netdev - Re: [PATCH v4 net-next 11/19] ionic: Add Rx filter and rx

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Date:   Tue, 23 Jul 2019 22:51:42 +0000
From:   Saeed Mahameed <saeedm@...lanox.com>
To:     "snelson@...sando.io" <snelson@...sando.io>,
        "davem@...emloft.net" <davem@...emloft.net>
CC:     "netdev@...r.kernel.org" <netdev@...r.kernel.org>
Subject: Re: [PATCH v4 net-next 11/19] ionic: Add Rx filter and rx_mode ndo
 support

On Tue, 2019-07-23 at 14:33 -0700, David Miller wrote:
> From: Shannon Nelson <snelson@...sando.io>
> Date: Mon, 22 Jul 2019 14:40:15 -0700
> 
> > +	if (in_interrupt()) {
> > +		work = kzalloc(sizeof(*work), GFP_ATOMIC);
> > +		if (!work) {
> > +			netdev_err(lif->netdev, "%s OOM\n", __func__);
> > +			return -ENOMEM;
> > +		}
> > +		work->type = add ? DW_TYPE_RX_ADDR_ADD :
> > DW_TYPE_RX_ADDR_DEL;
> > +		memcpy(work->addr, addr, ETH_ALEN);
> > +		netdev_dbg(lif->netdev, "deferred: rx_filter %s %pM\n",
> > +			   add ? "add" : "del", addr);
> > +		ionic_lif_deferred_enqueue(&lif->deferred, work);
> > +	} else {
> > +		netdev_dbg(lif->netdev, "rx_filter %s %pM\n",
> > +			   add ? "add" : "del", addr);
> > +		if (add)
> > +			return ionic_lif_addr_add(lif, addr);
> > +		else
> > +			return ionic_lif_addr_del(lif, addr);
> > +	}
> 
> I don't know about this.
> 
> Generally interface address changes are expected to be synchronous.

Well, drivers can't sleep on set_rx_mode ndo, dev_set_rx_mode is
holding netif_addr_lock_bh.

Some drivers need to wait for firmware/device completion to program the
new address and they have to do this asynchronously to avoid atomic
context. I assume this driver is having the same issue due to
"ionic_adminq_post_wait()" ..