There is a couple of places from which we can arrive to ndo_setup_tc
with TC_SETUP_BLOCK/TC_SETUP_FT:
- netlink
- netlink notifier
- netdev notifier
Locking netdev too deep in this call chain seems to be problematic
(especially assuming some/all of the call_netdevice_notifiers
NETDEV_UNREGISTER) might soon be running with the instance lock).
Revert to lockless ndo_setup_tc for TC_SETUP_BLOCK/TC_SETUP_FT. NFT
framework already takes care of most of the locking. Document
the assumptions.
ndo_setup_tc TC_SETUP_BLOCK
nft_block_offload_cmd
nft_chain_offload_cmd
nft_flow_block_chain
nft_flow_offload_chain
nft_flow_rule_offload_abort
nft_flow_rule_offload_commit
nft_flow_rule_offload_commit
nf_tables_commit
nfnetlink_rcv_batch
nfnetlink_rcv_skb_batch
nfnetlink_rcv
nft_offload_netdev_event
NETDEV_UNREGISTER notifier
ndo_setup_tc TC_SETUP_FT
nf_flow_table_offload_cmd
nf_flow_table_offload_setup
nft_unregister_flowtable_hook
nft_register_flowtable_net_hooks
nft_flowtable_update
nf_tables_newflowtable
nfnetlink_rcv_batch (.call NFNL_CB_BATCH)
nft_flowtable_update
nf_tables_newflowtable
nft_flowtable_event
nf_tables_flowtable_event
NETDEV_UNREGISTER notifier
__nft_unregister_flowtable_net_hooks
nft_unregister_flowtable_net_hooks
nf_tables_commit
nfnetlink_rcv_batch (.call NFNL_CB_BATCH)
__nf_tables_abort
nf_tables_abort
nfnetlink_rcv_batch
__nft_release_hook
__nft_release_hooks
nf_tables_pre_exit_net -> module unload
nft_rcv_nl_event
netlink_register_notifier (oh boy)
nft_register_flowtable_net_hooks
nft_flowtable_update
nf_tables_newflowtable
nf_tables_newflowtable
Fixes: c4f0f30b424e ("net: hold netdev instance lock during nft ndo_setup_tc")
Signed-off-by: Stanislav Fomichev <sdf@xxxxxxxxxxx>
---
Documentation/networking/netdevices.rst | 6 ++++++
include/linux/netdevice.h | 2 --
net/core/dev.c | 19 -------------------
net/netfilter/nf_flow_table_offload.c | 2 +-
net/netfilter/nf_tables_offload.c | 2 +-
5 files changed, 8 insertions(+), 23 deletions(-)
diff --git a/Documentation/networking/netdevices.rst b/Documentation/networking/netdevices.rst
index d235a7364893..ebb868f50ac2 100644
--- a/Documentation/networking/netdevices.rst
+++ b/Documentation/networking/netdevices.rst
@@ -290,6 +290,12 @@ struct net_device synchronization rules
Synchronization: netif_addr_lock spinlock.
Context: BHs disabled
+ndo_setup_tc:
+ ``TC_SETUP_BLOCK`` and ``TC_SETUP_FT`` are running under NFT locks
+ (i.e. no ``rtnl_lock`` and no device instance lock). The rest of
+ ``tc_setup_type`` types run under netdev instance lock if the driver
+ implements queue management or shaper API.
+
Most ndo callbacks not specified in the list above are running
under ``rtnl_lock``. In addition, netdev instance lock is taken as well if
the driver implements queue management or shaper API.
diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index d206c9592b60..87fd3b1f2b99 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -3395,8 +3395,6 @@ int dev_open(struct net_device *dev, struct netlink_ext_ack *extack);
void netif_close(struct net_device *dev);
void dev_close(struct net_device *dev);
void dev_close_many(struct list_head *head, bool unlink);
-int dev_setup_tc(struct net_device *dev, enum tc_setup_type type,
- void *type_data);
void netif_disable_lro(struct net_device *dev);
void dev_disable_lro(struct net_device *dev);
int dev_loopback_xmit(struct net *net, struct sock *sk, struct sk_buff *newskb);
diff --git a/net/core/dev.c b/net/core/dev.c
index a0f75a1d1f5a..8b3603b764a7 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -1760,25 +1760,6 @@ void netif_close(struct net_device *dev)
}
}
-int dev_setup_tc(struct net_device *dev, enum tc_setup_type type,
- void *type_data)
-{
- const struct net_device_ops *ops = dev->netdev_ops;
- int ret;
-
- ASSERT_RTNL();
-
- if (!ops->ndo_setup_tc)
- return -EOPNOTSUPP;
-
- netdev_lock_ops(dev);
- ret = ops->ndo_setup_tc(dev, type, type_data);
- netdev_unlock_ops(dev);
-
- return ret;
-}
-EXPORT_SYMBOL(dev_setup_tc);
-
void netif_disable_lro(struct net_device *dev)
{
struct net_device *lower_dev;
diff --git a/net/netfilter/nf_flow_table_offload.c b/net/netfilter/nf_flow_table_offload.c
index 0ec4abded10d..e06bc36f49fe 100644
--- a/net/netfilter/nf_flow_table_offload.c
+++ b/net/netfilter/nf_flow_table_offload.c
@@ -1175,7 +1175,7 @@ static int nf_flow_table_offload_cmd(struct flow_block_offload *bo,
nf_flow_table_block_offload_init(bo, dev_net(dev), cmd, flowtable,
extack);
down_write(&flowtable->flow_block_lock);
- err = dev_setup_tc(dev, TC_SETUP_FT, bo);
+ err = dev->netdev_ops->ndo_setup_tc(dev, TC_SETUP_FT, bo);
up_write(&flowtable->flow_block_lock);
if (err < 0)
return err;
diff --git a/net/netfilter/nf_tables_offload.c b/net/netfilter/nf_tables_offload.c
index b761899c143c..64675f1c7f29 100644
--- a/net/netfilter/nf_tables_offload.c
+++ b/net/netfilter/nf_tables_offload.c
@@ -390,7 +390,7 @@ static int nft_block_offload_cmd(struct nft_base_chain *chain,
nft_flow_block_offload_init(&bo, dev_net(dev), cmd, chain, &extack);
- err = dev_setup_tc(dev, TC_SETUP_BLOCK, &bo);
+ err = dev->netdev_ops->ndo_setup_tc(dev, TC_SETUP_BLOCK, &bo);
if (err < 0)
return err;
--
2.48.1
