linux-kernel - Re: [PATCH] phy: core: check whether ops callback function is assigned

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Date:   Tue, 27 Dec 2016 17:37:32 +0900
From:   Jaehoon Chung <jh80.chung@...sung.com>
To:     Kishon Vijay Abraham I <kishon@...com>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] phy: core: check whether ops callback function is assigned

On 12/27/2016 05:31 PM, Kishon Vijay Abraham I wrote:
> Hi,
> 
> On Thursday 22 December 2016 03:12 PM, Jaehoon Chung wrote:
>> If some ops-> callback function are not assigend, then it should do the
>> unexpect behavior.
>> To prevent the potential NULL pointer dereference, check the each
>> callback functions before doing operation.
> 
> The call backs checks are done after the mutex. Moreover even if the call backs
> are not assigned, the user can call the phy ops for doing pm_runtime.

Yes. I found this patch also is wrong. Thanks for pointing out.

Best Regards,
Jaehoon Chung

> 
> Thanks
> Kishon
> 
>>
>> Signed-off-by: Jaehoon Chung <jh80.chung@...sung.com>
>> ---
>>  drivers/phy/phy-core.c | 8 ++++----
>>  1 file changed, 4 insertions(+), 4 deletions(-)
>>
>> diff --git a/drivers/phy/phy-core.c b/drivers/phy/phy-core.c
>> index a268f4d6f3e9..e4eb4431c8a4 100644
>> --- a/drivers/phy/phy-core.c
>> +++ b/drivers/phy/phy-core.c
>> @@ -219,7 +219,7 @@ int phy_init(struct phy *phy)
>>  {
>>  	int ret;
>>  
>> -	if (!phy)
>> +	if (!phy || !phy->ops->init)
>>  		return 0;
>>  
>>  	ret = phy_pm_runtime_get_sync(phy);
>> @@ -248,7 +248,7 @@ int phy_exit(struct phy *phy)
>>  {
>>  	int ret;
>>  
>> -	if (!phy)
>> +	if (!phy || !phy->ops->exit)
>>  		return 0;
>>  
>>  	ret = phy_pm_runtime_get_sync(phy);
>> @@ -277,7 +277,7 @@ int phy_power_on(struct phy *phy)
>>  {
>>  	int ret = 0;
>>  
>> -	if (!phy)
>> +	if (!phy || !phy->ops->power_on)
>>  		goto out;
>>  
>>  	if (phy->pwr) {
>> @@ -319,7 +319,7 @@ int phy_power_off(struct phy *phy)
>>  {
>>  	int ret;
>>  
>> -	if (!phy)
>> +	if (!phy || !phy->ops->power_off)
>>  		return 0;
>>  
>>  	mutex_lock(&phy->mutex);
>>
> 
> 
>