vtnet: Pre-allocate debugnet data immediately
Don't wait until the vtnet_debugnet_init() call happens, because at that
point we might already have allocated something from
vtnet_tx_header_zone.
Some systems showed this panic:
vtnet0: link state changed to UP panic: keg vtnet_tx_hdr initialization after use. cpuid = 5 time = 1578427700 KDB: stack backtrace: db_trace_self_wrapper() at db_trace_self_wrapper+0x2b/frame 0xfffffe004db427f0 vpanic() at vpanic+0x17e/frame 0xfffffe004db42850 panic() at panic+0x43/frame 0xfffffe004db428b0 uma_zone_reserve() at uma_zone_reserve+0xf6/frame 0xfffffe004db428f0 vtnet_debugnet_init() at vtnet_debugnet_init+0x77/frame 0xfffffe004db42930 debugnet_any_ifnet_update() at debugnet_any_ifnet_update+0x42/frame 0xfffffe004db42980 do_link_state_change() at do_link_state_change+0x1b3/frame 0xfffffe004db429d0 taskqueue_run_locked() at taskqueue_run_locked+0x178/frame 0xfffffe004db42a30 taskqueue_run() at taskqueue_run+0x4d/frame 0xfffffe004db42a50 ithread_loop() at ithread_loop+0x1d6/frame 0xfffffe004db42ab0 fork_exit() at fork_exit+0x80/frame 0xfffffe004db42af0 fork_trampoline() at fork_trampoline+0xe/frame 0xfffffe004db42af0 --- trap 0, rip = 0, rsp = 0, rbp = 0 --- KDB: enter: panic [ thread pid 12 tid 100011 ] Stopped at kdb_enter+0x37: movq $0,0x1084eb6(%rip) db>
Reviewed by: cem, markj
Differential Revision: https://reviews.freebsd.org/D23073