linux-kernel - Re: [EXTERNAL] Re: [PATCH net-next] net: mana: Support HW link state events

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Message-ID: <4ea9acfd-be02-4299-b8c4-95bb69ad04cd@lunn.ch>
Date: Tue, 14 Oct 2025 01:21:45 +0200
From: Andrew Lunn <andrew@...n.ch>
To: Haiyang Zhang <haiyangz@...rosoft.com>
Cc: Haiyang Zhang <haiyangz@...ux.microsoft.com>,
	"linux-hyperv@...r.kernel.org" <linux-hyperv@...r.kernel.org>,
	"netdev@...r.kernel.org" <netdev@...r.kernel.org>,
	Paul Rosswurm <paulros@...rosoft.com>,
	Dexuan Cui <decui@...rosoft.com>, KY Srinivasan <kys@...rosoft.com>,
	"wei.liu@...nel.org" <wei.liu@...nel.org>,
	"edumazet@...gle.com" <edumazet@...gle.com>,
	"davem@...emloft.net" <davem@...emloft.net>,
	"kuba@...nel.org" <kuba@...nel.org>,
	"pabeni@...hat.com" <pabeni@...hat.com>,
	Long Li <longli@...rosoft.com>,
	"ssengar@...ux.microsoft.com" <ssengar@...ux.microsoft.com>,
	"ernis@...ux.microsoft.com" <ernis@...ux.microsoft.com>,
	"dipayanroy@...ux.microsoft.com" <dipayanroy@...ux.microsoft.com>,
	Konstantin Taranov <kotaranov@...rosoft.com>,
	"horms@...nel.org" <horms@...nel.org>,
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	"mlevitsk@...hat.com" <mlevitsk@...hat.com>,
	"yury.norov@...il.com" <yury.norov@...il.com>,
	Shiraz Saleem <shirazsaleem@...rosoft.com>,
	"andrew+netdev@...n.ch" <andrew+netdev@...n.ch>,
	"linux-rdma@...r.kernel.org" <linux-rdma@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [EXTERNAL] Re: [PATCH net-next] net: mana: Support HW link state
 events

> > > +		if (link_up) {
> > > +			netif_carrier_on(ndev);
> > > +
> > > +			if (apc->port_is_up)
> > > +				netif_tx_wake_all_queues(ndev);
> > > +
> > > +			__netdev_notify_peers(ndev);
> > > +		} else {
> > > +			if (netif_carrier_ok(ndev)) {
> > > +				netif_tx_disable(ndev);
> > > +				netif_carrier_off(ndev);
> > > +			}
> > > +		}
> > 
> > It is odd this is asymmetric. Up and down should really be opposites.
> For the up event, we need to delay the wake up queues if the 
> mana_close() is called, or mana_open() isn't called yet.
> 
> Also, we notify peers only when link up.

But why is this not symmetric?

On down, if port_is_up is not true, there is no need to disable tx and
set the carrier off. There are also counters associated with
netif_carrier_off() and netif_carrier_on(), and if you don't call them
in symmetric pairs, the counters are going to look odd.

> cancel_work_sync()'s doc says "This function can be used
> even if the work re-queues itself".
> cancel_delayed_work_sync() calls the same underlying function but 
> with WORK_CANCEL_DELAYED flag. So it should be OK.

O.K, thanks

	Andrew