[PATCH][next] mlxsw: spectrum_router: remove redundant initialization of variable force

[PATCH][next] mlxsw: spectrum_router: remove redundant initialization of variable force

[Colin King]

From: Colin Ian King <colin.king@canonical.com>

The variable force is being initialized with a value that is
never read and it is being updated later with a new value. The
initialization is redundant and can be removed.

Addresses-Coverity: ("Unused value")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
---
 drivers/net/ethernet/mellanox/mlxsw/spectrum_router.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/mellanox/mlxsw/spectrum_router.c b/drivers/net/ethernet/mellanox/mlxsw/spectrum_router.c
index 6ccaa194733b..ff240e3c29f7 100644
--- a/drivers/net/ethernet/mellanox/mlxsw/spectrum_router.c
+++ b/drivers/net/ethernet/mellanox/mlxsw/spectrum_router.c
@@ -5059,7 +5059,7 @@ mlxsw_sp_nexthop_obj_bucket_adj_update(struct mlxsw_sp *mlxsw_sp,
 {
 	u16 bucket_index = info->nh_res_bucket->bucket_index;
 	struct netlink_ext_ack *extack = info->extack;
-	bool force = info->nh_res_bucket->force;
+	bool force;
 	char ratr_pl_new[MLXSW_REG_RATR_LEN];
 	char ratr_pl[MLXSW_REG_RATR_LEN];
 	u32 adj_index;
-- 
2.30.2

Re: [PATCH][next] mlxsw: spectrum_router: remove redundant initialization of variable force

[Dan Carpenter]

On Sat, Mar 27, 2021 at 10:33:34PM +0000, Colin King wrote:
> From: Colin Ian King <colin.king@canonical.com>
> 
> The variable force is being initialized with a value that is
> never read and it is being updated later with a new value. The
> initialization is redundant and can be removed.
> 
> Addresses-Coverity: ("Unused value")
> Signed-off-by: Colin Ian King <colin.king@canonical.com>
> ---
>  drivers/net/ethernet/mellanox/mlxsw/spectrum_router.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/net/ethernet/mellanox/mlxsw/spectrum_router.c b/drivers/net/ethernet/mellanox/mlxsw/spectrum_router.c
> index 6ccaa194733b..ff240e3c29f7 100644
> --- a/drivers/net/ethernet/mellanox/mlxsw/spectrum_router.c
> +++ b/drivers/net/ethernet/mellanox/mlxsw/spectrum_router.c
> @@ -5059,7 +5059,7 @@ mlxsw_sp_nexthop_obj_bucket_adj_update(struct mlxsw_sp *mlxsw_sp,
>  {
>  	u16 bucket_index = info->nh_res_bucket->bucket_index;
>  	struct netlink_ext_ack *extack = info->extack;
> -	bool force = info->nh_res_bucket->force;
> +	bool force;
>  	char ratr_pl_new[MLXSW_REG_RATR_LEN];
>  	char ratr_pl[MLXSW_REG_RATR_LEN];
>  	u32 adj_index;

Reverse Christmas tree.

regards,
dan carpenter

Re: [PATCH][next] mlxsw: spectrum_router: remove redundant initialization of variable force

[Joe Perches]

