Re: [PATCH net-next 7/7] net: marvell: prestera: fix port event handling on init

From: Vadym Kochan <vadym.kochan@plvision.eu>
To: Jakub Kicinski <kuba@kernel.org>
Cc: "David S. Miller" <davem@davemloft.net>,
	Oleksandr Mazur <oleksandr.mazur@plvision.eu>,
	Serhiy Boiko <serhiy.boiko@plvision.eu>,
	Serhiy Pshyk <serhiy.pshyk@plvision.eu>,
	Volodymyr Mytnyk <volodymyr.mytnyk@plvision.eu>,
	Taras Chornyi <taras.chornyi@plvision.eu>,
	netdev@vger.kernel.org, Mickey Rachamim <mickeyr@marvell.com>,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH net-next 7/7] net: marvell: prestera: fix port event handling on init
Date: Fri, 5 Feb 2021 14:31:07 +0200	[thread overview]
Message-ID: <20210205123107.GD19627@plvision.eu> (raw)
In-Reply-To: <20210204211934.273e54bf@kicinski-fedora-pc1c0hjn.dhcp.thefacebook.com>

Hi Jakub,

On Thu, Feb 04, 2021 at 09:19:34PM -0800, Jakub Kicinski wrote:
> On Wed,  3 Feb 2021 18:54:58 +0200 Vadym Kochan wrote:
> > For some reason there might be a crash during ports creation if port
> > events are handling at the same time  because fw may send initial
> > port event with down state.
> > 
> > The crash points to cancel_delayed_work() which is called when port went
> > is down.  Currently I did not find out the real cause of the issue, so
> > fixed it by cancel port stats work only if previous port's state was up
> > & runnig.
> 
> Maybe you just need to move the DELAYED_WORK_INIT() earlier?
> Not sure why it's at the end of prestera_port_create(), it 
> just initializes some fields.
> 

Thanks for suggestion, but it does not help. Will try to find-out the
real root cause but this is the only fix I 'v came up.

> > [   28.489791] Call trace:
> > [   28.492259]  get_work_pool+0x48/0x60
> > [   28.495874]  cancel_delayed_work+0x38/0xb0
> > [   28.500011]  prestera_port_handle_event+0x90/0xa0 [prestera]
> > [   28.505743]  prestera_evt_recv+0x98/0xe0 [prestera]
> > [   28.510683]  prestera_fw_evt_work_fn+0x180/0x228 [prestera_pci]
> > [   28.516660]  process_one_work+0x1e8/0x360
> > [   28.520710]  worker_thread+0x44/0x480
> > [   28.524412]  kthread+0x154/0x160
> > [   28.527670]  ret_from_fork+0x10/0x38
> > [   28.531290] Code: a8c17bfd d50323bf d65f03c0 9278dc21 (f9400020)
> > [   28.537429] ---[ end trace 5eced933df3a080b ]---
> > 
> > Signed-off-by: Vadym Kochan <vadym.kochan@plvision.eu>
> > ---
> >  drivers/net/ethernet/marvell/prestera/prestera_main.c | 3 ++-
> >  1 file changed, 2 insertions(+), 1 deletion(-)
> > 
> > diff --git a/drivers/net/ethernet/marvell/prestera/prestera_main.c b/drivers/net/ethernet/marvell/prestera/prestera_main.c
> > index 39465e65d09b..122324dae47d 100644
> > --- a/drivers/net/ethernet/marvell/prestera/prestera_main.c
> > +++ b/drivers/net/ethernet/marvell/prestera/prestera_main.c
> > @@ -433,7 +433,8 @@ static void prestera_port_handle_event(struct prestera_switch *sw,
> >  			netif_carrier_on(port->dev);
> >  			if (!delayed_work_pending(caching_dw))
> >  				queue_delayed_work(prestera_wq, caching_dw, 0);
> > -		} else {
> > +		} else if (netif_running(port->dev) &&
> > +			   netif_carrier_ok(port->dev)) {
> >  			netif_carrier_off(port->dev);
> >  			if (delayed_work_pending(caching_dw))
> >  				cancel_delayed_work(caching_dw);
> 