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[77.12.133.135]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-480021e7b3fsm25158434f8f.20.2026.08.09.05.14.58 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 09 Aug 2026 05:14:59 -0700 (PDT) From: Xin Xie To: netdev@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org Cc: davem@davemloft.net, edumazet@google.com, kuba@kernel.org, pabeni@redhat.com, horms@kernel.org, andrew+netdev@lunn.ch, shuah@kernel.org, kees@kernel.org, petr.wozniak@gmail.com, qingfang.deng@linux.dev, fmaurer@redhat.com, luka.gejak@linux.dev, bigeasy@linutronix.de, xiaoliang.yang_1@nxp.com, skhawaja@google.com, liuhangbin@gmail.com, stable@vger.kernel.org, sdf.kernel@gmail.com, Xin Xie , syzbot+fbf74291c3b7e753b481@syzkaller.appspotmail.com Subject: [PATCH 2/4] net: hsr: shrink seqnr_lock to sequence counter updates Date: Sun, 9 Aug 2026 14:14:52 +0200 Message-ID: <20260809121455.1745-3-xiexinet@gmail.com> X-Mailer: git-send-email 2.47.3 In-Reply-To: <20260809121455.1745-1-xiexinet@gmail.com> References: <20260809121455.1745-1-xiexinet@gmail.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Commit 06afd2c31d33 ("hsr: Synchronize sending frames to have always incremented outgoing seq nr.") and commit 430d67bdcb04 ("net: hsr: Use the seqnr lock for frames received via interlink port.") hold seqnr_lock across the whole forwarding path. Transmitting while holding the lock can create lock-dependency issues when HSR devices are stacked with other net devices, up to a real deadlock (see Reported-by/Closes). Since commit aae9d6b616b5 ("hsr: Implement more robust duplicate discard for HSR"), duplicate discard is order-independent (sparse bitmaps), so only the sequence counter updates need serialization. Limit seqnr_lock to the counter updates in handle_std_frame(); the master TX path (hsr_dev_xmit()) and the interlink RX path (hsr_handle_frame()) drop their outer lock, and the supervision frame builders release it right after their counter update. Concurrent forwarding may emit frames out of allocation order, which sparse-bitmap discard tolerates. The master/interlink tx statistics are no longer serialized; consistent per-cpu/per-queue statistics for all HSR paths are handled in a separate series. Fixes: 06afd2c31d33 ("hsr: Synchronize sending frames to have always incremented outgoing seq nr.") Fixes: 430d67bdcb04 ("net: hsr: Use the seqnr lock for frames received via interlink port.") Reported-by: syzbot+fbf74291c3b7e753b481@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=fbf74291c3b7e753b481 Cc: # aae9d6b616b5: hsr: Implement more robust duplicate discard for HSR Signed-off-by: Xin Xie --- net/hsr/hsr_device.c | 15 ++++----------- net/hsr/hsr_forward.c | 3 ++- net/hsr/hsr_slave.c | 11 +---------- 3 files changed, 7 insertions(+), 22 deletions(-) diff --git a/net/hsr/hsr_device.c b/net/hsr/hsr_device.c index 5555b71ab19b..3fd1762d8916 100644 --- a/net/hsr/hsr_device.c +++ b/net/hsr/hsr_device.c @@ -232,9 +232,7 @@ static netdev_tx_t hsr_dev_xmit(struct sk_buff *skb, struct net_device *dev) skb->dev = master->dev; skb_reset_mac_header(skb); skb_reset_mac_len(skb); - spin_lock_bh(&hsr->seqnr_lock); hsr_forward_skb(skb, master); - spin_unlock_bh(&hsr->seqnr_lock); } else { dev_core_stats_tx_dropped_inc(dev); dev_kfree_skb_any(skb); @@ -335,6 +333,7 @@ static void send_hsr_supervision_frame(struct hsr_port *port, hsr_stag->sequence_nr = htons(hsr->sequence_nr); hsr->sequence_nr++; } + spin_unlock_bh(&hsr->seqnr_lock); hsr_stag->tlv.HSR_TLV_type = type; /* HSRv0 has 6 unused bytes after the MAC */ @@ -356,14 +355,10 @@ static void send_hsr_supervision_frame(struct hsr_port *port, ether_addr_copy(hsr_sp->macaddress_A, hsr->macaddress_redbox); } - if (skb_put_padto(skb, ETH_ZLEN)) { - spin_unlock_bh(&hsr->seqnr_lock); + if (skb_put_padto(skb, ETH_ZLEN)) return; - } hsr_forward_skb(skb, port); - spin_unlock_bh(&hsr->seqnr_lock); - return; } static void send_prp_supervision_frame(struct hsr_port *master, @@ -390,6 +385,7 @@ static void send_prp_supervision_frame(struct hsr_port *master, spin_lock_bh(&hsr->seqnr_lock); hsr_stag->sequence_nr = htons(hsr->sup_sequence_nr); hsr->sup_sequence_nr++; + spin_unlock_bh(&hsr->seqnr_lock); hsr_stag->tlv.HSR_TLV_type = PRP_TLV_LIFE_CHECK_DD; hsr_stag->tlv.HSR_TLV_length = sizeof(struct hsr_sup_payload); @@ -397,13 +393,10 @@ static void send_prp_supervision_frame(struct hsr_port *master, hsr_sp = skb_put(skb, sizeof(struct hsr_sup_payload)); ether_addr_copy(hsr_sp->macaddress_A, master->dev->dev_addr); - if (skb_put_padto(skb, ETH_ZLEN)) { - spin_unlock_bh(&hsr->seqnr_lock); + if (skb_put_padto(skb, ETH_ZLEN)) return; - } hsr_forward_skb(skb, master); - spin_unlock_bh(&hsr->seqnr_lock); } /* Announce (supervision frame) timer function diff --git a/net/hsr/hsr_forward.c b/net/hsr/hsr_forward.c index 0774981a65c1..8e4158a9b57c 100644 --- a/net/hsr/hsr_forward.c +++ b/net/hsr/hsr_forward.c @@ -621,9 +621,10 @@ static void handle_std_frame(struct sk_buff *skb, if (port->type == HSR_PT_MASTER || port->type == HSR_PT_INTERLINK) { /* Sequence nr for the master/interlink node */ - lockdep_assert_held(&hsr->seqnr_lock); + spin_lock_bh(&hsr->seqnr_lock); frame->sequence_nr = hsr->sequence_nr; hsr->sequence_nr++; + spin_unlock_bh(&hsr->seqnr_lock); } } diff --git a/net/hsr/hsr_slave.c b/net/hsr/hsr_slave.c index bb2182a169a3..8b96eafe15b3 100644 --- a/net/hsr/hsr_slave.c +++ b/net/hsr/hsr_slave.c @@ -73,16 +73,7 @@ static rx_handler_result_t hsr_handle_frame(struct sk_buff **pskb) } skb_reset_mac_len(skb); - /* Only the frames received over the interlink port will assign a - * sequence number and require synchronisation vs other sender. - */ - if (port->type == HSR_PT_INTERLINK) { - spin_lock_bh(&hsr->seqnr_lock); - hsr_forward_skb(skb, port); - spin_unlock_bh(&hsr->seqnr_lock); - } else { - hsr_forward_skb(skb, port); - } + hsr_forward_skb(skb, port); finish_consume: return RX_HANDLER_CONSUMED; -- 2.43.0