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

From: Michal Kazior
Date: Tue Mar 03 2015 - 01:40:39 EST

On 3 March 2015 at 03:36, Nicholas Krause <xerofoify@xxxxxxxxx> 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@xxxxxxxxx>
> ---
> 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:

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