net: macb: Remove redundant assignment to w0 and queue

Variable w0 and queue is set to zero and bp->queues but these
values is not used as it is overwritten later on, hence
redundant assignment  can be removed.

Cleans up the following clang-analyzer warning:

drivers/net/ethernet/cadence/macb_main.c:4919:21: warning: Value stored
to 'queue' during its initialization is never read
[clang-analyzer-deadcode.DeadStores].

drivers/net/ethernet/cadence/macb_main.c:4832:21: warning: Value stored
to 'queue' during its initialization is never read
[clang-analyzer-deadcode.DeadStores].

drivers/net/ethernet/cadence/macb_main.c:3265:3: warning: Value stored
to 'w0' is never read [clang-analyzer-deadcode.DeadStores].

drivers/net/ethernet/cadence/macb_main.c:3251:3: warning: Value stored
to 'w0' is never read [clang-analyzer-deadcode.DeadStores].

Reported-by: Abaci Robot <abaci@linux.alibaba.com>
Signed-off-by: Jiapeng Chong <jiapeng.chong@linux.alibaba.com>
---
 drivers/net/ethernet/cadence/macb_main.c | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

On Wed, 28 Apr 2021 18:03:08 +0800 Jiapeng Chong wrote:
> diff --git a/drivers/net/ethernet/cadence/macb_main.c b/drivers/net/ethernet/cadence/macb_main.c
> index 0f6a6cb..5f1dbc2 100644
> --- a/drivers/net/ethernet/cadence/macb_main.c
> +++ b/drivers/net/ethernet/cadence/macb_main.c
> @@ -3248,7 +3248,6 @@ static void gem_prog_cmp_regs(struct macb *bp, struct ethtool_rx_flow_spec *fs)
>  	/* ignore field if any masking set */
>  	if (tp4sp_m->ip4src == 0xFFFFFFFF) {
>  		/* 1st compare reg - IP source address */
> -		w0 = 0;
>  		w1 = 0;
>  		w0 = tp4sp_v->ip4src;
>  		w1 = GEM_BFINS(T2DISMSK, 1, w1); /* 32-bit compare */
> @@ -3262,7 +3261,6 @@ static void gem_prog_cmp_regs(struct macb *bp, struct ethtool_rx_flow_spec *fs)
>  	/* ignore field if any masking set */
>  	if (tp4sp_m->ip4dst == 0xFFFFFFFF) {
>  		/* 2nd compare reg - IP destination address */
> -		w0 = 0;
>  		w1 = 0;
>  		w0 = tp4sp_v->ip4dst;
>  		w1 = GEM_BFINS(T2DISMSK, 1, w1); /* 32-bit compare */

Looks like this was written like that on purpose.

> @@ -4829,7 +4827,7 @@ static int __maybe_unused macb_suspend(struct device *dev)
>  {
>  	struct net_device *netdev = dev_get_drvdata(dev);
>  	struct macb *bp = netdev_priv(netdev);
> -	struct macb_queue *queue = bp->queues;
> +	struct macb_queue *queue;
>  	unsigned long flags;
>  	unsigned int q;
>  	int err;
> @@ -4916,7 +4914,7 @@ static int __maybe_unused macb_resume(struct device *dev)
>  {
>  	struct net_device *netdev = dev_get_drvdata(dev);
>  	struct macb *bp = netdev_priv(netdev);
> -	struct macb_queue *queue = bp->queues;
> +	struct macb_queue *queue;
>  	unsigned long flags;
>  	unsigned int q;
>  	int err;

This chunk looks good!

Would you mind splitting the patch into two (1 - w0 assignments, and 
2 - queue assignments) and reposting? We can merge the latter, the
former is up to the driver maintainer to decide.

On 28/04/2021 at 21:21, Jakub Kicinski wrote:
> EXTERNAL EMAIL: Do not click links or open attachments unless you know the content is safe

> 

> On Wed, 28 Apr 2021 18:03:08 +0800 Jiapeng Chong wrote:

>> diff --git a/drivers/net/ethernet/cadence/macb_main.c b/drivers/net/ethernet/cadence/macb_main.c

>> index 0f6a6cb..5f1dbc2 100644

>> --- a/drivers/net/ethernet/cadence/macb_main.c

>> +++ b/drivers/net/ethernet/cadence/macb_main.c

>> @@ -3248,7 +3248,6 @@ static void gem_prog_cmp_regs(struct macb *bp, struct ethtool_rx_flow_spec *fs)

>>        /* ignore field if any masking set */

>>        if (tp4sp_m->ip4src == 0xFFFFFFFF) {

>>                /* 1st compare reg - IP source address */

>> -             w0 = 0;

>>                w1 = 0;

>>                w0 = tp4sp_v->ip4src;

>>                w1 = GEM_BFINS(T2DISMSK, 1, w1); /* 32-bit compare */

>> @@ -3262,7 +3261,6 @@ static void gem_prog_cmp_regs(struct macb *bp, struct ethtool_rx_flow_spec *fs)

>>        /* ignore field if any masking set */

>>        if (tp4sp_m->ip4dst == 0xFFFFFFFF) {

>>                /* 2nd compare reg - IP destination address */

>> -             w0 = 0;

>>                w1 = 0;

>>                w0 = tp4sp_v->ip4dst;

>>                w1 = GEM_BFINS(T2DISMSK, 1, w1); /* 32-bit compare */

> 

> Looks like this was written like that on purpose.

> 

>> @@ -4829,7 +4827,7 @@ static int __maybe_unused macb_suspend(struct device *dev)

>>   {

>>        struct net_device *netdev = dev_get_drvdata(dev);

>>        struct macb *bp = netdev_priv(netdev);

>> -     struct macb_queue *queue = bp->queues;

>> +     struct macb_queue *queue;

>>        unsigned long flags;

>>        unsigned int q;

>>        int err;

>> @@ -4916,7 +4914,7 @@ static int __maybe_unused macb_resume(struct device *dev)

>>   {

>>        struct net_device *netdev = dev_get_drvdata(dev);

>>        struct macb *bp = netdev_priv(netdev);

>> -     struct macb_queue *queue = bp->queues;

>> +     struct macb_queue *queue;

>>        unsigned long flags;

>>        unsigned int q;

>>        int err;

> 

> This chunk looks good!

> 

> Would you mind splitting the patch into two (1 - w0 assignments, and

> 2 - queue assignments) and reposting? We can merge the latter, the

> former is up to the driver maintainer to decide.


Good move Jakub, thanks for having suggested this as we are highlighting 
a bug!

Best regards,
   Nicolas

-- 
Nicolas Ferre