NCSI warning in ncsi_start_channel_monitor

[shenki]

From https://github.com/openbmc/openbmc/issues/1064

VERSION_ID="v1.99.1-82-gbfd622e-dirty"

4.7.10-f26558191540830589fe03932d05577957670b8d

palmetto login: ftgmac100 1e660000.ethernet eth0: NCSI interface up
random: nonblocking pool is initialized
ftgmac100 1e660000.ethernet eth0: NCSI interface down
ftgmac100 1e660000.ethernet eth0: NCSI interface up
ftgmac100 1e660000.ethernet eth0: NCSI interface down
------------[ cut here ]------------
WARNING: CPU: 0 PID: 411 at /var/lib/jenkins/workspace/openbmc-build/distro/ubuntu/target/palmetto/openbmc/build/tmp/work-shared/palmetto/kernel-source/net/ncsi/ncsi-manage.c:240 ncsi_start_channel_monitor+0x44/0x7c
CPU: 0 PID: 411 Comm: kworker/0:3 Not tainted 4.7.10-f26558191540830589fe03932d05577957670b8d #1
Hardware name: ASpeed SoC
Workqueue: events ncsi_dev_work
[<c0106cbc>] (unwind_backtrace) from [<c0104f04>] (show_stack+0x10/0x14)
[<c0104f04>] (show_stack) from [<c010eef8>] (__warn+0xc4/0xf0)
[<c010eef8>] (__warn) from [<c010f018>] (warn_slowpath_null+0x1c/0x24)
[<c010f018>] (warn_slowpath_null) from [<c03e1d10>] (ncsi_start_channel_monitor+0x44/0x7c)
[<c03e1d10>] (ncsi_start_channel_monitor) from [<c03e29c4>] (ncsi_configure_channel+0x27c/0x2dc)
[<c03e29c4>] (ncsi_configure_channel) from [<c03e31d0>] (ncsi_dev_work+0x39c/0x3e8)
[<c03e31d0>] (ncsi_dev_work) from [<c0120288>] (process_one_work+0x1b8/0x2fc)
[<c0120288>] (process_one_work) from [<c01206bc>] (worker_thread+0x2c0/0x3f8)
[<c01206bc>] (worker_thread) from [<c0124b10>] (kthread+0xd0/0xe8)
[<c0124b10>] (kthread) from [<c0102250>] (ret_from_fork+0x14/0x24)
---[ end trace 110cccf2b038c44d ]---
ftgmac100 1e660000.ethernet eth0: NCSI interface down

void ncsi_start_channel_monitor(struct ncsi_channel *nc)
{
        unsigned long flags;

        spin_lock_irqsave(&nc->lock, flags);
        WARN_ON_ONCE(nc->monitor.enabled);
        nc->monitor.enabled = true;
        nc->monitor.state = NCSI_CHANNEL_MONITOR_START;
        spin_unlock_irqrestore(&nc->lock, flags);

        mod_timer(&nc->monitor.timer, jiffies + HZ);
}

[gwshan]

Joel, thanks for opening a bug to track it down. I already had an fix to address it. As it's trivial fix and this issue won't cause more serious problem, I will post the patch together with others for review afterwards.