seqnr_lock currently covers the whole forwarding path although only the
sequence counters need serialization. Limit it to the counter updates.

The old lock also serialized the tx statistics; use DEV_STATS_INC() and
DEV_STATS_ADD() for their now-concurrent updates. Concurrently forwarded
frames may be emitted out of allocation order, which sparse-bitmap
duplicate discard tolerates.

The GSO segmentation patch depends on this shorter critical section. Apply
both only to 7.0 and newer, where sparse-bitmap duplicate discard is
present; older trees require an adapted backport.

Cc: <[email protected]> # 7.0.x
Signed-off-by: Xin Xie <[email protected]>
---
 net/hsr/hsr_device.c  | 15 ++++-----------
 net/hsr/hsr_forward.c |  9 +++++----
 net/hsr/hsr_slave.c   | 11 +----------
 3 files changed, 10 insertions(+), 25 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..87cd72a1dc65 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);
        }
 }
 
@@ -746,8 +747,8 @@ void hsr_forward_skb(struct sk_buff *skb, struct hsr_port 
*port)
         * So check and increment stats for master port only here.
         */
        if (port->type == HSR_PT_MASTER || port->type == HSR_PT_INTERLINK) {
-               port->dev->stats.tx_packets++;
-               port->dev->stats.tx_bytes += skb->len;
+               DEV_STATS_INC(port->dev, tx_packets);
+               DEV_STATS_ADD(port->dev, tx_bytes, skb->len);
        }
 
        kfree_skb(frame.skb_hsr);
@@ -757,6 +758,6 @@ void hsr_forward_skb(struct sk_buff *skb, struct hsr_port 
*port)
 
 out_drop:
        rcu_read_unlock();
-       port->dev->stats.tx_dropped++;
+       DEV_STATS_INC(port->dev, tx_dropped);
        kfree_skb(skb);
 }
diff --git a/net/hsr/hsr_slave.c b/net/hsr/hsr_slave.c
index 3cae70754bc4..aa2154b19c0b 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


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