Re: [PATCH] wfx: avoid flush_workqueue(system_highpri_wq) usage

[Kalle Valo <kvalo@kernel.org>]

Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> writes:

> Flushing system-wide workqueues is dangerous and will be forbidden.
> Replace system_highpri_wq with local wfx_wq.
>
> While we are at it, add missing spi_unregister_driver() call when
> sdio_register_driver() failed.
>
> Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>

[...]

> @@ -473,10 +475,18 @@ static int __init wfx_core_init(void)
>  {
>  	int ret = 0;
>  
> +	wfx_wq = alloc_workqueue("wfx_wq", WQ_HIGHPRI, 0);
> +	if (!wfx_wq)
> +		return -ENOMEM;
>  	if (IS_ENABLED(CONFIG_SPI))
>  		ret = spi_register_driver(&wfx_spi_driver);
>  	if (IS_ENABLED(CONFIG_MMC) && !ret)
>  		ret = sdio_register_driver(&wfx_sdio_driver);
> +	if (ret) {
> +		if (IS_ENABLED(CONFIG_SPI))
> +			spi_unregister_driver(&wfx_spi_driver);
> +		destroy_workqueue(wfx_wq);
> +	}
>  	return ret;
>  }
>  module_init(wfx_core_init);

So now the thread is created every time the module loaded, even if
there's no device available. Also I'm not really a fan of global
variables (wfx_wq). I would rather create a workqueue per device in
wfx_probe() or use the workqueue provided by mac80211.

/**
 * ieee80211_queue_work - add work onto the mac80211 workqueue
 *
 * Drivers and mac80211 use this to add work onto the mac80211 workqueue.
 * This helper ensures drivers are not queueing work when they should not be.
 *
 * @hw: the hardware struct for the interface we are adding work for
 * @work: the work we want to add onto the mac80211 workqueue
 */
void ieee80211_queue_work(struct ieee80211_hw *hw, struct work_struct *work);

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