From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.1 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id D4D49C43331 for ; Wed, 1 Apr 2020 16:07:06 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 80D6E2071A for ; Wed, 1 Apr 2020 16:07:06 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=microchip.com header.i=@microchip.com header.b="vgav4cg3" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732292AbgDAQHF (ORCPT ); Wed, 1 Apr 2020 12:07:05 -0400 Received: from esa4.microchip.iphmx.com ([68.232.154.123]:64108 "EHLO esa4.microchip.iphmx.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1732201AbgDAQHC (ORCPT ); Wed, 1 Apr 2020 12:07:02 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=microchip.com; i=@microchip.com; q=dns/txt; s=mchp; t=1585757222; x=1617293222; h=date:from:to:cc:subject:message-id:references: mime-version:in-reply-to; bh=KMNfMH5QecfKMxDXYov9/YsNZ6rjdfmxIcYE+JqlR+o=; b=vgav4cg3Iv93hWB/i7s7PG5a33fd34MYsspRpWPy7sX/MJ4lMZb02ET5 L/aDqQ1qOlQlBVKXuxhy+2fqkKgHY3f3y3dTWkNsq0r9gwsUP81qe99o4 SpYj9YCb9TdL9qqVNWWeTIJhXhezs4/lT3Sf57gOgdqUJMOuwUstYYY6U K7Q36L8H0t7wtS43TA1XD93Bqdazw95nk49s5ujbcF8LOvXFb29PkZ/t5 hIl86vPqPjkIPlPi2v/CDXjFU4xhTCKVUsiAl7rKDZJnDM5PZSD/6n7EN SjFfBgcMyOBGnf0vAKT5J356kBfpjw6gl5tenYjdLCMBy/2HI/rYQt1zE Q==; IronPort-SDR: YHNlULN3WLc2kYjP8f1K6G25CQcPhDXpWJyxcNTlVJ6HYtH1u5p9we11R0kwpDWRQifLS5l7j+ UGTacGgMMkQoShhSLWxKGkY2C/+H49zprAXRvG3R9oUROKSIDHzcb9wwpbnV93zrxclzNqWKQp UL0O/xFHhqyxBtLFdjitxEHtyXmPWEyLB5fSz5w33TdoziX9I1/wHe6MuNBzGsy199wBN6sGcT +K09FNOhTmi46Baw+ituDFh3ETF5yOOpvb7vtDFlv5hq732UTAKuN4dNqB/JnL6vsXl1NhFwiJ lFU= X-IronPort-AV: E=Sophos;i="5.72,332,1580799600"; d="scan'208";a="69092985" Received: from smtpout.microchip.com (HELO email.microchip.com) ([198.175.253.82]) by esa4.microchip.iphmx.com with ESMTP/TLS/AES256-SHA256; 01 Apr 2020 09:06:23 -0700 Received: from chn-vm-ex01.mchp-main.com (10.10.85.143) by chn-vm-ex02.mchp-main.com (10.10.85.144) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.1713.5; Wed, 1 Apr 2020 09:06:22 -0700 Received: from localhost (10.10.115.15) by chn-vm-ex01.mchp-main.com (10.10.85.143) with Microsoft SMTP Server id 15.1.1713.5 via Frontend Transport; Wed, 1 Apr 2020 09:06:28 -0700 Date: Wed, 1 Apr 2020 18:06:21 +0200 From: Horatiu Vultur To: Nikolay Aleksandrov CC: , , , , , , , , , , Subject: Re: [RFC net-next v4 7/9] bridge: mrp: Connect MRP api with the switchev API Message-ID: <20200401160621.4fq66xwamuhmzxdb@soft-dev3.microsemi.net> References: <20200327092126.15407-1-horatiu.vultur@microchip.com> <20200327092126.15407-8-horatiu.vultur@microchip.com> <7e85b9fe-f518-0c5a-0891-6f64755407c3@cumulusnetworks.com> MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Disposition: inline In-Reply-To: <7e85b9fe-f518-0c5a-0891-6f64755407c3@cumulusnetworks.com> User-Agent: NeoMutt/20180716 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The 03/30/2020 19:11, Nikolay Aleksandrov wrote: > EXTERNAL EMAIL: Do not click links or open attachments unless you know the content is safe > > On 27/03/2020 11:21, Horatiu Vultur wrote: > > Implement the MRP api. > > > > In case the HW can't generate MRP Test frames then the SW will try to generate > > the frames. In case that also the SW will fail in generating the frames then a > > error is return to the userspace. The userspace is responsible to generate all > > the other MRP frames regardless if the test frames are generated by HW or SW. > > > > The