2024-02-15 16:12:34

by Asbjørn Sloth Tønnesen

[permalink] [raw]
Subject: [PATCH net-next 1/3] net: sched: cls_api: add skip_sw counter

Maintain a count of skip_sw filters.

This counter is protected by the cb_lock, and is updated
at the same time as offloadcnt.

Signed-off-by: Asbjørn Sloth Tønnesen <[email protected]>
---
include/net/sch_generic.h | 1 +
net/sched/cls_api.c | 4 ++++
2 files changed, 5 insertions(+)

diff --git a/include/net/sch_generic.h b/include/net/sch_generic.h
index 934fdb977551..46a63d1818a0 100644
--- a/include/net/sch_generic.h
+++ b/include/net/sch_generic.h
@@ -476,6 +476,7 @@ struct tcf_block {
struct flow_block flow_block;
struct list_head owner_list;
bool keep_dst;
+ atomic_t skipswcnt; /* Number of skip_sw filters */
atomic_t offloadcnt; /* Number of oddloaded filters */
unsigned int nooffloaddevcnt; /* Number of devs unable to do offload */
unsigned int lockeddevcnt; /* Number of devs that require rtnl lock. */
diff --git a/net/sched/cls_api.c b/net/sched/cls_api.c
index ca5676b2668e..397c3d29659c 100644
--- a/net/sched/cls_api.c
+++ b/net/sched/cls_api.c
@@ -3483,6 +3483,8 @@ static void tcf_block_offload_inc(struct tcf_block *block, u32 *flags)
if (*flags & TCA_CLS_FLAGS_IN_HW)
return;
*flags |= TCA_CLS_FLAGS_IN_HW;
+ if (tc_skip_sw(*flags))
+ atomic_inc(&block->skipswcnt);
atomic_inc(&block->offloadcnt);
}

@@ -3491,6 +3493,8 @@ static void tcf_block_offload_dec(struct tcf_block *block, u32 *flags)
if (!(*flags & TCA_CLS_FLAGS_IN_HW))
return;
*flags &= ~TCA_CLS_FLAGS_IN_HW;
+ if (tc_skip_sw(*flags))
+ atomic_dec(&block->skipswcnt);
atomic_dec(&block->offloadcnt);
}

--
2.43.0



2024-02-15 23:41:29

by Asbjørn Sloth Tønnesen

[permalink] [raw]
Subject: Re: [PATCH net-next 1/3] net: sched: cls_api: add skip_sw counter

Hi Jamal,

Thank you for the review.

On 2/15/24 17:39, Jamal Hadi Salim wrote:
> +Cc Vlad and Marcelo..
>
> On Thu, Feb 15, 2024 at 11:06 AM Asbjørn Sloth Tønnesen <[email protected]> wrote:
>>
>> Maintain a count of skip_sw filters.
>>
>> This counter is protected by the cb_lock, and is updated
>> at the same time as offloadcnt.
>>
>> Signed-off-by: Asbjørn Sloth Tønnesen <[email protected]>
>> ---
>> include/net/sch_generic.h | 1 +
>> net/sched/cls_api.c | 4 ++++
>> 2 files changed, 5 insertions(+)
>>
>> diff --git a/include/net/sch_generic.h b/include/net/sch_generic.h
>> index 934fdb977551..46a63d1818a0 100644
>> --- a/include/net/sch_generic.h
>> +++ b/include/net/sch_generic.h
>> @@ -476,6 +476,7 @@ struct tcf_block {
>> struct flow_block flow_block;
>> struct list_head owner_list;
>> bool keep_dst;
>> + atomic_t skipswcnt; /* Number of skip_sw filters */
>> atomic_t offloadcnt; /* Number of oddloaded filters */
>
> For your use case is skipswcnt ever going to be any different than offloadcnt?

No, we only use skip_sw filters, since we only use TC as a control path to
install skip_sw rules into hardware.

AFAICT offloadcnt is the sum of skip_sw filters, and filters with no flags which
have implicitly been offloaded.

The reason that I didn't just use offloadcnt, is that I'm not sure if it is
acceptable to treat implicitly offloaded rules without skip_sw, as if they were
explicitly skip_sw. It sounds reasonable, given that the filters without skip_* flags
shouldn't really care.

I tried to only trigger the TC bypass, in the cases that I was absolutely sure would
be safe as a first step.


>
> cheers,
> jamal
>
>> unsigned int nooffloaddevcnt; /* Number of devs unable to do offload */
>> unsigned int lockeddevcnt; /* Number of devs that require rtnl lock. */
>> diff --git a/net/sched/cls_api.c b/net/sched/cls_api.c
>> index ca5676b2668e..397c3d29659c 100644
>> --- a/net/sched/cls_api.c
>> +++ b/net/sched/cls_api.c
>> @@ -3483,6 +3483,8 @@ static void tcf_block_offload_inc(struct tcf_block *block, u32 *flags)
>> if (*flags & TCA_CLS_FLAGS_IN_HW)
>> return;
>> *flags |= TCA_CLS_FLAGS_IN_HW;
>> + if (tc_skip_sw(*flags))
>> + atomic_inc(&block->skipswcnt);
>> atomic_inc(&block->offloadcnt);
>> }
>>
>> @@ -3491,6 +3493,8 @@ static void tcf_block_offload_dec(struct tcf_block *block, u32 *flags)
>> if (!(*flags & TCA_CLS_FLAGS_IN_HW))
>> return;
>> *flags &= ~TCA_CLS_FLAGS_IN_HW;
>> + if (tc_skip_sw(*flags))
>> + atomic_dec(&block->skipswcnt);
>> atomic_dec(&block->offloadcnt);
>> }
>>
>> --
>> 2.43.0
>>

