From mboxrd@z Thu Jan 1 00:00:00 1970 From: Vlad Buslov Subject: Re: [PATCH 05/14] net: sched: always take reference to action Date: Mon, 14 May 2018 21:49:07 +0300 Message-ID: References: <1526308035-12484-1-git-send-email-vladbu@mellanox.com> <1526308035-12484-6-git-send-email-vladbu@mellanox.com> <20180514162301.GC2134@nanopsycho.orion> Mime-Version: 1.0 Content-Type: text/plain Cc: netdev@vger.kernel.org, davem@davemloft.net, jhs@mojatatu.com, xiyou.wangcong@gmail.com, pablo@netfilter.org, kadlec@blackhole.kfki.hu, fw@strlen.de, ast@kernel.org, daniel@iogearbox.net, edumazet@google.com, keescook@chromium.org, linux-kernel@vger.kernel.org, netfilter-devel@vger.kernel.org, coreteam@netfilter.org, kliteyn@mellanox.com To: Jiri Pirko Return-path: In-reply-to: <20180514162301.GC2134@nanopsycho.orion> Sender: linux-kernel-owner@vger.kernel.org List-Id: netdev.vger.kernel.org On Mon 14 May 2018 at 16:23, Jiri Pirko wrote: > Mon, May 14, 2018 at 04:27:06PM CEST, vladbu@mellanox.com wrote: >>Without rtnl lock protection it is no longer safe to use pointer to tc >>action without holding reference to it. (it can be destroyed concurrently) >> >>Remove unsafe action idr lookup function. Instead of it, implement safe tcf >>idr check function that atomically looks up action in idr and increments >>its reference and bind counters. >> >>Implement both action search and check using new safe function. >> >>Signed-off-by: Vlad Buslov >>--- >> net/sched/act_api.c | 38 ++++++++++++++++---------------------- >> 1 file changed, 16 insertions(+), 22 deletions(-) >> >>diff --git a/net/sched/act_api.c b/net/sched/act_api.c >>index 1331beb..9459cce 100644 >>--- a/net/sched/act_api.c >>+++ b/net/sched/act_api.c >>@@ -284,44 +284,38 @@ int tcf_generic_walker(struct tc_action_net *tn, struct sk_buff *skb, >> } >> EXPORT_SYMBOL(tcf_generic_walker); >> >>-static struct tc_action *tcf_idr_lookup(u32 index, struct tcf_idrinfo *idrinfo) >>+bool __tcf_idr_check(struct tc_action_net *tn, u32 index, struct tc_action **a, >>+ int bind) >> { >>- struct tc_action *p = NULL; >>+ struct tcf_idrinfo *idrinfo = tn->idrinfo; >>+ struct tc_action *p; >> >> spin_lock_bh(&idrinfo->lock); > > Why "_bh" variant is necessary here? It is not my code. > >> p = idr_find(&idrinfo->action_idr, index); >>+ if (p) { >>+ refcount_inc(&p->tcfa_refcnt); >>+ if (bind) >>+ atomic_inc(&p->tcfa_bindcnt); >>+ } >> spin_unlock_bh(&idrinfo->lock); > > [...]