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Date: Fri, 31 Jul 2020 20:45:02 +0300 From: Sergei Shtylyov <sergei.shtylyov@...il.com> To: Yoshihiro Shimoda <yoshihiro.shimoda.uh@...esas.com>, Yuusuke Ashizuka <ashiduka@...itsu.com> Cc: "netdev@...r.kernel.org" <netdev@...r.kernel.org>, "linux-renesas-soc@...r.kernel.org" <linux-renesas-soc@...r.kernel.org> Subject: Re: [PATCH v2] ravb: Fixed the problem that rmmod can not be done Hello! On 7/31/20 9:43 AM, Yoshihiro Shimoda wrote: >>>> From: Yuusuke Ashizuka, Sent: Thursday, July 30, 2020 7:02 PM >>>> Subject: [PATCH v2] ravb: Fixed the problem that rmmod can not be done >>> >>> Thank you for the patch! I found a similar patch for another driver [1]. >> >> It's not the same case -- that driver hadn't had the MDIO release code at all >> before that patch. > > You're correct. I didn't realized it... The patch description was somewhat incomplete there... >>> So, we should apply this patch to the ravb driver. >> >> I believe the driver is innocent. :-) > > I hope so :) Looks like I was wrong in this case. It's very fortunate that the MDIO bitbang is not as popular as I thought. > <snip> >>>> $ lsmod >>>> Module Size Used by >>>> ravb 40960 1 >>>> $ rmmod ravb >>>> rmmod: ERROR: Module ravb is in use >> >> Shouldn't the driver core call the remove() method for the affected devices >> first, before checking the refcount? > > In this case, an mii bus of "mdiobb_ops bb_ops" is affected "device" by the ravb driver. > And the ravb driver sets the owner of mii bus as THIS_MODULE like below: > > static struct mdiobb_ops bb_ops = { > .owner = THIS_MODULE, > .set_mdc = ravb_set_mdc, > .set_mdio_dir = ravb_set_mdio_dir, > .set_mdio_data = ravb_set_mdio_data, > .get_mdio_data = ravb_get_mdio_data, > }; > > So, I don't think the driver core can call the remove() method for the mii bus > because it's a part of the ravb driver... And because the MDIO module just doesn't have the usual method! :-) (I meant the EtherAVB driver's remove() method, and that one would be called after a successful reference count check...) > By the way, about the mdio-gpio driver, I'm wondering if the mdio-gpio > driver cannot be removed by rmmod too. (perhaps, we need "rmmod -f" to remove it.) You're on your own here. It's fortunate for this patch that I'm not currently loaded at work! :-) >>> By the way, I think you have to send this patch to the following maintainers too: >>> # We can get it by using scripts/get_maintainers.pl. >>> David S. Miller <davem@...emloft.net> (maintainer:NETWORKING DRIVERS,commit_signer:8/8=100%) >>> Jakub Kicinski <kuba@...nel.org> (maintainer:NETWORKING DRIVERS) Not critical, as DaveM uses the patchwork anyway. He started to be CC'ed on netdev patches only recently. :-) [...] > Best regards, > Yoshihiro Shimoda MBR, Sergei
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