Re: [PATCH net-next 2/3] net: sched: cls_api: add filter counter

["Asbjørn Sloth Tønnesen" <ast@fiberby.net>]

Hi Jiri,

Thanks for the review.

On 2/15/24 17:25, Jiri Pirko wrote:
> Thu, Feb 15, 2024 at 05:04:43PM CET, ast@fiberby.net wrote:
>> Maintain a count of filters per block.
>>
>> Counter updates are protected by cb_lock, which is
>> also used to protect the offload counters.
>>
>> Signed-off-by: Asbjørn Sloth Tønnesen <ast@fiberby.net>
>> ---
>> include/net/sch_generic.h |  2 ++
>> net/sched/cls_api.c       | 20 ++++++++++++++++++++
>> 2 files changed, 22 insertions(+)
>>
>> diff --git a/include/net/sch_generic.h b/include/net/sch_generic.h
>> index 46a63d1818a0..7af0621db226 100644
>> --- a/include/net/sch_generic.h
>> +++ b/include/net/sch_generic.h
>> @@ -427,6 +427,7 @@ struct tcf_proto {
>> 	 */
>> 	spinlock_t		lock;
>> 	bool			deleting;
>> +	bool			counted;
>> 	refcount_t		refcnt;
>> 	struct rcu_head		rcu;
>> 	struct hlist_node	destroy_ht_node;
>> @@ -476,6 +477,7 @@ struct tcf_block {
>> 	struct flow_block flow_block;
>> 	struct list_head owner_list;
>> 	bool keep_dst;
>> +	atomic_t filtercnt; /* Number of filters */
>> 	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 */
>> diff --git a/net/sched/cls_api.c b/net/sched/cls_api.c
>> index 397c3d29659c..c750cb662142 100644
>> --- a/net/sched/cls_api.c
>> +++ b/net/sched/cls_api.c
>> @@ -411,11 +411,13 @@ static void tcf_proto_get(struct tcf_proto *tp)
>> }
>>
>> static void tcf_chain_put(struct tcf_chain *chain);
>> +static void tcf_block_filter_cnt_update(struct tcf_block *block, bool *counted, bool add);
>>
>> static void tcf_proto_destroy(struct tcf_proto *tp, bool rtnl_held,
>> 			      bool sig_destroy, struct netlink_ext_ack *extack)
>> {
>> 	tp->ops->destroy(tp, rtnl_held, extack);
>> +	tcf_block_filter_cnt_update(tp->chain->block, &tp->counted, false);
>> 	if (sig_destroy)
>> 		tcf_proto_signal_destroyed(tp->chain, tp);
>> 	tcf_chain_put(tp->chain);
>> @@ -2364,6 +2366,7 @@ static int tc_new_tfilter(struct sk_buff *skb, struct nlmsghdr *n,
>> 	err = tp->ops->change(net, skb, tp, cl, t->tcm_handle, tca, &fh,
>> 			      flags, extack);
>> 	if (err == 0) {
>> +		tcf_block_filter_cnt_update(block, &tp->counted, true);
>> 		tfilter_notify(net, skb, n, tp, block, q, parent, fh,
>> 			       RTM_NEWTFILTER, false, rtnl_held, extack);
>> 		tfilter_put(tp, fh);
>> @@ -3478,6 +3481,23 @@ int tcf_exts_dump_stats(struct sk_buff *skb, struct tcf_exts *exts)
>> }
>> EXPORT_SYMBOL(tcf_exts_dump_stats);
>>
>> +static void tcf_block_filter_cnt_update(struct tcf_block *block, bool *counted, bool add)
> 
> Can't you move this up to avoid forward declaration?

Sure, will do that in v2.

I had considered it, but in the end decided to keep it next to the related offloadcnt logic.


>> +{
>> +	lockdep_assert_not_held(&block->cb_lock);
>> +
>> +	down_write(&block->cb_lock);
>> +	if (*counted != add) {
>> +		if (add) {
>> +			atomic_inc(&block->filtercnt);
>> +			*counted = true;
>> +		} else {
>> +			atomic_dec(&block->filtercnt);
>> +			*counted = false;
>> +		}
>> +	}
>> +	up_write(&block->cb_lock);
>> +}
>> +
>> static void tcf_block_offload_inc(struct tcf_block *block, u32 *flags)
>> {
>> 	if (*flags & TCA_CLS_FLAGS_IN_HW)
>> -- 
>> 2.43.0
>>

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