On Mon, 2021-03-29 at 09:04 +0300, Dan Carpenter wrote:
> On Sat, Mar 27, 2021 at 10:33:34PM +0000, Colin King wrote:
> > From: Colin Ian King <colin.king@canonical.com>
> > 
> > The variable force is being initialized with a value that is
> > never read and it is being updated later with a new value. The
> > initialization is redundant and can be removed.
> > 
> > Addresses-Coverity: ("Unused value")
> > Signed-off-by: Colin Ian King <colin.king@canonical.com>
> > ---
> >  drivers/net/ethernet/mellanox/mlxsw/spectrum_router.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> > 
> > diff --git a/drivers/net/ethernet/mellanox/mlxsw/spectrum_router.c b/drivers/net/ethernet/mellanox/mlxsw/spectrum_router.c
> > index 6ccaa194733b..ff240e3c29f7 100644
> > --- a/drivers/net/ethernet/mellanox/mlxsw/spectrum_router.c
> > +++ b/drivers/net/ethernet/mellanox/mlxsw/spectrum_router.c
> > @@ -5059,7 +5059,7 @@ mlxsw_sp_nexthop_obj_bucket_adj_update(struct mlxsw_sp *mlxsw_sp,
> >  {
> >  	u16 bucket_index = info->nh_res_bucket->bucket_index;
> >  	struct netlink_ext_ack *extack = info->extack;
> > -	bool force = info->nh_res_bucket->force;
> > +	bool force;
> >  	char ratr_pl_new[MLXSW_REG_RATR_LEN];
> >  	char ratr_pl[MLXSW_REG_RATR_LEN];
> >  	u32 adj_index;
> 
> Reverse Christmas tree.

Is still terrible style.

Re: [PATCH][next] mlxsw: spectrum_router: remove redundant initialization of variable force

[Ido Schimmel]

On Sat, Mar 27, 2021 at 10:33:34PM +0000, Colin King wrote:
> From: Colin Ian King <colin.king@canonical.com>
> 
> The variable force is being initialized with a value that is
> never read and it is being updated later with a new value. The
> initialization is redundant and can be removed.
> 
> Addresses-Coverity: ("Unused value")
> Signed-off-by: Colin Ian King <colin.king@canonical.com>
> ---
>  drivers/net/ethernet/mellanox/mlxsw/spectrum_router.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/net/ethernet/mellanox/mlxsw/spectrum_router.c b/drivers/net/ethernet/mellanox/mlxsw/spectrum_router.c
> index 6ccaa194733b..ff240e3c29f7 100644
> --- a/drivers/net/ethernet/mellanox/mlxsw/spectrum_router.c
> +++ b/drivers/net/ethernet/mellanox/mlxsw/spectrum_router.c
> @@ -5059,7 +5059,7 @@ mlxsw_sp_nexthop_obj_bucket_adj_update(struct mlxsw_sp *mlxsw_sp,
>  {
>  	u16 bucket_index = info->nh_res_bucket->bucket_index;
>  	struct netlink_ext_ack *extack = info->extack;
> -	bool force = info->nh_res_bucket->force;
> +	bool force;

Actually, there is a bug to be fixed here:

```
diff --git a/drivers/net/ethernet/mellanox/mlxsw/spectrum_router.c b/drivers/net/ethernet/mellanox/mlxsw/spectrum_router.c
index 6ccaa194733b..41259c0004d1 100644
--- a/drivers/net/ethernet/mellanox/mlxsw/spectrum_router.c
+++ b/drivers/net/ethernet/mellanox/mlxsw/spectrum_router.c
@@ -5068,8 +5068,9 @@ mlxsw_sp_nexthop_obj_bucket_adj_update(struct mlxsw_sp *mlxsw_sp,
        /* No point in trying an atomic replacement if the idle timer interval
         * is smaller than the interval in which we query and clear activity.
         */
-       force = info->nh_res_bucket->idle_timer_ms <
-               MLXSW_SP_NH_GRP_ACTIVITY_UPDATE_INTERVAL;
+       if (!force && info->nh_res_bucket->idle_timer_ms <
+           MLXSW_SP_NH_GRP_ACTIVITY_UPDATE_INTERVAL)
+               force = true;
 
        adj_index = nh->nhgi->adj_index + bucket_index;
        err = mlxsw_sp_nexthop_update(mlxsw_sp, adj_index, nh, force, ratr_pl);
```

We should only fallback to a non-atomic replacement when the current
replacement is atomic and the idle timer is too short.

We currently ignore the value of 'force'. This means that a non-atomic
replacement ('force' is true) can be made atomic if idle timer is larger
than 1 second.