forwarding/termination of MRP frames is happening in the kernel and is done > > by the MRP instance. The userspace application doesn't do the forwarding. > > > > Signed-off-by: Horatiu Vultur > > --- > > net/bridge/br_mrp.c | 514 ++++++++++++++++++++++++++++++++++++++++++++ > > 1 file changed, 514 insertions(+) > > create mode 100644 net/bridge/br_mrp.c > > > > Hi, Hi Nik, > In general the RCU usage needs more work. Thanks for the detailed review, this is my first time when I use the RCU, so I might need to spend more time on time. > Also I might've missed it, but where do you > handle bridge port delete which is used in mrp ? When a port is deleted, then the userspace application will be notified and then the userspace will remove the MRP instance. Because there is no point to have a MRP instance with only 1 port. And the function that delets the MRP instance is br_mrp_del. > Also do you actually need the mrp->lock ? I think I should be fine not to use mrp->lock because already the rtnl lock is taken. > > > diff --git a/net/bridge/br_mrp.c b/net/bridge/br_mrp.c > > new file mode 100644 > > index 000000000000..f1de792d7a6e > > --- /dev/null > > +++ b/net/bridge/br_mrp.c > > @@ -0,0 +1,514 @@ > > +// SPDX-License-Identifier: GPL-2.0-or-later > > + > > +#include "br_private_mrp.h" > > + > > +static const u8 mrp_test_dmac[ETH_ALEN] = { 0x1, 0x15, 0x4e, 0x0, 0x0, 0x1 }; > > + > > +static struct net_bridge_port *br_mrp_get_port(struct net_bridge *br, > > + u32 ifindex) > > +{ > > + struct net_bridge_port *res = NULL; > > + struct net_bridge_port *port; > > + > > + spin_lock_bh(&br->lock); > > + > > This is called under RTNL, you don't need the br->lock. Will be fix in the next patch series. > > > + list_for_each_entry(port, &br->port_list, list) { > > + if (port->dev->ifindex == ifindex) { > > + res = port; > > + break; > > + } > > + } > > + > > + spin_unlock_bh(&br->lock); > > + > > + return res; > > +} > > + > > +static struct br_mrp *br_mrp_find_id(struct net_bridge *br, u32 ring_id) > > +{ > > + struct br_mrp *res = NULL; > > + struct br_mrp *mrp; > > + > > + rcu_read_lock(); > > + > > This is generally a bad pattern because it can hide legitimate bugs and make > it harder to debug. Can you give me a little more details why is a bad pattern? I have tried to read about rcu from here[1][2]. But I couldn't see anything about this. > > > + list_for_each_entry_rcu(mrp, &br->mrp_list, list) { > > + if (mrp->ring_id == ring_id) { > > + res = mrp; > > + break; > > + } > > + } > > + > > + rcu_read_unlock(); > > + > > + return res; > > +} > > + > > +static struct br_mrp *br_mrp_find_port(struct net_bridge *br, > > + struct net_bridge_port *p) > > +{ > > + struct br_mrp *res = NULL; > > + struct br_mrp *mrp; > > + > > + rcu_read_lock(); > > + > > + list_for_each_entry_rcu(mrp, &br->mrp_list, list) { > > + if (rcu_dereference(mrp->p_port) == p || > > + rcu_dereference(mrp->s_port) == p) { > > rcu_access_pointer() is ok for comparisons Will be fix in the next patch series. > > > + res = mrp; > > + break; > > + } > > + } > > + > > + rcu_read_unlock(); > > + > > + return res; > > +} > > + > > +static int br_mrp_next_seq(struct br_mrp *mrp) > > +{ > > + mrp->seq_id++; > > + return mrp->seq_id; > > +} > > + > > +static struct sk_buff *br_mrp_skb_alloc(struct net_bridge_port *p, > > + const u8 *src, const u8 *dst) > > +{ > > + struct ethhdr *eth_hdr; > > + struct sk_buff *skb; > > + u16 *version; > > + > > + skb = dev_alloc_skb(MRP_MAX_FRAME_LENGTH); > > + if (!skb) > > + return NULL; > > + > > + skb->dev = p->dev; > > + skb->protocol = htons(ETH_P_MRP); > > + skb->priority = MRP_FRAME_PRIO; > > + skb_reserve(skb, sizeof(*eth_hdr)); > > + > > + eth_hdr = skb_push(skb, sizeof(*eth_hdr)); > > + ether_addr_copy(eth_hdr->h_dest, dst); > > + ether_addr_copy(eth_hdr->h_source, src); > > + eth_hdr->h_proto = htons(ETH_P_MRP); > > + > > + version = skb_put(skb, sizeof(*version)); > > + *version = cpu_to_be16(MRP_VERSION); > > + > > + return skb; > > +} > > + > > +static void br_mrp_skb_tlv(struct sk_buff *skb, > > + enum br_mrp_tlv_header_type type, > > + u8 length) > > +{ > > + struct br_mrp_tlv_hdr *hdr; > > + > > + hdr = skb_put(skb, sizeof(*hdr)); > > + hdr->type = type; > > + hdr->length = length; > > +} > > + > > +static void br_mrp_skb_common(struct sk_buff *skb, struct br_mrp *mrp) > > +{ > > + struct br_mrp_common_hdr *hdr; > > + > > + br_mrp_skb_tlv(skb, BR_MRP_TLV_HEADER_COMMON, sizeof(*hdr)); > > + > > + hdr = skb_put(skb, sizeof(*hdr)); > > + hdr->seq_id = cpu_to_be16(br_mrp_next_seq(mrp)); > > + memset(hdr->domain, 0xff, MRP_DOMAIN_UUID_LENGTH); > > +} > > + > > +static struct sk_buff *br_mrp_alloc_test_skb(struct br_mrp *mrp, > > + struct net_device *dev, > > + enum br_mrp_port_role_type port_role) > > +{ > > + struct net_bridge_port *p = br_port_get_rtnl(dev); > > + struct br_mrp_ring_test_hdr *hdr = NULL; > > + struct net_bridge *br = p->br; > > + struct sk_buff *skb = NULL; > > + > > + if (!p) > > + return NULL; > > + > > + br = p->br; > > + > > + skb = br_mrp_skb_alloc(p, p->dev->dev_addr, mrp_test_dmac); > > + if (!skb) > > + return NULL; > > + > > + br_mrp_skb_tlv(skb, BR_MRP_TLV_HEADER_RING_TEST, sizeof(*hdr)); > > + hdr = skb_put(skb, sizeof(*hdr)); > > + > > + hdr->prio = cpu_to_be16(MRP_DEFAULT_PRIO); > > + ether_addr_copy(hdr->sa, p->br->dev->dev_addr); > > + hdr->port_role = cpu_to_be16(port_role); > > + hdr->state = cpu_to_be16(mrp->ring_state); > > + hdr->transitions = cpu_to_be16(mrp->ring_transitions); > > + hdr->timestamp = cpu_to_be32(jiffies_to_msecs(jiffies)); > > + > > + br_mrp_skb_common(skb, mrp); > > + br_mrp_skb_tlv(skb, BR_MRP_TLV_HEADER_END, 0x0); > > + > > + return skb; > > +} > > + > > +static void br_mrp_test_work_expired(struct work_struct *work) > > +{ > > + struct delayed_work *del_work = to_delayed_work(work); > > + struct br_mrp *mrp = container_of(del_work, struct br_mrp, test_work); > > + bool notify_open = false; > > + struct sk_buff *skb; > > + > > Since this runs asynchronously what happens if the port is deleted ? Later I have checks to see if the port is no NULL. Is not good enough? I have these rcu_access_pointer checks and before that I disable the interrupts and get the rcu lock. > > > + if (time_before_eq(mrp->test_end, jiffies)) > > + return; > > + > > + if (mrp->test_count_miss < mrp->test_max_miss) { > > + mrp->test_count_miss++; > > + } else { > > + /* Notify that the ring is open only if the ring state is > > + * closed, otherwise it would continue to notify at every > > + * interval. > > + */ > > + if (mrp->ring_state == BR_MRP_RING_STATE_CLOSED) > > + notify_open = true; > > + } > > + > > + local_bh_disable(); > > + rcu_read_lock(); > > + > > + if (!rcu_access_pointer(mrp->p_port) || > > + !rcu_access_pointer(mrp->s_port)) > > + goto out; > > + > > + /* Is it possible here to get call to delete the bridge port? If yes > > + * I need to protect