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nfp: flower-ct: remove callback delete deadlock
The current location of the callback delete can lead to a race
condition where deleting the callback requires a write_lock on
the nf_table, but at the same time another thread from netfilter
could have taken a read lock on the table before trying to offload.
Since the driver is taking a rtnl_lock this can lead into a deadlock
situation, where the netfilter offload will wait for the cls_flower
rtnl_lock to be released, but this cannot happen since this is
waiting for the nf_table read_lock to be released before it can
delete the callback.
Solve this by completely removing the nf_flow_table_offload_del_cb
call, as this will now be cleaned up by act_ct itself when cleaning
up the specific nf_table.
Fixes: 62268e7814
("nfp: flower-ct: add nft callback stubs")
Signed-off-by: Louis Peens <louis.peens@corigine.com>
Signed-off-by: Yinjun Zhang <yinjun.zhang@corigine.com>
Signed-off-by: Simon Horman <simon.horman@corigine.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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1 changed files with 0 additions and 13 deletions
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@ -1141,20 +1141,7 @@ int nfp_fl_ct_del_flow(struct nfp_fl_ct_map_entry *ct_map_ent)
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nfp_fl_ct_clean_flow_entry(ct_entry);
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kfree(ct_map_ent);
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/* If this is the last pre_ct_rule it means that it is
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* very likely that the nft table will be cleaned up next,
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* as this happens on the removal of the last act_ct flow.
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* However we cannot deregister the callback on the removal
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* of the last nft flow as this runs into a deadlock situation.
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* So deregister the callback on removal of the last pre_ct flow
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* and remove any remaining nft flow entries. We also cannot
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* save this state and delete the callback later since the
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* nft table would already have been freed at that time.
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*/
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if (!zt->pre_ct_count) {
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nf_flow_table_offload_del_cb(zt->nft,
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nfp_fl_ct_handle_nft_flow,
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zt);
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zt->nft = NULL;
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nfp_fl_ct_clean_nft_entries(zt);
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}
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