b8d6ab80 a7982bc6 0009 
af363019 b9231480
[  138.994617] dec0:  b8c038a0 b7e469b0 0101 0002 0238 
 
[  139.010823] dee0:  aebedee8 0008 000f aebedf3c aebedf00 
802ed7e4 80843f94
[  139.027025] df00: 0003 0008 b9231490 b9231480  0008 
af363000 
[  139.043229] df20: 0005 0002 ff9c  0008 ff9c 
af363000 0003
[  139.059430] df40: aebedf94 aebedf50 802c6f70 802dac70 aebec000  
0001 
[  139.075629] df60: 0002 0004 0100 0001 7ebe577c 0002e038 
 0005
[  139.091828] df80: 80108464 aebec000 aebedfa4 aebedf98 802c7060 802c6e6c 
 aebedfa8
[  139.108025] dfa0: 801082c0 802c7040 7ebe577c 0002e038 7ebe577c 0008 
0b98 e81c8400
[  139.124222] dfc0: 7ebe577c 0002e038  0005 7ebe57e4 00a20af8 
7ebe57f0 76f87394
[  139.140419] dfe0:  7ebe55c4 76ec88e8 76df1d9c 6010 7ebe577c 
 
[  139.156715] [<801c4d5c>] (try_module_get) from [<7f0e6b2c>] 
(snd_ctl_open+0x58/0x194 [snd])
[  139.173222] [<7f0e6b2c>] (snd_ctl_open [snd]) from [<7f0e250c>] 
(snd_open+0xa8/0x14c [snd])
[  139.189683] [<7f0e250c>] (snd_open [snd]) from [<802ce590>] 
(chrdev_open+0xac/0x188)
[  139.205465] [<802ce590>] (chrdev_open) from [<802c57b4>] 
(do_dentry_open+0x10c/0x314)
[  139.221347] [<802c57b4>] (do_dentry_open) from [<802c6ba8>] 
(vfs_open+0x5c/0x88)
[  139.236788] [<802c6ba8>] (vfs_open) from [<802d9a68>]

[PATCH v2] staging: bcm2835-audio: Release resources on module_exit()

2018-03-13 Thread Kirill Marinushkin 
In the current implementation, `rmmod snd_bcm2835` does not release
resources properly. It causes an oops when trying to list sound devices.

This commit fixes it.

The details WRT allocation / free are described below.

Device structure WRT allocation:

pdev
  \childdev[]
\card
  \chip
\pcm
\ctl

Allocation / register sequence:

* childdev: devm_kzalloc  - freed during driver detach
* childdev: device_initialize - freed during device_unregister
* pdev: devres_alloc  - freed during driver detach
* childdev: device_add- removed during device_unregister
* pdev, childdev: devres_add  - freed during driver detach
* card: snd_card_new  - freed during snd_card_free
* chip: kzalloc   - freed during kfree
* card, chip: snd_device_new  - freed during snd_device_free
* chip: new_pcm   - TODO: free pcm
* chip: new_ctl   - TODO: free ctl
* card: snd_card_register - unregistered during snd_card_free

Free / unregister sequence:

* card: snd_card_free
* card, chip: snd_device_free
* childdev: device_unregister
* chip: kfree

Steps to reproduce the issue before this commit:


$ rmmod snd_bcm2835
$ aplay -L
[  138.648130] Unable to handle kernel paging request at virtual address 
7f1343c0
[  138.660415] pgd = ad8f
[  138.665567] [7f1343c0] *pgd=3864c811, *pte=, *ppte=
[  138.674887] Internal error: Oops: 7 [#1] SMP ARM
[  138.683571] Modules linked in: sha256_generic cfg80211 rfkill snd_pcm 
snd_timer
 snd fixed uio_pdrv_genirq uio ip_tables x_tables ipv6 [last unloaded: 
snd_bcm2835
]
[  138.706594] CPU: 3 PID: 463 Comm: aplay Tainted: GWC   
4.15.0-rc1-v
7+ #6
[  138.719833] Hardware name: BCM2835
[  138.726016] task: b877ac00 task.stack: aebec000
[  138.733408] PC is at try_module_get+0x38/0x24c
[  138.740813] LR is at snd_ctl_open+0x58/0x194 [snd]
[  138.748485] pc : [<801c4d5c>]lr : [<7f0e6b2c>]psr: 2013
[  138.757709] sp : aebedd60  ip : aebedd88  fp : aebedd84
[  138.765884] r10:   r9 : 0004  r8 : 7f0ed440
[  138.774040] r7 : b7e469b0  r6 : 7f0e6b2c  r5 : afd91900  r4 : 7f1343c0
[  138.783571] r3 : aebec000  r2 : 0001  r1 : b877ac00  r0 : 7f1343c0
[  138.793084] Flags: nzCv  IRQs on  FIQs on  Mode SVC_32  ISA ARM  Segment user
[  138.803300] Control: 10c5387d  Table: 2d8f006a  DAC: 0055
[  138.812064] Process aplay (pid: 463, stack limit = 0xaebec210)
[  138.820868] Stack: (0xaebedd60 to 0xaebee000)
[  138.828207] dd60:  b848d000 afd91900  b7e469b0 7f0ed440 
aebedda4 aebedd88
[  138.842371] dd80: 7f0e6b2c 801c4d30 afd91900 7f0ea4dc  b7e469b0 
aebeddcc aebedda8
[  138.856611] dda0: 7f0e250c 7f0e6ae0 7f0e2464 b8478ec0 b7e469b0 afd91900 
7f0ea388 
[  138.870864] ddc0: aebeddf4 aebeddd0 802ce590 7f0e2470 8090ab64 afd91900 
afd91900 b7e469b0
[  138.885301] dde0: afd91908 802ce4e4 aebede1c aebeddf8 802c57b4 802ce4f0 
afd91900 aebedea8
[  138.900110] de00: b7fa4c00   0004 aebede3c aebede20 
802c6ba8 802c56b4
[  138.915260] de20: aebedea8  aebedf5c  aebedea4 aebede40 
802d9a68 802c6b58
[  138.930661] de40: b874ddd0   0001 0041  
afd91900 aebede70
[  138.946402] de60:   0002 b7e469b0 b8a87610 b8d6ab80 
801852f8 0008
[  138.962314] de80: aebedf5c aebedea8 0001 80108464 aebec000  
aebedf4c aebedea8
[  138.978414] dea0: 802dacd4 802d970c b8a87610 b8d6ab80 a7982bc6 0009 
af363019 b9231480
[  138.994617] dec0:  b8c038a0 b7e469b0 0101 0002 0238 
 
[  139.010823] dee0:  aebedee8 0008 000f aebedf3c aebedf00 
802ed7e4 80843f94
[  139.027025] df00: 0003 0008 b9231490 b9231480  0008 
af363000 
[  139.043229] df20: 0005 0002 ff9c  0008 ff9c 
af363000 0003
[  139.059430] df40: aebedf94 aebedf50 802c6f70 802dac70 aebec000  
0001 
[  139.075629] df60: 0002 0004 0100 0001 7ebe577c 0002e038 
 0005
[  139.091828] df80: 80108464 aebec000 aebedfa4 aebedf98 802c7060 802c6e6c 
 aebedfa8
[  139.108025] dfa0: 801082c0 802c7040 7ebe577c 0002e038 7ebe577c 0008 
0b98 e81c8400
[  139.124222] dfc0: 7ebe577c 0002e038  0005 7ebe57e4 00a20af8 
7ebe57f0 76f87394
[  139.140419] dfe0:  7ebe55c4 76ec88e8 76df1d9c 6010 7ebe577c 
 
[  139.156715] [<801c4d5c>] (try_module_get) from [<7f0e6b2c>] 
(snd_ctl_open+0x58/0x194 [snd])
[  139.173222] [<7f0e6b2c>] (snd_ctl_open [snd]) from [<7f0e250c>] 
(snd_open+0xa8/0x14c [snd])
[  139.189683] [<7f0e250c>] (snd_open [snd]) from [<802ce590>] 
(chrdev_open+0xac/0x188)
[  139.205465] [<802ce590>] (chrdev_open) from [<802c57b4>] 
(do_dentry_open+0x10c/0x314)
[  139.221347] [<802c57b4>] (do_dentry_open) from [<802c6ba8>] 
(vfs_open+0x5c/0x88)
[  139.236788] [<802c6ba8>] (vfs_open) from [<802d9a68>]