--
Best regards
Asbjørn Sloth Tønnesen
Network Engineer
Fiberby - AS42541

2024-02-16 08:44:31

by Vlad Buslov

[permalink] [raw]
Subject: Re: [PATCH net-next 1/3] net: sched: cls_api: add skip_sw counter

On Thu 15 Feb 2024 at 23:34, Asbjørn Sloth Tønnesen <[email protected]> wrote:
> Hi Jamal,
>
> Thank you for the review.
>
> On 2/15/24 17:39, Jamal Hadi Salim wrote:
>> +Cc Vlad and Marcelo..
>> On Thu, Feb 15, 2024 at 11:06 AM Asbjørn Sloth Tønnesen <[email protected]>
>> wrote:
>>>
>>> Maintain a count of skip_sw filters.
>>>
>>> This counter is protected by the cb_lock, and is updated
>>> at the same time as offloadcnt.
>>>
>>> Signed-off-by: Asbjørn Sloth Tønnesen <[email protected]>
>>> ---
>>> include/net/sch_generic.h | 1 +
>>> net/sched/cls_api.c | 4 ++++
>>> 2 files changed, 5 insertions(+)
>>>
>>> diff --git a/include/net/sch_generic.h b/include/net/sch_generic.h
>>> index 934fdb977551..46a63d1818a0 100644
>>> --- a/include/net/sch_generic.h
>>> +++ b/include/net/sch_generic.h
>>> @@ -476,6 +476,7 @@ struct tcf_block {
>>> struct flow_block flow_block;
>>> struct list_head owner_list;
>>> bool keep_dst;
>>> + atomic_t skipswcnt; /* Number of skip_sw filters */
>>> atomic_t offloadcnt; /* Number of oddloaded filters */
>> For your use case is skipswcnt ever going to be any different than offloadcnt?
>
> No, we only use skip_sw filters, since we only use TC as a control path to
> install skip_sw rules into hardware.
>
> AFAICT offloadcnt is the sum of skip_sw filters, and filters with no flags which
> have implicitly been offloaded.
>
> The reason that I didn't just use offloadcnt, is that I'm not sure if it is
> acceptable to treat implicitly offloaded rules without skip_sw, as if they were
> explicitly skip_sw. It sounds reasonable, given that the filters without skip_* flags
> shouldn't really care.

It is not acceptable since there are valid use-cases where packets need
to match sw filters that are supposedly also in-hw. For example, filters
with tunnel_key set action during neighbor update event.

>
> I tried to only trigger the TC bypass, in the cases that I was absolutely sure would
> be safe as a first step.
>
>
>> cheers,
>> jamal
>>
>>> unsigned int nooffloaddevcnt; /* Number of devs unable to do offload */
>>> unsigned int lockeddevcnt; /* Number of devs that require rtnl lock. */
>>> diff --git a/net/sched/cls_api.c b/net/sched/cls_api.c
>>> index ca5676b2668e..397c3d29659c 100644
>>> --- a/net/sched/cls_api.c
>>> +++ b/net/sched/cls_api.c
>>> @@ -3483,6 +3483,8 @@ static void tcf_block_offload_inc(struct tcf_block *block, u32 *flags)
>>> if (*flags & TCA_CLS_FLAGS_IN_HW)
>>> return;
>>> *flags |= TCA_CLS_FLAGS_IN_HW;
>>> + if (tc_skip_sw(*flags))
>>> + atomic_inc(&block->skipswcnt);
>>> atomic_inc(&block->offloadcnt);
>>> }
>>>
>>> @@ -3491,6 +3493,8 @@ static void tcf_block_offload_dec(struct tcf_block *block, u32 *flags)
>>> if (!(*flags & TCA_CLS_FLAGS_IN_HW))
>>> return;
>>> *flags &= ~TCA_CLS_FLAGS_IN_HW;
>>> + if (tc_skip_sw(*flags))
>>> + atomic_dec(&block->skipswcnt);
>>> atomic_dec(&block->offloadcnt);
>>> }
>>>
>>> --
>>> 2.43.0
>>>


2024-02-16 13:58:12

by Jiri Pirko

[permalink] [raw]
Subject: Re: [PATCH net-next 1/3] net: sched: cls_api: add skip_sw counter

Thu, Feb 15, 2024 at 05:04:42PM CET, [email protected] wrote:
>Maintain a count of skip_sw filters.
>
>This counter is protected by the cb_lock, and is updated
>at the same time as offloadcnt.
>
>Signed-off-by: Asbj?rn Sloth T?nnesen <[email protected]>

Reviewed-by: Jiri Pirko <[email protected]>