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net/mlx5e: Prevent encap offload when neigh update is running
The cited commit adds a compeletion to remove dependency on rtnl lock. But it causes a deadlock for multiple encapsulations: crash> bt ffff8aece8a64000 PID: 1514557 TASK: ffff8aece8a64000 CPU: 3 COMMAND: "tc" #0 [ffffa6d14183f368] __schedule at ffffffffb8ba7f45 jwrdegoede#1 [ffffa6d14183f3f8] schedule at ffffffffb8ba8418 jwrdegoede#2 [ffffa6d14183f418] schedule_preempt_disabled at ffffffffb8ba8898 jwrdegoede#3 [ffffa6d14183f428] __mutex_lock at ffffffffb8baa7f8 jwrdegoede#4 [ffffa6d14183f4d0] mutex_lock_nested at ffffffffb8baabeb jwrdegoede#5 [ffffa6d14183f4e0] mlx5e_attach_encap at ffffffffc0f48c17 [mlx5_core] jwrdegoede#6 [ffffa6d14183f628] mlx5e_tc_add_fdb_flow at ffffffffc0f39680 [mlx5_core] linux-sunxi#7 [ffffa6d14183f688] __mlx5e_add_fdb_flow at ffffffffc0f3b636 [mlx5_core] linux-sunxi#8 [ffffa6d14183f6f0] mlx5e_tc_add_flow at ffffffffc0f3bcdf [mlx5_core] linux-sunxi#9 [ffffa6d14183f728] mlx5e_configure_flower at ffffffffc0f3c1d1 [mlx5_core] linux-sunxi#10 [ffffa6d14183f790] mlx5e_rep_setup_tc_cls_flower at ffffffffc0f3d529 [mlx5_core] linux-sunxi#11 [ffffa6d14183f7a0] mlx5e_rep_setup_tc_cb at ffffffffc0f3d714 [mlx5_core] linux-sunxi#12 [ffffa6d14183f7b0] tc_setup_cb_add at ffffffffb8931bb8 linux-sunxi#13 [ffffa6d14183f810] fl_hw_replace_filter at ffffffffc0dae901 [cls_flower] linux-sunxi#14 [ffffa6d14183f8d8] fl_change at ffffffffc0db5c57 [cls_flower] linux-sunxi#15 [ffffa6d14183f970] tc_new_tfilter at ffffffffb8936047 linux-sunxi#16 [ffffa6d14183fac8] rtnetlink_rcv_msg at ffffffffb88c7c31 linux-sunxi#17 [ffffa6d14183fb50] netlink_rcv_skb at ffffffffb8942853 linux-sunxi#18 [ffffa6d14183fbc0] rtnetlink_rcv at ffffffffb88c1835 linux-sunxi#19 [ffffa6d14183fbd0] netlink_unicast at ffffffffb8941f27 linux-sunxi#20 [ffffa6d14183fc18] netlink_sendmsg at ffffffffb8942245 linux-sunxi#21 [ffffa6d14183fc98] sock_sendmsg at ffffffffb887d482 linux-sunxi#22 [ffffa6d14183fcb8] ____sys_sendmsg at ffffffffb887d81a linux-sunxi#23 [ffffa6d14183fd38] ___sys_sendmsg at ffffffffb88806e2 linux-sunxi#24 [ffffa6d14183fe90] __sys_sendmsg at ffffffffb88807a2 linux-sunxi#25 [ffffa6d14183ff28] __x64_sys_sendmsg at ffffffffb888080f linux-sunxi#26 [ffffa6d14183ff38] do_syscall_64 at ffffffffb8b9b6a8 linux-sunxi#27 [ffffa6d14183ff50] entry_SYSCALL_64_after_hwframe at ffffffffb8c0007c crash> bt 0xffff8aeb07544000 PID: 1110766 TASK: ffff8aeb07544000 CPU: 0 COMMAND: "kworker/u20:9" #0 [ffffa6d14e6b7bd8] __schedule at ffffffffb8ba7f45 jwrdegoede#1 [ffffa6d14e6b7c68] schedule at ffffffffb8ba8418 jwrdegoede#2 [ffffa6d14e6b7c88] schedule_timeout at ffffffffb8baef88 jwrdegoede#3 [ffffa6d14e6b7d10] wait_for_completion at ffffffffb8ba968b jwrdegoede#4 [ffffa6d14e6b7d60] mlx5e_take_all_encap_flows at ffffffffc0f47ec4 [mlx5_core] jwrdegoede#5 [ffffa6d14e6b7da0] mlx5e_rep_update_flows at ffffffffc0f3e734 [mlx5_core] jwrdegoede#6 [ffffa6d14e6b7df8] mlx5e_rep_neigh_update at ffffffffc0f400bb [mlx5_core] linux-sunxi#7 [ffffa6d14e6b7e50] process_one_work at ffffffffb80acc9c linux-sunxi#8 [ffffa6d14e6b7ed0] worker_thread at ffffffffb80ad012 linux-sunxi#9 [ffffa6d14e6b7f10] kthread at ffffffffb80b615d linux-sunxi#10 [ffffa6d14e6b7f50] ret_from_fork at ffffffffb8001b2f After the first encap is attached, flow will be added to encap entry's flows list. If neigh update is running at this time, the following encaps of the flow can't hold the encap_tbl_lock and sleep. If neigh update thread is waiting for that flow's init_done, deadlock happens. Fix it by holding lock outside of the for loop. If neigh update is running, prevent encap flows from offloading. Since the lock is held outside of the for loop, concurrent creation of encap entries is not allowed. So remove unnecessary wait_for_completion call for res_ready. Fixes: 95435ad ("net/mlx5e: Only access fully initialized flows in neigh update") Signed-off-by: Chris Mi <cmi@nvidia.com> Reviewed-by: Roi Dayan <roid@nvidia.com> Reviewed-by: Vlad Buslov <vladbu@nvidia.com> Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>
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