netdev - Re: [PATCH net 0/2] net/sched: avoid walk() while deleting filters that still use rtnl

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Date:   Tue, 24 Dec 2019 07:49:03 -0500
From:   Jamal Hadi Salim <jhs@...atatu.com>
To:     Davide Caratti <dcaratti@...hat.com>,
        "David S. Miller" <davem@...emloft.net>, netdev@...r.kernel.org,
        Vlad Buslov <vladbu@...lanox.com>
Subject: Re: [PATCH net 0/2] net/sched: avoid walk() while deleting filters
 that still use rtnl_lock

Davide,
Thanks for the effort. Looks good to me - will wait for you to
address Vlad's comments then run a couple of tests...

cheers,
jamal

On 2019-12-24 4:30 a.m., Davide Caratti wrote:
> we don't need to use walk() on deletion of TC filters, at least for those
> implementations that don't have TCF_PROTO_OPS_DOIT_UNLOCKED.
> 
> - patch 1/2 restores walk() semantic in cls_u32, that was recently
>    changed to fix semi-configured filters in the error path of u32_change().
> - patch 2/2 moves the delete_empty() logic to cls_flower, the only filter
>    that currently needs to guard against concurrent insert/delete.
>    For flower, the current delete_empty() still [ab,]uses walk(), to
>    preserve the bugfixes introduced by [1] and [2]: a follow-up commit
>    in the future can implement a proper delete_empty() that avoids calls
>    to fl_walk().
> 
> (tested with tdc "concurrency", "matchall", "basic" and "u32")
> 
> [1] 6676d5e416ee ("net: sched: set dedicated tcf_walker flag when tp is empty")
> [2] 8b64678e0af8 ("net: sched: refactor tp insert/delete for concurrent execution")
> 
> Davide Caratti (2):
>    Revert "net/sched: cls_u32: fix refcount leak in the error path of
>      u32_change()"
>    net/sched: add delete_empty() to filters and use it in cls_flower
> 
>   include/net/sch_generic.h |  2 ++
>   net/sched/cls_api.c       | 29 ++++-------------------------
>   net/sched/cls_flower.c    | 23 +++++++++++++++++++++++
>   net/sched/cls_u32.c       | 25 -------------------------
>   4 files changed, 29 insertions(+), 50 deletions(-)
>