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can: gw: syncronize rcu operations before removing gw job entry

PATCH In review Oliver Hartkopp 2 participants 2 messages Jun 18, 2021 – Jun 19, 2021

Subsystems (2)
CAN network drivers CAN network layer
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Oliver Hartkopp

author maintainer
#0 lore raw

PATCH 1/1 can: gw: syncronize rcu operations before removing gw job entry

can_can_gw_rcv() is called under RCU protection, so after calling can_rx_unregister, we may call synchronize_rcu in order to wait for any RCU read-side critical sections to finish before removing the kmem_cache entry with the referenced gw job entry.

Signed-off-by Oliver Hartkopp <[email protected]>
---
 net/can/gw.c | 3 +++
 1 file changed, 3 insertions(+)
net/can/gw.c +3 -0
index ba4124805602..d8861e862f15 100644
@@ -594,10 +594,11 @@ static int cgw_notifier(struct notifier_block *nb,
 
 		hlist_for_each_entry_safe(gwj, nx, &net->can.cgw_list, list) {
 			if (gwj->src.dev == dev || gwj->dst.dev == dev) {
 				hlist_del(&gwj->list);
 				cgw_unregister_filter(net, gwj);
+				synchronize_rcu();
 				kmem_cache_free(cgw_cache, gwj);
 			}
 		}
 	}
 

@@ -1152,10 +1153,11 @@ static void cgw_remove_all_jobs(struct net *net)
 	ASSERT_RTNL();
 
 	hlist_for_each_entry_safe(gwj, nx, &net->can.cgw_list, list) {
 		hlist_del(&gwj->list);
 		cgw_unregister_filter(net, gwj);
+		synchronize_rcu();
 		kmem_cache_free(cgw_cache, gwj);
 	}
 }
 
 static int cgw_remove_job(struct sk_buff *skb, struct nlmsghdr *nlh,

@@ -1220,10 +1222,11 @@ static int cgw_remove_job(struct sk_buff *skb, struct nlmsghdr *nlh,
 		if (memcmp(&gwj->ccgw, &ccgw, sizeof(ccgw)))
 			continue;
 
 		hlist_del(&gwj->list);
 		cgw_unregister_filter(net, gwj);
+		synchronize_rcu();
 		kmem_cache_free(cgw_cache, gwj);
 		err = 0;
 		break;
 	}
Signature · 1 line
2.30.2
maintainer
#1 lore raw
Quoted 6 lines · Oliver Hartkopp

can_can_gw_rcv() is called under RCU protection, so after calling can_rx_unregister, we may call synchronize_rcu in order to wait for any RCU read-side critical sections to finish before removing the kmem_cache entry with the referenced gw job entry.

Signed-off-by Oliver Hartkopp <[email protected]>

Applied to linux-can/testing.

Thanks,
Marc

Signature · 4 lines
Pengutronix e.K.                 | Marc Kleine-Budde           |
Embedded Linux                   | https://www.pengutronix.de  |
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