diff mbox series

vDPA/ifcvf: assign nr_vring to the MSI vector of config_intr by default

Message ID 20220408121013.54709-1-lingshan.zhu@intel.com (mailing list archive)
State Not Applicable
Headers show
Series vDPA/ifcvf: assign nr_vring to the MSI vector of config_intr by default | expand

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Context Check Description
netdev/tree_selection success Not a local patch

Commit Message

Zhu, Lingshan April 8, 2022, 12:10 p.m. UTC 
This commit assign struct ifcvf_hw.nr_vring to the MSIX vector of the
config interrupt by default in ifcvf_request_config_irq().
ifcvf_hw.nr_vring is the most likely and the ideal case for
the device config interrupt handling, means every virtqueue has
an individual MSIX vector(0 ~ nr_vring - 1), and the config interrupt has
its own MSIX vector(number nr_vring).

This change can also make GCC W = 2 happy, silence the
"uninitialized" warning.

Signed-off-by: Zhu Lingshan <lingshan.zhu@intel.com>
Reviewed-by: Dan Carpenter <dan.carpenter@oracle.com>
---
 drivers/vdpa/ifcvf/ifcvf_main.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

Comments

Jason Wang April 13, 2022, 8:14 a.m. UTC | #1 
在 2022/4/8 下午8:10, Zhu Lingshan 写道:
> This commit assign struct ifcvf_hw.nr_vring to the MSIX vector of the
> config interrupt by default in ifcvf_request_config_irq().
> ifcvf_hw.nr_vring is the most likely and the ideal case for
> the device config interrupt handling, means every virtqueue has
> an individual MSIX vector(0 ~ nr_vring - 1), and the config interrupt has
> its own MSIX vector(number nr_vring).
>
> This change can also make GCC W = 2 happy, silence the
> "uninitialized" warning.
>
> Signed-off-by: Zhu Lingshan <lingshan.zhu@intel.com>
> Reviewed-by: Dan Carpenter <dan.carpenter@oracle.com>
> ---
>   drivers/vdpa/ifcvf/ifcvf_main.c | 8 ++++----
>   1 file changed, 4 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/vdpa/ifcvf/ifcvf_main.c b/drivers/vdpa/ifcvf/ifcvf_main.c
> index 4366320fb68d..b500fb941dab 100644
> --- a/drivers/vdpa/ifcvf/ifcvf_main.c
> +++ b/drivers/vdpa/ifcvf/ifcvf_main.c
> @@ -290,13 +290,13 @@ static int ifcvf_request_config_irq(struct ifcvf_adapter *adapter)
>   	struct ifcvf_hw *vf = &adapter->vf;
>   	int config_vector, ret;
>   
> +	/* vector 0 ~ vf->nr_vring for vqs, num vf->nr_vring vector for config interrupt */


The comment is right before this patch, but probably wrong for 
MSIX_VECTOR_DEV_SHARED.


> +	config_vector = vf->nr_vring;
> +
> +	/* re-use the vqs vector */
>   	if (vf->msix_vector_status == MSIX_VECTOR_DEV_SHARED)
>   		return 0;
>   
> -	if (vf->msix_vector_status == MSIX_VECTOR_PER_VQ_AND_CONFIG)
> -		/* vector 0 ~ vf->nr_vring for vqs, num vf->nr_vring vector for config interrupt */
> -		config_vector = vf->nr_vring;
> -
>   	if (vf->msix_vector_status ==  MSIX_VECTOR_SHARED_VQ_AND_CONFIG)
>   		/* vector 0 for vqs and 1 for config interrupt */
>   		config_vector = 1;


Actually, I prefer to use if ... else ... here.

