netdev - Re: [PATCH v0] idb: Add rtnl

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Date:   Tue, 9 Aug 2022 11:05:19 +0800 (GMT+08:00)
From:   "Lin Ma" <linma@....edu.cn>
To:     "Jakub Kicinski" <kuba@...nel.org>
Cc:     jesse.brandeburg@...el.com, anthony.l.nguyen@...el.com,
        davem@...emloft.net, edumazet@...gle.com, pabeni@...hat.com,
        ast@...nel.org, daniel@...earbox.net, hawk@...nel.org,
        john.fastabend@...il.com, intel-wired-lan@...ts.osuosl.org,
        netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
        bpf@...r.kernel.org
Subject: Re: [PATCH v0] idb: Add rtnl_lock to avoid data race

Hello there,

> 
> What about the disable path coming from sysfs? This looks incomplete to
> me. Perhaps take a look at commit 1e53834ce541 ("ixgbe: Add locking to
> prevent panic when setting sriov_numvfs to zero") for some inspiration.

Thanks for the advice, I sent the new version of the patch which uses a new spinlock to avoid race cases such as described in commit 1e53834ce541.

Additionally, I also keep the rtnl_lock to eliminate the races that come from netdev core. Although this can also be handled with the newly added spinlock, I found that adding the spinlock every time accessing the VF resources is not trivial.
(If you think that keep using the spinlock is better I will craft a new version of patch)

It seems that ixgbe_disable_sriov also suffers from the mentioned races from netdev core. If you think the rtnl_lock solution is fine, I will also send a patch for that driver too.

Thanks
Lin Ma