it > > + */ > > + dev_hold(rcu_dereference(mrp->p_port)->dev); > > + > > This looks all wrong, p_port can become NULL here and you'll deref it. By disabling the interrupts and taking the rcu read lock, will I not be sure that no one can access the p_port? If is not true, how the p_port can become NULL? > > > + skb = br_mrp_alloc_test_skb(mrp, rcu_dereference(mrp->p_port)->dev, > > + BR_MRP_PORT_ROLE_PRIMARY); > > + if (!skb) > > + goto out; > > + > > + skb_reset_network_header(skb); > > + dev_queue_xmit(skb); > > + > > + if (notify_open && !mrp->ring_role_offloaded) > > + br_mrp_port_open(rcu_dereference(mrp->p_port)->dev, true); > > + > > + dev_put(rcu_dereference(mrp->p_port)->dev); > > + > > + dev_hold(rcu_dereference(mrp->s_port)->dev); > > + > > same here > > > + skb = br_mrp_alloc_test_skb(mrp, rcu_dereference(mrp->s_port)->dev, > > + BR_MRP_PORT_ROLE_SECONDARY); > > + if (!skb) > > + goto out; > > + > > + skb_reset_network_header(skb); > > + dev_queue_xmit(skb); > > + > > + if (notify_open && !mrp->ring_role_offloaded) > > + br_mrp_port_open(rcu_dereference(mrp->s_port)->dev, true); > > + > > + dev_put(rcu_dereference(mrp->s_port)->dev); > > + > > +out: > > + rcu_read_unlock(); > > + local_bh_enable(); > > + > > + queue_delayed_work(system_wq, &mrp->test_work, > > + usecs_to_jiffies(mrp->test_interval)); > > +} > > + > > +/* Adds a new MRP instance. > > + * note: called under rtnl_lock > > + */ > > +int br_mrp_add(struct net_bridge *br, struct br_mrp_instance *instance) > > +{ > > + struct net_bridge_port *p; > > + struct br_mrp *mrp; > > + > > + /* If the ring exists, it is not possible to create another one with the > > + * same ring_id > > + */ > > + mrp = br_mrp_find_id(br, instance->ring_id); > > + if (mrp) > > + return -EINVAL; > > + > > + if (!br_mrp_get_port(br, instance->p_ifindex) || > > + !br_mrp_get_port(br, instance->s_ifindex)) > > + return -EINVAL; > > + > > + mrp = devm_kzalloc(&br->dev->dev, sizeof(struct br_mrp), GFP_KERNEL); > > + if (!mrp) > > + return -ENOMEM; > > + > > + /* I think is not needed because this can be replaced with rtnl lock*/ > > + spin_lock_init(&mrp->lock); > > + spin_lock(&mrp->lock); > > + > > + mrp->br = br; > > Is this field (mrp->br) used anywhere ? Not anymore. I can remove it in the next patch series. > > > + mrp->ring_id = instance->ring_id; > > + > > + p = br_mrp_get_port(br, instance->p_ifindex); > > + p->state = BR_STATE_FORWARDING; > > + p->flags |= BR_MRP_AWARE; > > + rcu_assign_pointer(mrp->p_port, p); > > + > > + p = br_mrp_get_port(br, instance->s_ifindex); > > + p->state = BR_STATE_FORWARDING; > > + p->flags |= BR_MRP_AWARE; > > + rcu_assign_pointer(mrp->s_port, p); > > + > > + br_mrp_switchdev_add(mrp); > > + > > + spin_unlock(&mrp->lock); > > + synchronize_rcu(); > > Why do you need the synchronize here? Actually this shouldn't be after the list_add_tail_rcu? Because I am thinking that some can read the list at the same time I am change it. > > > + > > + list_add_tail_rcu(&mrp->list, &br->mrp_list); > > + INIT_DELAYED_WORK(&mrp->test_work, br_mrp_test_work_expired); > > + > > + return 0; > > +} > > + > > +/* Deletes existing MRP instance. > > + * note: called under rtnl_lock > > + */ > > +int br_mrp_del(struct net_bridge *br, struct br_mrp_instance *instance) > > +{ > > + struct br_mrp *mrp = br_mrp_find_id(br, instance->ring_id); > > + struct net_bridge_port *p; > > + > > + if (!mrp) > > + return -EINVAL; > > + > > + /* Stop