Re: [PATCH net] af_packet: set defaule value for tmo

[David Miller]

From: Mao Wenan <maowenan@xxxxxxxxxx>
Date: Mon, 9 Dec 2019 21:31:25 +0800

> There is softlockup when using TPACKET_V3:
> ...
> NMI watchdog: BUG: soft lockup - CPU#2 stuck for 60010ms!
> (__irq_svc) from [<c0558a0c>] (_raw_spin_unlock_irqrestore+0x44/0x54)
> (_raw_spin_unlock_irqrestore) from [<c027b7e8>] (mod_timer+0x210/0x25c)
> (mod_timer) from [<c0549c30>]
> (prb_retire_rx_blk_timer_expired+0x68/0x11c)
> (prb_retire_rx_blk_timer_expired) from [<c027a7ac>]
> (call_timer_fn+0x90/0x17c)
> (call_timer_fn) from [<c027ab6c>] (run_timer_softirq+0x2d4/0x2fc)
> (run_timer_softirq) from [<c021eaf4>] (__do_softirq+0x218/0x318)
> (__do_softirq) from [<c021eea0>] (irq_exit+0x88/0xac)
> (irq_exit) from [<c0240130>] (msa_irq_exit+0x11c/0x1d4)
> (msa_irq_exit) from [<c0209cf0>] (handle_IPI+0x650/0x7f4)
> (handle_IPI) from [<c02015bc>] (gic_handle_irq+0x108/0x118)
> (gic_handle_irq) from [<c0558ee4>] (__irq_usr+0x44/0x5c)
> ...
> 
> If __ethtool_get_link_ksettings() is failed in
> prb_calc_retire_blk_tmo(), msec and tmo will be zero, so tov_in_jiffies
> is zero and the timer expire for retire_blk_timer is turn to
> mod_timer(&pkc->retire_blk_timer, jiffies + 0),
> which will trigger cpu usage of softirq is 100%.
> 
> Fixes: f6fb8f100b80 ("af-packet: TPACKET_V3 flexible buffer implementation.")
> Tested-by: Xiao Jiangfeng <xiaojiangfeng@xxxxxxxxxx>
> Signed-off-by: Mao Wenan <maowenan@xxxxxxxxxx>

Applied, thanks.