[PATCH 1/9] usb: otg: use try_module_get in all usb_get_phy functions and add missing module_put

[mkl@pengutronix.de (Marc Kleine-Budde)]

On 02/04/2013 02:59 PM, Roger Quadros wrote:
> On 02/04/2013 03:24 PM, Sascha Hauer wrote:
>> From: Marc Kleine-Budde <mkl@pengutronix.de>
>>
>> In patch "5d3c28b usb: otg: add device tree support to otg library"
>> devm_usb_get_phy_by_phandle() was added. It uses try_module_get() to lock the
>> phy driver in memory. The corresponding module_put() is missing in that patch.
>>
>> This patch adds try_module_get() to usb_get_phy() and usb_get_phy_dev().
>> Further the missing module_put() is added to usb_put_phy().
>>
>> Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
>> Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
>> ---
>>  drivers/usb/otg/otg.c |   10 +++++++---
>>  1 file changed, 7 insertions(+), 3 deletions(-)
>>
>> diff --git a/drivers/usb/otg/otg.c b/drivers/usb/otg/otg.c
>> index e181439..2bd03d2 100644
>> --- a/drivers/usb/otg/otg.c
>> +++ b/drivers/usb/otg/otg.c
>> @@ -130,7 +130,7 @@ struct usb_phy *usb_get_phy(enum usb_phy_type type)
>>  	spin_lock_irqsave(&phy_lock, flags);
>>  
>>  	phy = __usb_find_phy(&phy_list, type);
>> -	if (IS_ERR(phy)) {
>> +	if (IS_ERR(phy) || !try_module_get(phy->dev->driver->owner)) {
>>  		pr_err("unable to find transceiver of type %s\n",
>>  			usb_phy_type_string(type));
>>  		goto err0;
> 
> There are 2 problems with this.
> 
> - If phy was found but try_module_get failed you are not returning error code.

Correct - but....

> - If phy was found and try_module_get fails we would want to use deferred probing,
> since this case is possible if the phy module is not yet loaded and alive but can be in
> the future.

...this should not happen, as the phy list is protected by the
spin_lock. If a phy driver module has added a the phy to the
infrastructure, but has been rmmod'ed without removing the phy. The phy
driver is broken anyway.

Marc

-- 
Pengutronix e.K.                  | Marc Kleine-Budde           |
Industrial Linux Solutions        | Phone: +49-231-2826-924     |
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