When use ovs-vsctl to delete vhostuserclient port while qemu destroy virtio,
there is a deadlock between OVS main thread and the vhost-events thread.
openvswitch is 2.14 and dpdk is 20.11
Main thread:
ofport_remove
-> netdev_unref
-> netdev_dpdk_vhost_destruct
-> rte_vhost_driver_unregister (If fdentry is busy, circle again
until the fdentry is not busy)
-> fdset_try_del (fdentry is busy now, return -1. Goto again)
vhost-nets thread:
fdset_event_dispatch (set fdentry to busy. When destroy_device fuction return
set the fdentry to no busy)
-> vhost_user_read_cb
-> vhost_user_msg_handler
-> vhost_user_get_vring_base
->destroy_device
-> ovsrcu_synchronize (Wait for other threads to quiesce)
The vhost-nets thread wait for main thread to quiesce, but the main thread now
is waiting for fdentry to no busy
and circle all the time.
Whether the ovsrcu_synchronize is necessary in destrory_device or the
rte_vhost_driver_unregister is correct in fdset_try_del ?
Best regards, Han Ding.
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