RE: [PATCH 4.14] tcp: fix tcp_rtx_queue_tail in case of empty retransmit queue

[maowenan]

[<ffffff90094930dc>] skb_peek_tail include/linux/skbuff.h:1516 [inline]
[<ffffff90094930dc>] tcp_write_queue_tail include/net/tcp.h:1478 [inline]
[<ffffff90094930dc>] tcp_rtx_queue_tail include/net/tcp.h:1543 [inline]
[<ffffff90094930dc>] tcp_fragment+0xc64/0xce8 net/ipv4/tcp_output.c:1175
[<ffffff90094a37f0>] tcp_write_wakeup+0x3f8/0x4a0 net/ipv4/tcp_output.c:3496
[<ffffff90094a38d0>] tcp_send_probe0+0x38/0x2d8 net/ipv4/tcp_output.c:3523
[<ffffff90094a75a0>] tcp_probe_timer net/ipv4/tcp_timer.c:343 [inline]
[<ffffff90094a75a0>] tcp_write_timer_handler+0x640/0x720 net/ipv4/tcp_timer.c:548
[<ffffff90094a76f8>] tcp_write_timer+0x78/0x1d0 net/ipv4/tcp_timer.c:562
[<ffffff90082610b0>] call_timer_fn.isra.1+0x58/0x180 kernel/time/timer.c:1144
[<ffffff90082616ec>] __run_timers kernel/time/timer.c:1218 [inline]
[<ffffff90082616ec>] run_timer_softirq+0x514/0x848 kernel/time/timer.c:1401
[<ffffff9008141a28>] __do_softirq+0x340/0x878 kernel/softirq.c:273
[<ffffff9008142890>] do_softirq_own_stack include/linux/interrupt.h:498 [inline]
[<ffffff9008142890>] invoke_softirq kernel/softirq.c:357 [inline]
[<ffffff9008142890>] irq_exit+0x170/0x370 kernel/softirq.c:391
[<ffffff900821d550>] __handle_domain_irq+0x100/0x1c0 kernel/irq/irqdesc.c:459
[<ffffff90080914a0>] handle_domain_irq include/linux/irqdesc.h:168 [inline]
[<ffffff90080914a0>] gic_handle_irq+0xd0/0x1f0 drivers/irqchip/irq-gic.c:377