[PATCH v2] can: statistics: add missing atomic access in hot path

[PATCH v2] can: statistics: add missing atomic access in hot path

[Oliver Hartkopp]

Commit 80b5f90158d1 ("can: statistics: use atomic access in hot path")
fixed a KCSAN issue in can_receive() but missed to convert the 'matches'
variable used in can_rcv_filter().

Fixes: 80b5f90158d1 ("can: statistics: use atomic access in hot path")
Signed-off-by: Oliver Hartkopp <socketcan@hartkopp.net>
---
 net/can/af_can.c | 4 ++--
 net/can/af_can.h | 2 +-
 net/can/proc.c   | 3 ++-
 3 files changed, 5 insertions(+), 4 deletions(-)

diff --git a/net/can/af_can.c b/net/can/af_can.c
index f70e2ba0aadc..7bc86b176b4d 100644
--- a/net/can/af_can.c
+++ b/net/can/af_can.c
@@ -467,11 +467,11 @@ int can_rx_register(struct net *net, struct net_device *dev, canid_t can_id,
 	dev_rcv_lists = can_dev_rcv_lists_find(net, dev);
 	rcv_list = can_rcv_list_find(&can_id, &mask, dev_rcv_lists);
 
 	rcv->can_id = can_id;
 	rcv->mask = mask;
-	rcv->matches = 0;
+	atomic_long_set(&rcv->matches, 0);
 	rcv->func = func;
 	rcv->data = data;
 	rcv->ident = ident;
 	rcv->sk = sk;
 
@@ -571,11 +571,11 @@ void can_rx_unregister(struct net *net, struct net_device *dev, canid_t can_id,
 EXPORT_SYMBOL(can_rx_unregister);
 
 static inline void deliver(struct sk_buff *skb, struct receiver *rcv)
 {
 	rcv->func(skb, rcv->data);
-	rcv->matches++;
+	atomic_long_inc(&rcv->matches);
 }
 
 static int can_rcv_filter(struct can_dev_rcv_lists *dev_rcv_lists, struct sk_buff *skb)
 {
 	struct receiver *rcv;
diff --git a/net/can/af_can.h b/net/can/af_can.h
index 22f3352c77fe..87887014f562 100644
--- a/net/can/af_can.h
+++ b/net/can/af_can.h
@@ -50,11 +50,11 @@
 
 struct receiver {
 	struct hlist_node list;
 	canid_t can_id;
 	canid_t mask;
-	unsigned long matches;
+	atomic_long_t matches;
 	void (*func)(struct sk_buff *skb, void *data);
 	void *data;
 	char *ident;
 	struct sock *sk;
 	struct rcu_head rcu;
diff --git a/net/can/proc.c b/net/can/proc.c
index 0938bf7dd646..de4d05ae3459 100644
--- a/net/can/proc.c
+++ b/net/can/proc.c
@@ -194,11 +194,12 @@ static void can_print_rcvlist(struct seq_file *m, struct hlist_head *rx_list,
 		char *fmt = (r->can_id & CAN_EFF_FLAG)?
 			"   %-5s  %08x  %08x  %pK  %pK  %8ld  %s\n" :
 			"   %-5s     %03x    %08x  %pK  %pK  %8ld  %s\n";
 
 		seq_printf(m, fmt, DNAME(dev), r->can_id, r->mask,
-				r->func, r->data, r->matches, r->ident);
+			   r->func, r->data, atomic_long_read(&r->matches),
+			   r->ident);
 	}
 }
 
 static void can_print_recv_banner(struct seq_file *m)
 {
-- 
2.51.0

Re: [PATCH v2] can: statistics: add missing atomic access in hot path

[Marc Kleine-Budde]

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On 18.03.2026 18:34:13, Oliver Hartkopp wrote:
> Commit 80b5f90158d1 ("can: statistics: use atomic access in hot path")
> fixed a KCSAN issue in can_receive() but missed to convert the 'matches'
> variable used in can_rcv_filter().
>
> Fixes: 80b5f90158d1 ("can: statistics: use atomic access in hot path")
> Signed-off-by: Oliver Hartkopp <socketcan@hartkopp.net>

Added to linux-can.

regards,
Marc

-- 
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