netdev - Re: [PATCH net-next v13 01/13] rtase: Add pci table supported in this module

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Message-ID: <20231205194050.7033cc2b@kernel.org>
Date: Tue, 5 Dec 2023 19:40:50 -0800
From: Jakub Kicinski <kuba@...nel.org>
To: Justin Lai <justinlai0215@...ltek.com>
Cc: "davem@...emloft.net" <davem@...emloft.net>, "edumazet@...gle.com"
 <edumazet@...gle.com>, "pabeni@...hat.com" <pabeni@...hat.com>,
 "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
 "netdev@...r.kernel.org" <netdev@...r.kernel.org>, "andrew@...n.ch"
 <andrew@...n.ch>, Ping-Ke Shih <pkshih@...ltek.com>, Larry Chiu
 <larry.chiu@...ltek.com>
Subject: Re: [PATCH net-next v13 01/13] rtase: Add pci table supported in
 this module

On Wed, 6 Dec 2023 03:28:32 +0000 Justin Lai wrote:
> > > +static void rtase_remove_one(struct pci_dev *pdev) {
> > > +     struct net_device *dev = pci_get_drvdata(pdev);
> > > +     struct rtase_private *tp = netdev_priv(dev);
> > > +     struct rtase_int_vector *ivec;
> > > +     u32 i;
> > > +
> > > +     for (i = 0; i < tp->int_nums; i++) {
> > > +             ivec = &tp->int_vector[i];
> > > +             netif_napi_del(&ivec->napi);  
> > 
> > NAPI instances should be added on ndo_open()  
> 
> Do you want me to call netif_napi_add() in the .ndo_open function,
> and netif_napi_del() in the .ndo_stop function? However, I saw that
> many drivers do it in probe and remove. What is the purpose of doing
> this in .ndo_open and .ndo_stop?

They will sit in a fixed-size hash table used for NAPI lookup in the
core. Not a big deal, but not the best way either.

I think the main thing that prompted me to ask was that I couldn't find
napi_disable() in the first few patches. You should probably call it on
close, otherwise making sure NAPI is not running when you start freeing
rings is hard. synchronize_irq() will not help you at all if you're
using NAPI.