[PATCH] ath:Release resources for structure pointer, ar if error pointing device in the function, ath10k_core_register_work

[PATCH] ath:Release resources for structure pointer, ar if error pointing device in the function, ath10k_core_register_work

[Nicholas Krause]

Releases resources and deregisters the stucture pointer ar passed by the caller to the function, ath10k_core_register_work
if unable to probe the structure pointer successfully with a call to ath10k_core_probe_fw. Further more if this happerns
we must first jump to the label err for the goto statement required to jump to handle this particular error in the function,
ath10k_core_register_work.  After we are in the correct error section we must free the resources for the structure pointer,ar
with a call to the function,  ath10k_core_unregister to free resources allocated for the structure pointer,ar.

Signed-off-by: Nicholas Krause <xerofoify@gmail.com>
---
 drivers/net/wireless/ath/ath10k/core.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/drivers/net/wireless/ath/ath10k/core.c b/drivers/net/wireless/ath/ath10k/core.c
index 310e12b..8b2ca25 100644
--- a/drivers/net/wireless/ath/ath10k/core.c
+++ b/drivers/net/wireless/ath/ath10k/core.c
@@ -1307,9 +1307,7 @@ err_unregister_mac:
 err_release_fw:
 	ath10k_core_free_firmware_files(ar);
 err:
-	/* TODO: It's probably a good idea to release device from the driver
-	 * but calling device_release_driver() here will cause a deadlock.
-	 */
+	ath10k_core_unregister(ar);
 	return;
 }
 
-- 
2.1.0

Re: [PATCH] ath:Release resources for structure pointer, ar if error pointing device in the function, ath10k_core_register_work

[Michal Kazior]

On 3 March 2015 at 03:36, Nicholas Krause <xerofoify@gmail.com> wrote:
> Releases resources and deregisters the stucture pointer ar passed by the caller to the function, ath10k_core_register_work
> if unable to probe the structure pointer successfully with a call to ath10k_core_probe_fw. Further more if this happerns
> we must first jump to the label err for the goto statement required to jump to handle this particular error in the function,
> ath10k_core_register_work.  After we are in the correct error section we must free the resources for the structure pointer,ar
> with a call to the function,  ath10k_core_unregister to free resources allocated for the structure pointer,ar.
>
> Signed-off-by: Nicholas Krause <xerofoify@gmail.com>
> ---
>  drivers/net/wireless/ath/ath10k/core.c | 4 +---
>  1 file changed, 1 insertion(+), 3 deletions(-)
>
> diff --git a/drivers/net/wireless/ath/ath10k/core.c b/drivers/net/wireless/ath/ath10k/core.c
> index 310e12b..8b2ca25 100644
> --- a/drivers/net/wireless/ath/ath10k/core.c
> +++ b/drivers/net/wireless/ath/ath10k/core.c
> @@ -1307,9 +1307,7 @@ err_unregister_mac:
>  err_release_fw:
>         ath10k_core_free_firmware_files(ar);
>  err:
> -       /* TODO: It's probably a good idea to release device from the driver
> -        * but calling device_release_driver() here will cause a deadlock.
> -        */
> +       ath10k_core_unregister(ar);
>         return;
>  }

Did you test this? This will deadlock. ath10k_core_unregister() tries
to cancel ar->register_work. This won't work if you call it from the
worker itself. Moreover if I ignore the deadlock
ath10k_core_unregister() would do nothing else in this context because
ATH10K_FLAG_CORE_REGISTERED wouldn't be even set.

If you're interested in dealing with this TODO I suggest you read
through the original thread which led to the current state of affairs:

  http://www.spinics.net/lists/linux-wireless/msg124004.html


Michał

Re: [PATCH] ath:Release resources for structure pointer, ar if error pointing device in the function, ath10k_core_register_work

[nick]

On 2015-03-03 01:40 AM, Michal Kazior wrote:
> On 3 March 2015 at 03:36, Nicholas Krause <xerofoify@gmail.com> wrote:
>> Releases resources and deregisters the stucture pointer ar passed by the caller to the function, ath10k_core_register_work
>> if unable to probe the structure pointer successfully with a call to ath10k_core_probe_fw. Further more if this happerns
>> we must first jump to the label err for the goto statement required to jump to handle this particular error in the function,
>> ath10k_core_register_work.  After we are in the correct error section we must free the resources for the structure pointer,ar
>> with a call to the function,  ath10k_core_unregister to free resources allocated for the structure pointer,ar.
>>
>> Signed-off-by: Nicholas Krause <xerofoify@gmail.com>
>> ---
>>  drivers/net/wireless/ath/ath10k/core.c | 4 +---
>>  1 file changed, 1 insertion(+), 3 deletions(-)
>>
>> diff --git a/drivers/net/wireless/ath/ath10k/core.c b/drivers/net/wireless/ath/ath10k/core.c
>> index 310e12b..8b2ca25 100644
>> --- a/drivers/net/wireless/ath/ath10k/core.c
>> +++ b/drivers/net/wireless/ath/ath10k/core.c
>> @@ -1307,9 +1307,7 @@ err_unregister_mac:
>>  err_release_fw:
>>         ath10k_core_free_firmware_files(ar);
>>  err:
>> -       /* TODO: It's probably a good idea to release device from the driver
>> -        * but calling device_release_driver() here will cause a deadlock.
>> -        */
>> +       ath10k_core_unregister(ar);
>>         return;
>>  }
> 
> Did you test this? This will deadlock. ath10k_core_unregister() tries
> to cancel ar->register_work. This won't work if you call it from the
> worker itself. Moreover if I ignore the deadlock
> ath10k_core_unregister() would do nothing else in this context because
> ATH10K_FLAG_CORE_REGISTERED wouldn't be even set.
> 
> If you're interested in dealing with this TODO I suggest you read
> through the original thread which led to the current state of affairs:
> 
>   http://www.spinics.net/lists/linux-wireless/msg124004.html
> 
> 
> Michał
> 
Michal,
Thanks for the info and the thread related to this issue. After reading it I was wondering if we can test my
patch on actual hardware using this driver with my patch included in order to see what issues are still there.
I don't have the hardware lying around for this but if someone can test my patch out and see where there are
still deadlock issues or other bugs to my patch I am certain I will be able to figure this out.
Thanks,
Nick
P.S. I am a student so my budget for test hardware is a little thin. :(

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