[v3,2/3] gianfar: Delete unnecessary variable initialisations in gfar_ethflow_to_filer_table()

From: Markus Elfring <elfring@users.sourceforge.net>
Date: Fri, 15 Jan 2016 10:40:24 +0100

Omit explicit initialisation at the beginning for four local variables
which are redefined before their first use.

Signed-off-by: Markus Elfring <elfring@users.sourceforge.net>
---
 drivers/net/ethernet/freescale/gianfar_ethtool.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

On Fri, Jan 15, 2016 at 11:12:42AM +0100, SF Markus Elfring wrote:
> From: Markus Elfring <elfring@users.sourceforge.net>
> Date: Fri, 15 Jan 2016 10:40:24 +0100
> 
> Omit explicit initialisation at the beginning for four local variables
> which are redefined before their first use.
> 
> Signed-off-by: Markus Elfring <elfring@users.sourceforge.net>
> ---
>  drivers/net/ethernet/freescale/gianfar_ethtool.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/net/ethernet/freescale/gianfar_ethtool.c b/drivers/net/ethernet/freescale/gianfar_ethtool.c
> index 825b051..8302f7d 100644
> --- a/drivers/net/ethernet/freescale/gianfar_ethtool.c
> +++ b/drivers/net/ethernet/freescale/gianfar_ethtool.c
> @@ -768,12 +768,12 @@ static void ethflow_to_filer_rules (struct gfar_private *priv, u64 ethflow)
>  static int gfar_ethflow_to_filer_table(struct gfar_private *priv, u64 ethflow,
>  				       u64 class)
>  {
> -	unsigned int last_rule_idx = priv->cur_filer_idx;
> +	unsigned int last_rule_idx;

This is a write only variable.  We can just remove it.

regards,
dan carpenter

>> +++ b/drivers/net/ethernet/freescale/gianfar_ethtool.c
>> @@ -768,12 +768,12 @@ static void ethflow_to_filer_rules (struct gfar_private *priv, u64 ethflow)
>>  static int gfar_ethflow_to_filer_table(struct gfar_private *priv, u64 ethflow,
>>  				       u64 class)
>>  {
>> -	unsigned int last_rule_idx = priv->cur_filer_idx;
>> +	unsigned int last_rule_idx;
> 
> This is a write only variable.  We can just remove it.

Can a static source code analysis tool like the software "http://smatch.sourceforge.net/"
detect that such a variable is not read by this function implementation so far?
https://git.kernel.org/cgit/linux/kernel/git/next/linux-next.git/tree/drivers/net/ethernet/freescale/gianfar_ethtool.c?id=b75ec3af27bf011a760e2f44eb25a99b6fbb0fb3#n850

Does this place indicate an unwanted value assignment as a leftover,
or are there any other actions missing?

Regards,
Markus

On Fri, Jan 15, 2016 at 12:34:33PM +0100, SF Markus Elfring wrote:
> >> +++ b/drivers/net/ethernet/freescale/gianfar_ethtool.c
> >> @@ -768,12 +768,12 @@ static void ethflow_to_filer_rules (struct gfar_private *priv, u64 ethflow)
> >>  static int gfar_ethflow_to_filer_table(struct gfar_private *priv, u64 ethflow,
> >>  				       u64 class)
> >>  {
> >> -	unsigned int last_rule_idx = priv->cur_filer_idx;
> >> +	unsigned int last_rule_idx;
> > 
> > This is a write only variable.  We can just remove it.
> 
> Can a static source code analysis tool like the software "http://smatch.sourceforge.net/"
> detect that such a variable is not read by this function implementation so far?

Yeah.  That's a good idea.  I will do that.

> https://git.kernel.org/cgit/linux/kernel/git/next/linux-next.git/tree/drivers/net/ethernet/freescale/gianfar_ethtool.c?id=b75ec3af27bf011a760e2f44eb25a99b6fbb0fb3#n850
> 
> Does this place indicate an unwanted value assignment as a leftover,
> or are there any other actions missing?

I think it's just an extra variable and you can just delete it.

regards,
dan carpenter

From: SF Markus Elfring <elfring@users.sourceforge.net>
Date: Fri, 15 Jan 2016 12:34:33 +0100

>>> +++ b/drivers/net/ethernet/freescale/gianfar_ethtool.c
>>> @@ -768,12 +768,12 @@ static void ethflow_to_filer_rules (struct gfar_private *priv, u64 ethflow)
>>>  static int gfar_ethflow_to_filer_table(struct gfar_private *priv, u64 ethflow,
>>>  				       u64 class)
>>>  {
>>> -	unsigned int last_rule_idx = priv->cur_filer_idx;
>>> +	unsigned int last_rule_idx;
>> 
>> This is a write only variable.  We can just remove it.
> 
> Can a static source code analysis tool like the software "http://smatch.sourceforge.net/"
> detect that such a variable is not read by this function implementation so far?

No, but a human can.

And a human should fully analyze any change he writes based upon static
analysis tool results.

I am going to be honest, and say that I am completely ignoring most of
your static checker patches.  You don't put enough care and consideration
into them, and I really don't have time to waste on looking at something
like that.

>>> This is a write only variable.  We can just remove it.
>>
>> Can a static source code analysis tool like the software "http://smatch.sourceforge.net/"
>> detect that such a variable is not read by this function implementation so far?
> 
> No,

I imagine that there are a few tools available which can point such update candidates out.
There are various software development challenges to consider.


> but a human can.

Some software developers and source code reviewers are struggling with mentioned
implementation details as usual. Do they also wonder how the discussed variable assignment
was left over in a specific function?


> I am going to be honest, and say that I am completely ignoring most of
> your static checker patches.

I am curious if you would reconsider the affected source code places once more
when you will be notified about related issues by other tools or persons.


> You don't put enough care and consideration into them,

Would you like to explain this impression a bit more?


> and I really don't have time to waste on looking at something like that.

Thanks for your feedback.

Various open issues are competing for our attention as usual.

Regards,
Markus