sending MRP_Test frames */ > > + cancel_delayed_work(&mrp->test_work); > > cancel_delayed_work_sync() if you'd like to make sure it's stopped and finished (if it was running > during this) Will be fixed in the next patch series. > > > + br_mrp_switchdev_send_ring_test(mrp, 0, 0, 0); > > + > > + spin_lock(&mrp->lock); > > + > > + br_mrp_switchdev_del(mrp); > > + > > + /* Reset the ports */ > > + p = rcu_dereference_protected(mrp->p_port, lockdep_is_held(&mrp->lock)); > > + if (p) { > > + spin_lock(&br->lock); > > + p->state = BR_STATE_FORWARDING; > > + p->flags &= ~BR_MRP_AWARE; > > + br_mrp_port_switchdev_set_state(p, BR_STATE_FORWARDING); > > + rcu_assign_pointer(mrp->p_port, NULL); > > + spin_unlock(&br->lock); > > + } > > + > > + p = rcu_dereference_protected(mrp->s_port, lockdep_is_held(&mrp->lock)); > > + if (p) { > > + spin_lock(&br->lock); > > + p->state = BR_STATE_FORWARDING; > > + p->flags &= ~BR_MRP_AWARE; > > + br_mrp_port_switchdev_set_state(p, BR_STATE_FORWARDING); > > + rcu_assign_pointer(mrp->s_port, NULL); > > + spin_unlock(&br->lock); > > + } > > + > > + /* Destroy the ring */ > > + mrp->br = NULL; > > + > > + spin_unlock(&mrp->lock); > > + synchronize_rcu(); > > + > > + list_del_rcu(&mrp->list); > > + devm_kfree(&br->dev->dev, mrp); > > + > > + return 0; > > +} > > + > > +int br_mrp_set_port_state(struct net_bridge_port *p, > > + enum br_mrp_port_state_type state) > > +{ > > + spin_lock(&p->br->lock); > > + > > + if (state == BR_MRP_PORT_STATE_FORWARDING) > > + p->state = BR_STATE_FORWARDING; > > + else > > + p->state = BR_STATE_BLOCKING; > > + > > + br_mrp_port_switchdev_set_state(p, state); > > + > > + spin_unlock(&p->br->lock); > > + > > + return 0; > > +} > > + > > +int br_mrp_set_port_role(struct net_bridge_port *p, > > + u32 ring_id, enum br_mrp_port_role_type role) > > +{ > > + struct br_mrp *mrp = br_mrp_find_id(p->br, ring_id); > > + > > + if (!mrp) > > + return -EINVAL; > > + > > + spin_lock(&mrp->lock); > > + > > + if (role == BR_MRP_PORT_ROLE_PRIMARY) > > + rcu_assign_pointer(mrp->p_port, p); > > + if (role == BR_MRP_PORT_ROLE_SECONDARY) > > + rcu_assign_pointer(mrp->s_port, p); > > + > > + br_mrp_port_switchdev_set_role(p, role); > > + > > + spin_unlock(&mrp->lock); > > + synchronize_rcu(); > > Why do you need to synchronize here? Actually this is not needed. > > > + > > + return 0; > > +} > > + > > +int br_mrp_set_ring_state(struct net_bridge *br, u32 ring_id, > > + enum br_mrp_ring_state_type state) > > +{ > > + struct br_mrp *mrp = br_mrp_find_id(br, ring_id); > > + > > + if (!mrp) > > + return -EINVAL; > > + > > + if (mrp->ring_state == BR_MRP_RING_STATE_CLOSED && > > + state != BR_MRP_RING_STATE_CLOSED) > > + mrp->ring_transitions++; > > + > > + mrp->ring_state = state; > > + > > + br_mrp_switchdev_set_ring_state(mrp, state); > > + > > + return 0; > > +} > > + > > +int br_mrp_set_ring_role(struct net_bridge *br, u32 ring_id, > > + enum br_mrp_ring_role_type role) > > +{ > > + struct br_mrp *mrp = br_mrp_find_id(br, ring_id); > > + int err; > > + > > + if (!mrp) > > + return -EINVAL; > > + > > + mrp->ring_role = role; > > + > > + /* If there is an error just bailed out */ > > + err = br_mrp_switchdev_set_ring_role(mrp, role); > > + if (err && err != -EOPNOTSUPP) > > + return err; > > + > > + /* Now detect if the HW actually applied the role or not. If the HW > > + * applied the role it means that the SW will not to do those operations > > + * anymore. For example if the role ir MRM then the HW will notify the > > + * SW when ring is open, but if the is not pushed to the HW the SW will > > + * need to detect when the ring is open > > + */ > > + mrp->ring_role_offloaded = err == -EOPNOTSUPP ? 