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Fri, 24 Oct 2025 10:21:14 +0800 Date: Fri, 24 Oct 2025 10:21:14 +0800 From: Dust Li To: Julian Anastasov , Simon Horman Cc: lvs-devel@vger.kernel.org, netfilter-devel@vger.kernel.org, Jiejian Wu , rcu@vger.kernel.org Subject: Re: [PATCHv6 net-next 03/14] ipvs: some service readers can use RCU Message-ID: Reply-To: dust.li@linux.alibaba.com References: <20251019155711.67609-1-ja@ssi.bg> <20251019155711.67609-4-ja@ssi.bg> Precedence: bulk X-Mailing-List: netfilter-devel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20251019155711.67609-4-ja@ssi.bg> On 2025-10-19 18:57:00, Julian Anastasov wrote: >Some places walk the services under mutex but they can just use RCU: > >* ip_vs_dst_event() uses ip_vs_forget_dev() which uses its own lock > to modify dest >* ip_vs_genl_dump_services(): ip_vs_genl_fill_service() just fills skb >* ip_vs_genl_parse_service(): move RCU lock to callers > ip_vs_genl_set_cmd(), ip_vs_genl_dump_dests() and ip_vs_genl_get_cmd() >* ip_vs_genl_dump_dests(): just fill skb > >Signed-off-by: Julian Anastasov Reviewed-by: Dust Li Best regards, Dust >--- > net/netfilter/ipvs/ip_vs_ctl.c | 47 +++++++++++++++++----------------- > 1 file changed, 23 insertions(+), 24 deletions(-) > >diff --git a/net/netfilter/ipvs/ip_vs_ctl.c b/net/netfilter/ipvs/ip_vs_ctl.c >index 2fb9034b4f53..b18d08d79bcb 100644 >--- a/net/netfilter/ipvs/ip_vs_ctl.c >+++ b/net/netfilter/ipvs/ip_vs_ctl.c >@@ -1759,23 +1759,21 @@ static int ip_vs_dst_event(struct notifier_block *this, unsigned long event, > if (event != NETDEV_DOWN || !ipvs) > return NOTIFY_DONE; > IP_VS_DBG(3, "%s() dev=%s\n", __func__, dev->name); >- mutex_lock(&ipvs->service_mutex); >+ rcu_read_lock(); > for (idx = 0; idx < IP_VS_SVC_TAB_SIZE; idx++) { >- hlist_for_each_entry(svc, &ipvs->svc_table[idx], s_list) { >- list_for_each_entry(dest, &svc->destinations, >- n_list) { >+ hlist_for_each_entry_rcu(svc, &ipvs->svc_table[idx], s_list) >+ list_for_each_entry_rcu(dest, &svc->destinations, >+ n_list) > ip_vs_forget_dev(dest, dev); >- } >- } > >- hlist_for_each_entry(svc, &ipvs->svc_fwm_table[idx], f_list) { >- list_for_each_entry(dest, &svc->destinations, >- n_list) { >+ hlist_for_each_entry_rcu(svc, &ipvs->svc_fwm_table[idx], f_list) >+ list_for_each_entry_rcu(dest, &svc->destinations, >+ n_list) > ip_vs_forget_dev(dest, dev); >- } >- } > } >+ rcu_read_unlock(); > >+ mutex_lock(&ipvs->service_mutex); > spin_lock_bh(&ipvs->dest_trash_lock); > list_for_each_entry(dest, &ipvs->dest_trash, t_list) { > ip_vs_forget_dev(dest, dev); >@@ -3318,9 +3316,9 @@ static int ip_vs_genl_fill_service(struct sk_buff *skb, > goto nla_put_failure; > } > >- sched = rcu_dereference_protected(svc->scheduler, 1); >+ sched = rcu_dereference(svc->scheduler); > sched_name = sched ? sched->name : "none"; >- pe = rcu_dereference_protected(svc->pe, 1); >+ pe = rcu_dereference(svc->pe); > if (nla_put_string(skb, IPVS_SVC_ATTR_SCHED_NAME, sched_name) || > (pe && nla_put_string(skb, IPVS_SVC_ATTR_PE_NAME, pe->name)) || > nla_put(skb, IPVS_SVC_ATTR_FLAGS, sizeof(flags), &flags) || >@@ -3374,9 +3372,9 @@ static int ip_vs_genl_dump_services(struct sk_buff *skb, > struct net *net = sock_net(skb->sk); > struct netns_ipvs *ipvs = net_ipvs(net); > >- mutex_lock(&ipvs->service_mutex); >+ rcu_read_lock(); > for (i = 0; i < IP_VS_SVC_TAB_SIZE; i++) { >- hlist_for_each_entry(svc, &ipvs->svc_table[i], s_list) { >+ hlist_for_each_entry_rcu(svc, &ipvs->svc_table[i], s_list) { > if (++idx <= start) > continue; > if (ip_vs_genl_dump_service(skb, svc, cb) < 0) { >@@ -3387,7 +3385,7 @@ static int ip_vs_genl_dump_services(struct sk_buff *skb, > } > > for (i = 0; i < IP_VS_SVC_TAB_SIZE; i++) { >- hlist_for_each_entry(svc, &ipvs->svc_fwm_table[i], f_list) { >+ hlist_for_each_entry_rcu(svc, &ipvs->svc_fwm_table[i], f_list) { > if (++idx <= start) > continue; > if (ip_vs_genl_dump_service(skb, svc, cb) < 0) { >@@ -3398,7 +3396,7 @@ static int ip_vs_genl_dump_services(struct sk_buff *skb, > } > > nla_put_failure: >- mutex_unlock(&ipvs->service_mutex); >+ rcu_read_unlock(); > cb->args[0] = idx; > > return skb->len; >@@ -3454,13 +3452,11 @@ static int ip_vs_genl_parse_service(struct netns_ipvs *ipvs, > usvc->fwmark = 0; > } > >- rcu_read_lock(); > if (usvc->fwmark) > svc = __ip_vs_svc_fwm_find(ipvs, usvc->af, usvc->fwmark); > else > svc = __ip_vs_service_find(ipvs, usvc->af, usvc->protocol, > &usvc->addr, usvc->port); >- rcu_read_unlock(); > *ret_svc = svc; > > /* If a full entry was requested, check for the additional fields */ >@@ -3587,7 +3583,7 @@ static int ip_vs_genl_dump_dests(struct sk_buff *skb, > struct net *net = sock_net(skb->sk); > struct netns_ipvs *ipvs = net_ipvs(net); > >- mutex_lock(&ipvs->service_mutex); >+ rcu_read_lock(); > > /* Try to find the service for which to dump destinations */ > if (nlmsg_parse_deprecated(cb->nlh, GENL_HDRLEN, attrs, IPVS_CMD_ATTR_MAX, ip_vs_cmd_policy, cb->extack)) >@@ -3599,7 +3595,7 @@ static int ip_vs_genl_dump_dests(struct sk_buff *skb, > goto out_err; > > /* Dump the destinations */ >- list_for_each_entry(dest, &svc->destinations, n_list) { >+ list_for_each_entry_rcu(dest, &svc->destinations, n_list) { > if (++idx <= start) > continue; > if (ip_vs_genl_dump_dest(skb, dest, cb) < 0) { >@@ -3612,7 +3608,7 @@ static int ip_vs_genl_dump_dests(struct sk_buff *skb, > cb->args[0] = idx; > > out_err: >- mutex_unlock(&ipvs->service_mutex); >+ rcu_read_unlock(); > > return skb->len; > } >@@ -3915,9 +3911,12 @@ static int ip_vs_genl_set_cmd(struct sk_buff *skb, struct genl_info *info) > if (cmd == IPVS_CMD_NEW_SERVICE || cmd == IPVS_CMD_SET_SERVICE) > need_full_svc = true; > >+ /* We use function that requires RCU lock */ >+ rcu_read_lock(); > ret = ip_vs_genl_parse_service(ipvs, &usvc, > info->attrs[IPVS_CMD_ATTR_SERVICE], > need_full_svc, &svc); >+ rcu_read_unlock(); > if (ret) > goto out; > >@@ -4037,7 +4036,7 @@ static int ip_vs_genl_get_cmd(struct sk_buff *skb, struct genl_info *info) > if (!msg) > return -ENOMEM; > >- mutex_lock(&ipvs->service_mutex); >+ rcu_read_lock(); > > reply = genlmsg_put_reply(msg, info, &ip_vs_genl_family, 0, reply_cmd); > if (reply == NULL) >@@ -4105,7 +4104,7 @@ static int ip_vs_genl_get_cmd(struct sk_buff *skb, struct genl_info *info) > out_err: > nlmsg_free(msg); > out: >- mutex_unlock(&ipvs->service_mutex); >+ rcu_read_unlock(); > > return ret; > } >-- >2.51.0 >