linux-kernel - Re: [PATCH 4/9] usb: phy: am335x-control: prevent module from being unloaded when in use

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Message-ID: <20140718135012.GD24914@saruman.home>
Date:	Fri, 18 Jul 2014 08:50:13 -0500
From:	Felipe Balbi <balbi@...com>
To:	Lothar Waßmann <LW@...O-electronics.de>
CC:	Felipe Balbi <balbi@...com>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	<linux-kernel@...r.kernel.org>, <linux-usb@...r.kernel.org>,
	Ezequiel Garcia <ezequiel@...guardiasur.com.ar>,
	George Cherian <george.cherian@...com>,
	<linux-arm-kernel@...ts.infradead.org>,
	Roger Quadros <rogerq@...com>
Subject: Re: [PATCH 4/9] usb: phy: am335x-control: prevent module from being
 unloaded when in use

On Fri, Jul 18, 2014 at 11:31:25AM +0200, Lothar Waßmann wrote:
> This patch fixes the real cause of the crash that was "fixed" by
> commit 7adb5c876e9c usb: musb: Fix panic upon musb_am335x module removal
> 
> Signed-off-by: Lothar Waßmann <LW@...O-electronics.de>

what is the "real cause of the crash" ? You don't explain that here.

> ---
>  drivers/usb/phy/phy-am335x-control.c |   10 ++++++++++
>  1 file changed, 10 insertions(+)
> 
> diff --git a/drivers/usb/phy/phy-am335x-control.c b/drivers/usb/phy/phy-am335x-control.c
> index 35b6083..df3e1ba 100644
> --- a/drivers/usb/phy/phy-am335x-control.c
> +++ b/drivers/usb/phy/phy-am335x-control.c
> @@ -140,6 +140,9 @@ static int am335x_control_usb_probe(struct platform_device *pdev)
>  	const struct of_device_id *of_id;
>  	const struct phy_control *phy_ctrl;
>  
> +	if (!try_module_get(pdev->dev.parent->driver->owner))
> +		return -EPROBE_DEFER;
> +
>  	of_id = of_match_node(omap_control_usb_id_table, pdev->dev.of_node);
>  	if (!of_id)
>  		return -EINVAL;
> @@ -171,8 +174,15 @@ static int am335x_control_usb_probe(struct platform_device *pdev)
>  	return 0;
>  }
>  
> +static int am335x_control_usb_remove(struct platform_device *pdev)
> +{
> +	module_put(pdev->dev.parent->driver->owner);
> +	return 0;
> +}

I can't see how this can make any difference. Care to explain ?

-- 
balbi

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