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[109.236.14.10]) by smtp.gmail.com with ESMTPSA id 98e67ed59e1d1-3a8987b09e2sm4456582a91.2.2026.10.07.04.58.45 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 07 Oct 2026 04:58:50 -0700 (PDT) Sender: Yuyang Huang From: Yuyang Huang To: Yuyang Huang Cc: Ajay Singh , Aleksandr Loktionov , Andrew Lunn , Claudiu Beznea , "David S. Miller" , David Ahern , Donald Hunter , Eric Dumazet , Ido Schimmel , Jacob Keller , Jakub Kicinski , Johannes Berg , Kees Cook , Kory Maincent , Kuniyuki Iwashima , Nicolas Dichtel , Nikolaos Gkarlis , Paolo Abeni , Sabrina Dubroca , Shuah Khan , Simon Horman , Stanislav Fomichev , Vadim Fedorenko , Willem de Bruijn , linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-wireless@vger.kernel.org, netdev@vger.kernel.org Subject: [PATCH net-next v10 3/6] net: add a generation counter for dev->mc changes Date: Wed, 7 Oct 2026 20:58:18 +0900 Message-ID: <20261007115821.11332-4-sigefriedhyy@gmail.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20261007115821.11332-1-sigefriedhyy@gmail.com> References: <20261007115821.11332-1-sigefriedhyy@gmail.com> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit A multi-part RTM_GETMULTICAST dump of dev->mc resumes by position, so entries added or removed between two dump rounds can be skipped or repeated. The IPv4 and IPv6 dumps report that with NLM_F_DUMP_INTR by stamping cb->seq from a per netns generation counter combined with dev_base_seq, see inet_base_seq(). Add the equivalent for the device multicast lists: a per netns counter bumped whenever an entry is added to or removed from any dev->mc. The list helpers do not know which device a list belongs to, so give netdev_hw_addr_list an mc_dev pointer, set for dev->mc only, and bump the counter of dev_net(mc_dev) from the count helpers. That covers the dev_mc_* helpers, both lists of a sync, the hardware sync helpers drivers call from their rx mode callbacks or their own workers and the reconciliation after an asynchronous rx mode update. It is atomic since the writers only hold the address lock of their own device. Used by the following patch for the AF_PACKET multicast dump. Signed-off-by: Yuyang Huang --- include/linux/netdevice.h | 3 +++ include/net/net_namespace.h | 1 + net/core/dev_addr_lists.c | 15 +++++++++++++++ 3 files changed, 19 insertions(+) diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h index 3d9e3a70ca5c9..6c837ea34748e 100644 --- a/include/linux/netdevice.h +++ b/include/linux/netdevice.h @@ -259,6 +259,9 @@ struct netdev_hw_addr_list { /* Auxiliary tree for faster lookup on addition and deletion */ struct rb_root tree; + + /* Set for dev->mc only, the device the list belongs to */ + struct net_device *mc_dev; }; #define netdev_hw_addr_list_count(l) ((l)->_count) diff --git a/include/net/net_namespace.h b/include/net/net_namespace.h index 46b4c67e2966f..c29a22ca178fa 100644 --- a/include/net/net_namespace.h +++ b/include/net/net_namespace.h @@ -71,6 +71,7 @@ struct net { spinlock_t rules_mod_lock; unsigned int dev_base_seq; /* protected by rtnl_mutex */ + atomic_t dev_mc_genid; /* dev->mc membership changes */ u32 ifindex; spinlock_t nsid_lock; diff --git a/net/core/dev_addr_lists.c b/net/core/dev_addr_lists.c index d615192d1c3b1..3ab053cbf8b99 100644 --- a/net/core/dev_addr_lists.c +++ b/net/core/dev_addr_lists.c @@ -16,9 +16,19 @@ #include "dev.h" +/* RTM_GETMULTICAST dumps use the netns generation counter to detect + * changes of dev->mc between dump rounds. + */ +static void __hw_addr_changed(struct netdev_hw_addr_list *list) +{ + if (list->mc_dev) + atomic_inc(&dev_net(list->mc_dev)->dev_mc_genid); +} + static void __hw_addr_count_add(struct netdev_hw_addr_list *list, int value) { list->_count += value; + __hw_addr_changed(list); } static void __hw_addr_count_inc(struct netdev_hw_addr_list *list) @@ -33,7 +43,10 @@ static void __hw_addr_count_dec(struct netdev_hw_addr_list *list) static void __hw_addr_count_reset(struct netdev_hw_addr_list *list) { + if (!list->_count) + return; list->_count = 0; + __hw_addr_changed(list); } /* @@ -521,6 +534,7 @@ void __hw_addr_init(struct netdev_hw_addr_list *list) INIT_LIST_HEAD(&list->list); list->_count = 0; list->tree = RB_ROOT; + list->mc_dev = NULL; } EXPORT_SYMBOL(__hw_addr_init); @@ -1197,6 +1211,7 @@ EXPORT_SYMBOL(dev_mc_flush); void dev_mc_init(struct net_device *dev) { __hw_addr_init(&dev->mc); + dev->mc.mc_dev = dev; } EXPORT_SYMBOL(dev_mc_init); -- 2.43.0