0 : 1; > > + > > + return 0; > > +} > > + > > +int br_mrp_start_test(struct net_bridge *br, u32 ring_id, u32 interval, > > + u8 max_miss, u32 period) > > +{ > > + struct br_mrp *mrp = br_mrp_find_id(br, ring_id); > > + > > + if (!mrp) > > + return -EINVAL; > > + > > + /* Try to push is to the HW and if it fails then continue to generate in > > + * SW and if that also fails then return error > > + */ > > + if (!br_mrp_switchdev_send_ring_test(mrp, interval, max_miss, period)) > > + return 0; > > + > > + mrp->test_interval = interval; > > + mrp->test_end = jiffies + usecs_to_jiffies(period); > > + mrp->test_max_miss = max_miss; > > + mrp->test_count_miss = 0; > > + queue_delayed_work(system_wq, &mrp->test_work, > > + usecs_to_jiffies(interval)); > > + > > + return 0; > > +} > > + > > +/* Process only MRP Test frame. All the other MRP frames are processed by > > + * userspace application > > + * note: already called with rcu_read_lock > > + */ > > +static void br_mrp_mrm_process(struct br_mrp *mrp, struct sk_buff *skb) > > +{ > > + struct br_mrp_tlv_hdr *hdr; > > + > > + hdr = (struct br_mrp_tlv_hdr *)(skb->data + sizeof(uint16_t)); > > + > > + if (hdr->type != BR_MRP_TLV_HEADER_RING_TEST) > > + return; > > + > > + mrp->test_count_miss = 0; > > + > > + br_mrp_port_open(rcu_dereference(mrp->p_port)->dev, false); > > + br_mrp_port_open(rcu_dereference(mrp->s_port)->dev, false); > > +} > > + > > +/* This will just forward the frame to the other mrp ring port(MRC role) or will > > + * not do anything. > > + * note: already called with rcu_read_lock > > + */ > > +static int br_mrp_rcv(struct net_bridge_port *p, > > + struct sk_buff *skb, struct net_device *dev) > > +{ > > + struct net_device *s_dev, *p_dev, *d_dev; > > + struct net_bridge *br; > > + struct sk_buff *nskb; > > + struct br_mrp *mrp; > > + > > + /* If port is disable don't accept any frames */ > > + if (p->state == BR_STATE_DISABLED) > > + return 0; > > + > > + br = p->br; > > + mrp = br_mrp_find_port(br, p); > > + if (unlikely(!mrp)) > > + return 0; > > + > > + /* If the role is MRM then don't forward the frames */ > > + if (mrp->ring_role == BR_MRP_RING_ROLE_MRM) { > > + br_mrp_mrm_process(mrp, skb); > > + return 1; > > + } > > + > > + nskb = skb_clone(skb, GFP_ATOMIC); > > + if (!nskb) > > + return 0; > > + > > + p_dev = rcu_dereference(mrp->p_port)->dev; > > + s_dev = rcu_dereference(mrp->s_port)->dev; > > + > > Not safe, could deref null. Will be fixed in the next patch series. > > > + if (p_dev == dev) > > + d_dev = s_dev; > > + else > > + d_dev = p_dev; > > + > > + nskb->dev = d_dev; > > + skb_push(nskb, ETH_HLEN); > > + dev_queue_xmit(nskb); > > + > > + return 1; > > +} > > + > > +int br_mrp_process(struct net_bridge_port *p, struct sk_buff *skb) > > +{ > > + /* If there is no MRP instance do normal forwarding */ > > + if (unlikely(!(p->flags & BR_MRP_AWARE))) > > Shouldn't this one be likely() ? Yes, this should be likely. > > > + goto out; > > + > > + if (unlikely(skb->protocol == htons(ETH_P_MRP))) > > + return br_mrp_rcv(p, skb, p->dev); > > + > > +out: > > + return 0; > > +} > > > [1] https://lwn.net/Articles/262464/ [2] https://www.kernel.org/doc/html/latest/RCU/listRCU.html -- /Horatiu