Thanks
Zhu, Lingshan April 13, 2022, 9:16 a.m. UTC | #2 
On 4/13/2022 4:14 PM, Jason Wang wrote:
>
> 在 2022/4/8 下午8:10, Zhu Lingshan 写道:
>> This commit assign struct ifcvf_hw.nr_vring to the MSIX vector of the
>> config interrupt by default in ifcvf_request_config_irq().
>> ifcvf_hw.nr_vring is the most likely and the ideal case for
>> the device config interrupt handling, means every virtqueue has
>> an individual MSIX vector(0 ~ nr_vring - 1), and the config interrupt 
>> has
>> its own MSIX vector(number nr_vring).
>>
>> This change can also make GCC W = 2 happy, silence the
>> "uninitialized" warning.
>>
>> Signed-off-by: Zhu Lingshan <lingshan.zhu@intel.com>
>> Reviewed-by: Dan Carpenter <dan.carpenter@oracle.com>
>> ---
>>   drivers/vdpa/ifcvf/ifcvf_main.c | 8 ++++----
>>   1 file changed, 4 insertions(+), 4 deletions(-)
>>
>> diff --git a/drivers/vdpa/ifcvf/ifcvf_main.c 
>> b/drivers/vdpa/ifcvf/ifcvf_main.c
>> index 4366320fb68d..b500fb941dab 100644
>> --- a/drivers/vdpa/ifcvf/ifcvf_main.c
>> +++ b/drivers/vdpa/ifcvf/ifcvf_main.c
>> @@ -290,13 +290,13 @@ static int ifcvf_request_config_irq(struct 
>> ifcvf_adapter *adapter)
>>       struct ifcvf_hw *vf = &adapter->vf;
>>       int config_vector, ret;
>>   +    /* vector 0 ~ vf->nr_vring for vqs, num vf->nr_vring vector 
>> for config interrupt */
>
>
> The comment is right before this patch, but probably wrong for 
> MSIX_VECTOR_DEV_SHARED.
This comment is for the case when every vq and config interrupt has its 
own vector, how
about a better comment "The ideal the default case, vector 0 ~ 
vf->nr_vring for vqs, num vf->nr_vring vector for config interrupt"
>
>
>> +    config_vector = vf->nr_vring;
>> +
>> +    /* re-use the vqs vector */
>>       if (vf->msix_vector_status == MSIX_VECTOR_DEV_SHARED)
>>           return 0;
>>   -    if (vf->msix_vector_status == MSIX_VECTOR_PER_VQ_AND_CONFIG)
>> -        /* vector 0 ~ vf->nr_vring for vqs, num vf->nr_vring vector 
>> for config interrupt */
>> -        config_vector = vf->nr_vring;
>> -
>>       if (vf->msix_vector_status == MSIX_VECTOR_SHARED_VQ_AND_CONFIG)
>>           /* vector 0 for vqs and 1 for config interrupt */
>>           config_vector = 1;
>
>
> Actually, I prefer to use if ... else ... here.
IMHO, if else may lead to mistakes.

The code:
         /* The ideal the default case, vector 0 ~ vf->nr_vring for vqs, 
num vf->nr_vring vector for config interrupt */
         config_vector = vf->nr_vring;

         /* re-use the vqs vector */
         if (vf->msix_vector_status == MSIX_VECTOR_DEV_SHARED)
                 return 0;

         if (vf->msix_vector_status == MSIX_VECTOR_SHARED_VQ_AND_CONFIG)
                 /* vector 0 for vqs and 1 for config interrupt */
                 config_vector = 1;


here by default config_vector = vf->nr_vring;
If msix_vector_status == MSIX_VECTOR_DEV_SHARED, it will reuse the dev 
shared vector, means using the vector(value 0) for data-vqs.
If msix_vector_status == MSIX_VECTOR_SHARED_VQ_AND_CONFIG, it will use 
vector=1(vector 0 for data-vqs).

If we use if...else, it will be:

         /* re-use the vqs vector */
         if (vf->msix_vector_status == MSIX_VECTOR_DEV_SHARED)
                 return 0;
         else
                 config_vector = 1;

This looks like config_vector can only be 0(re-used vector for the 
data-vqs, which is 0) or 1. It shadows the ideal and default case
config_vector = vf->nr_vring

Thanks,
Zhu Lingshan

>
> Thanks
>
>
Jason Wang April 15, 2022, 5:51 a.m. UTC | #3 
On Wed, Apr 13, 2022 at 5:16 PM Zhu, Lingshan <lingshan.zhu@intel.com> wrote:
>
>
>
> On 4/13/2022 4:14 PM, Jason Wang wrote:
> >
> > 在 2022/4/8 下午8:10, Zhu Lingshan 写道:
> >> This commit assign struct ifcvf_hw.nr_vring to the MSIX vector of the
> >> config interrupt by default in ifcvf_request_config_irq().
> >> ifcvf_hw.nr_vring is the most likely and the ideal case for
> >> the device config interrupt handling, means every virtqueue has
> >> an individual MSIX vector(0 ~ nr_vring - 1), and the config interrupt
> >> has
> >> its own MSIX vector(number nr_vring).
> >>
> >> This change can also make GCC W = 2 happy, silence the
> >> "uninitialized" warning.
> >>
> >> Signed-off-by: Zhu Lingshan <lingshan.zhu@intel.com>
> >> Reviewed-by: Dan Carpenter <dan.carpenter@oracle.com>
> >> ---
> >>   drivers/vdpa/ifcvf/ifcvf_main.c | 8 ++++----
> >>   1 file changed, 4 insertions(+), 4 deletions(-)
> >>
> >> diff --git a/drivers/vdpa/ifcvf/ifcvf_main.c
> >> b/drivers/vdpa/ifcvf/ifcvf_main.c
> >> index 4366320fb68d..b500fb941dab 100644
> >> --- a/drivers/vdpa/ifcvf/ifcvf_main.c
> >> +++ b/drivers/vdpa/ifcvf/ifcvf_main.c
> >> @@ -290,13 +290,13 @@ static int ifcvf_request_config_irq(struct
> >> ifcvf_adapter *adapter)
> >>       struct ifcvf_hw *vf = &adapter->vf;
> >>       int config_vector, ret;
> >>   +    /* vector 0 ~ vf->nr_vring for vqs, num vf->nr_vring vector
> >> for config interrupt */
> >
> >
> > The comment is right before this patch, but probably wrong for
> > MSIX_VECTOR_DEV_SHARED.
> This comment is for the case when every vq and config interrupt has its
> own vector, how
> about a better comment "The ideal the default case, vector 0 ~
> vf->nr_vring for vqs, num vf->nr_vring vector for config interrupt"

Actually, I suggest to remove the comment since the code can explain itself.