Colin, do you mind if I submit it formally as a fix later this week? I
want to run it through our usual process. Will mention you in
Reported-by, obviously.

>  	char ratr_pl_new[MLXSW_REG_RATR_LEN];
>  	char ratr_pl[MLXSW_REG_RATR_LEN];
>  	u32 adj_index;
> -- 
> 2.30.2
> 

Re: [PATCH][next] mlxsw: spectrum_router: remove redundant initialization of variable force

[Colin Ian King]

On 29/03/2021 08:13, Ido Schimmel wrote:
> On Sat, Mar 27, 2021 at 10:33:34PM +0000, Colin King wrote:
>> From: Colin Ian King <colin.king@canonical.com>
>>
>> The variable force is being initialized with a value that is
>> never read and it is being updated later with a new value. The
>> initialization is redundant and can be removed.
>>
>> Addresses-Coverity: ("Unused value")
>> Signed-off-by: Colin Ian King <colin.king@canonical.com>
>> ---
>>  drivers/net/ethernet/mellanox/mlxsw/spectrum_router.c | 2 +-
>>  1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/drivers/net/ethernet/mellanox/mlxsw/spectrum_router.c b/drivers/net/ethernet/mellanox/mlxsw/spectrum_router.c
>> index 6ccaa194733b..ff240e3c29f7 100644
>> --- a/drivers/net/ethernet/mellanox/mlxsw/spectrum_router.c
>> +++ b/drivers/net/ethernet/mellanox/mlxsw/spectrum_router.c
>> @@ -5059,7 +5059,7 @@ mlxsw_sp_nexthop_obj_bucket_adj_update(struct mlxsw_sp *mlxsw_sp,
>>  {
>>  	u16 bucket_index = info->nh_res_bucket->bucket_index;
>>  	struct netlink_ext_ack *extack = info->extack;
>> -	bool force = info->nh_res_bucket->force;
>> +	bool force;
> 
> Actually, there is a bug to be fixed here:
> 
> ```
> diff --git a/drivers/net/ethernet/mellanox/mlxsw/spectrum_router.c b/drivers/net/ethernet/mellanox/mlxsw/spectrum_router.c
> index 6ccaa194733b..41259c0004d1 100644
> --- a/drivers/net/ethernet/mellanox/mlxsw/spectrum_router.c
> +++ b/drivers/net/ethernet/mellanox/mlxsw/spectrum_router.c
> @@ -5068,8 +5068,9 @@ mlxsw_sp_nexthop_obj_bucket_adj_update(struct mlxsw_sp *mlxsw_sp,
>         /* No point in trying an atomic replacement if the idle timer interval
>          * is smaller than the interval in which we query and clear activity.
>          */
> -       force = info->nh_res_bucket->idle_timer_ms <
> -               MLXSW_SP_NH_GRP_ACTIVITY_UPDATE_INTERVAL;
> +       if (!force && info->nh_res_bucket->idle_timer_ms <
> +           MLXSW_SP_NH_GRP_ACTIVITY_UPDATE_INTERVAL)
> +               force = true;
>  
>         adj_index = nh->nhgi->adj_index + bucket_index;
>         err = mlxsw_sp_nexthop_update(mlxsw_sp, adj_index, nh, force, ratr_pl);
> ```
> 
> We should only fallback to a non-atomic replacement when the current
> replacement is atomic and the idle timer is too short.
> 
> We currently ignore the value of 'force'. This means that a non-atomic
> replacement ('force' is true) can be made atomic if idle timer is larger
> than 1 second.
> 
> Colin, do you mind if I submit it formally as a fix later this week? I
> want to run it through our usual process. Will mention you in
> Reported-by, obviously.

Sure. Good idea.

> 
>>  	char ratr_pl_new[MLXSW_REG_RATR_LEN];
>>  	char ratr_pl[MLXSW_REG_RATR_LEN];
>>  	u32 adj_index;
>> -- 
>> 2.30.2
>>