linux-kernel - Re: [RFT/RFC] power_supply: bq2415x_charger: Initialize workqueue before scheduling it

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Message-Id: <201507252349.06519@pali>
Date:	Sat, 25 Jul 2015 23:49:06 +0200
From:	Pali Rohár <pali.rohar@...il.com>
To:	Krzysztof Kozlowski <k.kozlowski@...sung.com>
Cc:	Sebastian Reichel <sre@...nel.org>,
	"Dmitry Eremin-Solenikov" <dbaryshkov@...il.com>,
	David Woodhouse <dwmw2@...radead.org>,
	linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [RFT/RFC] power_supply: bq2415x_charger: Initialize workqueue before scheduling it

On Tuesday 14 July 2015 02:34:13 Krzysztof Kozlowski wrote:
> The driver during probe registers a power supply notifier
> (with bq2415x_notifier_call() callback) and calls it manually right
> after. The notifier callback function schedules driver's workqueue
> (bq->work).
> 
> However the workqueue was initialized after these two events (after
> registering power supply notifier and calling manually the callback).
> 
> When power supply core notified the driver (executing its
> bq2415x_notifier_call() callback) the scheduled workqueue could be
> still uninitialized.
> 
> Signed-off-by: Krzysztof Kozlowski <k.kozlowski@...sung.com>
> Reported-by: Pali Rohár <pali.rohar@...il.com>
> 
> ---
> 
> I don't have the hardware, please test. Additionally I could not find
> the commit which introduced the issue so I did not cc-stable.
> ---
>  drivers/power/bq2415x_charger.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/power/bq2415x_charger.c
> b/drivers/power/bq2415x_charger.c index e98dcb661cc9..527ed0f18796
> 100644
> --- a/drivers/power/bq2415x_charger.c
> +++ b/drivers/power/bq2415x_charger.c
> @@ -1601,6 +1601,7 @@ static int bq2415x_probe(struct i2c_client
> *client, bq->reported_mode = BQ2415X_MODE_OFF;
>  	bq->autotimer = 0;
>  	bq->automode = 0;
> +	INIT_DELAYED_WORK(&bq->work, bq2415x_timer_work);
> 
>  	if (np || ACPI_HANDLE(bq->dev)) {
>  		ret = device_property_read_u32(bq->dev,
> @@ -1677,7 +1678,6 @@ static int bq2415x_probe(struct i2c_client
> *client, dev_info(bq->dev, "automode not supported\n");
>  	}
> 
> -	INIT_DELAYED_WORK(&bq->work, bq2415x_timer_work);
>  	bq2415x_set_autotimer(bq, 1);
> 
>  	dev_info(bq->dev, "driver registered\n");

Looks like this is really problem. I sent alternative patch to mailing 
list which should fix this problem too plus allows to load 
bq2415x_charger.ko in n900 qemu.

-- 
Pali Rohár
pali.rohar@...il.com

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