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06f877d613
In my first attempt to fix the lockdep splat, I forgot we could enter inet_csk_route_req() with a freshly allocated request socket, for which refcount has not yet been elevated, due to complex SLAB_TYPESAFE_BY_RCU rules. We either are in rcu_read_lock() section _or_ we own a refcount on the request. Correct RCU verb to use here is rcu_dereference_check(), although it is not possible to prove we actually own a reference on a shared refcount :/ In v2, I added ireq_opt_deref() helper and use in three places, to fix other possible splats. [ 49.844590] lockdep_rcu_suspicious+0xea/0xf3 [ 49.846487] inet_csk_route_req+0x53/0x14d [ 49.848334] tcp_v4_route_req+0xe/0x10 [ 49.850174] tcp_conn_request+0x31c/0x6a0 [ 49.851992] ? __lock_acquire+0x614/0x822 [ 49.854015] tcp_v4_conn_request+0x5a/0x79 [ 49.855957] ? tcp_v4_conn_request+0x5a/0x79 [ 49.858052] tcp_rcv_state_process+0x98/0xdcc [ 49.859990] ? sk_filter_trim_cap+0x2f6/0x307 [ 49.862085] tcp_v4_do_rcv+0xfc/0x145 [ 49.864055] ? tcp_v4_do_rcv+0xfc/0x145 [ 49.866173] tcp_v4_rcv+0x5ab/0xaf9 [ 49.868029] ip_local_deliver_finish+0x1af/0x2e7 [ 49.870064] ip_local_deliver+0x1b2/0x1c5 [ 49.871775] ? inet_del_offload+0x45/0x45 [ 49.873916] ip_rcv_finish+0x3f7/0x471 [ 49.875476] ip_rcv+0x3f1/0x42f [ 49.876991] ? ip_local_deliver_finish+0x2e7/0x2e7 [ 49.878791] __netif_receive_skb_core+0x6d3/0x950 [ 49.880701] ? process_backlog+0x7e/0x216 [ 49.882589] __netif_receive_skb+0x1d/0x5e [ 49.884122] process_backlog+0x10c/0x216 [ 49.885812] net_rx_action+0x147/0x3df Fixes: |
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| .. | ||
| ccids | ||
| ackvec.c | ||
| ackvec.h | ||
| ccid.c | ||
| ccid.h | ||
| dccp.h | ||
| diag.c | ||
| feat.c | ||
| feat.h | ||
| input.c | ||
| ipv4.c | ||
| ipv6.c | ||
| ipv6.h | ||
| Kconfig | ||
| Makefile | ||
| minisocks.c | ||
| options.c | ||
| output.c | ||
| probe.c | ||
| proto.c | ||
| qpolicy.c | ||
| sysctl.c | ||
| timer.c | ||