> >
> >
> >> +    config_vector = vf->nr_vring;
> >> +
> >> +    /* re-use the vqs vector */
> >>       if (vf->msix_vector_status == MSIX_VECTOR_DEV_SHARED)
> >>           return 0;
> >>   -    if (vf->msix_vector_status == MSIX_VECTOR_PER_VQ_AND_CONFIG)
> >> -        /* vector 0 ~ vf->nr_vring for vqs, num vf->nr_vring vector
> >> for config interrupt */
> >> -        config_vector = vf->nr_vring;
> >> -
> >>       if (vf->msix_vector_status == MSIX_VECTOR_SHARED_VQ_AND_CONFIG)
> >>           /* vector 0 for vqs and 1 for config interrupt */
> >>           config_vector = 1;
> >
> >
> > Actually, I prefer to use if ... else ... here.
> IMHO, if else may lead to mistakes.
>
> The code:
>          /* The ideal the default case, vector 0 ~ vf->nr_vring for vqs,
> num vf->nr_vring vector for config interrupt */
>          config_vector = vf->nr_vring;
>
>          /* re-use the vqs vector */
>          if (vf->msix_vector_status == MSIX_VECTOR_DEV_SHARED)
>                  return 0;
>
>          if (vf->msix_vector_status == MSIX_VECTOR_SHARED_VQ_AND_CONFIG)
>                  /* vector 0 for vqs and 1 for config interrupt */
>                  config_vector = 1;
>
>
> here by default config_vector = vf->nr_vring;
> If msix_vector_status == MSIX_VECTOR_DEV_SHARED, it will reuse the dev
> shared vector, means using the vector(value 0) for data-vqs.
> If msix_vector_status == MSIX_VECTOR_SHARED_VQ_AND_CONFIG, it will use
> vector=1(vector 0 for data-vqs).
>
> If we use if...else, it will be:
>
>          /* re-use the vqs vector */
>          if (vf->msix_vector_status == MSIX_VECTOR_DEV_SHARED)
>                  return 0;
>          else
>                  config_vector = 1;
>
> This looks like config_vector can only be 0(re-used vector for the
> data-vqs, which is 0) or 1. It shadows the ideal and default case
> config_vector = vf->nr_vring

I meant something like

if (DEV_SHARED)
    return 0;
else if  (SHARED_VQ_AND_CONFIG)
    config_vector = 1
else if (PER_VQ_AND_CONFIG)
    config_vector = vf->nr_vring
else
    return -EINVAL;

or using a switch here.

(We get the warning because there's no way for the checker to know
that msix_vector_status must be DEV_SHARED, SHARED_VQ_AND_CONFIG and
PER_VQ_AND_CONFIG).

Thanks

>
> Thanks,
> Zhu Lingshan
>
> >
> > Thanks
> >
> >
>
diff mbox series

Patch

diff --git a/drivers/vdpa/ifcvf/ifcvf_main.c b/drivers/vdpa/ifcvf/ifcvf_main.c
index 4366320fb68d..b500fb941dab 100644
--- a/drivers/vdpa/ifcvf/ifcvf_main.c
+++ b/drivers/vdpa/ifcvf/ifcvf_main.c
@@ -290,13 +290,13 @@  static int ifcvf_request_config_irq(struct ifcvf_adapter *adapter)
 	struct ifcvf_hw *vf = &adapter->vf;
 	int config_vector, ret;
 
+	/* vector 0 ~ vf->nr_vring for vqs, num vf->nr_vring vector for config interrupt */
+	config_vector = vf->nr_vring;
+
+	/* re-use the vqs vector */
 	if (vf->msix_vector_status == MSIX_VECTOR_DEV_SHARED)
 		return 0;
 
-	if (vf->msix_vector_status == MSIX_VECTOR_PER_VQ_AND_CONFIG)
-		/* vector 0 ~ vf->nr_vring for vqs, num vf->nr_vring vector for config interrupt */
-		config_vector = vf->nr_vring;
-
 	if (vf->msix_vector_status ==  MSIX_VECTOR_SHARED_VQ_AND_CONFIG)
 		/* vector 0 for vqs and 1 for config interrupt */
 		config_vector = 1;