netdev - RE: [PATCH net v3 1/1] net: phylink: Add module

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Date: Thu, 11 Jan 2024 06:38:58 +0000
From: "Gan, Yi Fang" <yi.fang.gan@...el.com>
To: Andrew Lunn <andrew@...n.ch>
CC: Russell King <linux@...linux.org.uk>, Heiner Kallweit
	<hkallweit1@...il.com>, "David S . Miller" <davem@...emloft.net>, "Eric
 Dumazet" <edumazet@...gle.com>, Jakub Kicinski <kuba@...nel.org>, Paolo Abeni
	<pabeni@...hat.com>, Marek Behún <kabel@...nel.org>,
	"netdev@...r.kernel.org" <netdev@...r.kernel.org>,
	"linux-stm32@...md-mailman.stormreply.com"
	<linux-stm32@...md-mailman.stormreply.com>,
	"linux-arm-kernel@...ts.infradead.org"
	<linux-arm-kernel@...ts.infradead.org>, "linux-kernel@...r.kernel.org"
	<linux-kernel@...r.kernel.org>, "Looi, Hong Aun" <hong.aun.looi@...el.com>,
	"Voon, Weifeng" <weifeng.voon@...el.com>, "Song, Yoong Siang"
	<yoong.siang.song@...el.com>, "Choong, Yong Liang"
	<yong.liang.choong@...el.com>
Subject: RE: [PATCH net v3 1/1] net: phylink: Add module_exit()



> -----Original Message-----
> From: Andrew Lunn <andrew@...n.ch>
> Sent: Thursday, January 4, 2024 9:05 PM
> To: Gan, Yi Fang <yi.fang.gan@...el.com>
> Cc: Russell King <linux@...linux.org.uk>; Heiner Kallweit
> <hkallweit1@...il.com>; David S . Miller <davem@...emloft.net>; Eric
> Dumazet <edumazet@...gle.com>; Jakub Kicinski <kuba@...nel.org>; Paolo
> Abeni <pabeni@...hat.com>; Marek Behún <kabel@...nel.org>;
> netdev@...r.kernel.org; linux-stm32@...md-mailman.stormreply.com; linux-
> arm-kernel@...ts.infradead.org; linux-kernel@...r.kernel.org; Looi, Hong Aun
> <hong.aun.looi@...el.com>; Voon, Weifeng <weifeng.voon@...el.com>; Song,
> Yoong Siang <yoong.siang.song@...el.com>; Choong, Yong Liang
> <yong.liang.choong@...el.com>
> Subject: Re: [PATCH net v3 1/1] net: phylink: Add module_exit()
> 
> On Thu, Jan 04, 2024 at 06:12:55PM +0800, Gan, Yi Fang wrote:
> 65;7401;1c> In delete_module(), if mod->init callback is defined but mod->exit
> callback
> > is not defined, it will assume the module cannot be removed and return
> > EBUSY. The module_exit() is missing from current phylink module drive
> > causing failure while unloading it.
> 
> This is still missing the explanation why this is safe.
> 
> 
>     Andrew
> 
> ---
> pw-bot: cr

Hi Andrew,

Regarding the justification on why it is safe to remove phylink, 
we had done some memory leak check when unloading the phylink module.
 
root@...alhost:~# lsmod | grep "phylink"
phylink               73728  0
root@...alhost:~# rmmod phylink
root@...alhost:~# echo scan > /sys/kernel/debug/kmemleak
root@...alhost:~# cat /sys/kernel/debug/kmemleak
root@...alhost:~#
 
So far, we didn't observe any memory leaking happened when unloading
phylink module. Is it sufficient or do you have any other suggestions to check 
on whether the module is safe to remove?

Best Regards,
Gan Yi Fang