> On 29 Oct 2024, at 18:02, Xin Long <lucien.xin@xxxxxxxxx> wrote:
>
> CAUTION: External E-Mail - Use caution with links and attachments
>
>
> On Mon, Oct 28, 2024 at 4:10 AM Gilad Naaman <gnaaman@xxxxxxxxxxxxx> wrote:
>>
>> Avoid modifying or enqueuing new events if it's possible to tell that no
>> one will consume them.
>>
>> Since enqueueing requires searching the current queue for opposite
>> events for the same address, adding addresses en-masse turns this
>> inetaddr_event into a bottle-neck, as it will get slower and slower
>> with each address added.
>>
>> Signed-off-by: Gilad Naaman <gnaaman@xxxxxxxxxxxxx>
>> ---
>> net/sctp/protocol.c | 14 ++++++++++++++
>> 1 file changed, 14 insertions(+)
>>
>> diff --git a/net/sctp/protocol.c b/net/sctp/protocol.c
>> index 39ca5403d4d7..2e548961b740 100644
>> --- a/net/sctp/protocol.c
>> +++ b/net/sctp/protocol.c
>> @@ -738,6 +738,20 @@ void sctp_addr_wq_mgmt(struct net *net, struct sctp_sockaddr_entry *addr, int cm
>> */
>>
>> spin_lock_bh(&net->sctp.addr_wq_lock);
>> +
>> + /* Avoid searching the queue or modifying it if there are no consumers,
>> + * as it can lead to performance degradation if addresses are modified
>> + * en-masse.
>> + *
>> + * If the queue already contains some events, update it anyway to avoid
>> + * ugly races between new sessions and new address events.
>> + */
>> + if (list_empty(&net->sctp.auto_asconf_splist) &&
>> + list_empty(&net->sctp.addr_waitq)) {
>> + spin_unlock_bh(&net->sctp.addr_wq_lock);
>> + return;
>
> What if after this but before the addr is deleted from local_addr_list in
> sctp_inetaddr_event(), a new SCTP association is created with these addrs
> in local_addr_list, will it miss this asconf addr_del?
>
> Thanks.
Great point.
I think this can be solved by making sure `list_del_rcu(&addr->list);` is called
before `sctp_addr_wq_mgmt`.
I’ll resend this after I manage to un-bork my git-send-email config.
Thank you!
>
>> + }
>> +
>> /* Offsets existing events in addr_wq */
>> addrw = sctp_addr_wq_lookup(net, addr);
>> if (addrw) {
>> --
>> 2.46.0
>>
