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Date:   Sat, 26 Mar 2022 00:12:28 +0000
From:   William McVicker <willmcvicker@google.com>
To:     Jakub Kicinski <kuba@kernel.org>
Cc:     Johannes Berg <johannes@sipsolutions.net>,
        linux-wireless@vger.kernel.org,
        Marek Szyprowski <m.szyprowski@samsung.com>,
        Kalle Valo <kvalo@codeaurora.org>,
        "David S. Miller" <davem@davemloft.net>, netdev@vger.kernel.org,
        Amitkumar Karwar <amitkarwar@gmail.com>,
        Ganapathi Bhat <ganapathi.bhat@nxp.com>,
        Xinming Hu <huxinming820@gmail.com>, kernel-team@android.com,
        Paolo Abeni <pabeni@redhat.com>
Subject: Re: [BUG] deadlock in nl80211_vendor_cmd
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On 03/25/2022, Jakub Kicinski wrote:
> On Fri, 25 Mar 2022 23:57:33 +0000 William McVicker wrote:
> > Instead of open coding it, we could just pass the internal_flags via struct
> > genl_info to nl80211_vendor_cmds() and then handle the rtnl_unlock() there if
> > the vendor command doesn't request it. I included the patch below in case
> > there's any chance you would consider this for upstream. This would at least
> > add backwards compatibility to the vendor ops API so that existing drivers that
> > depend on the RTNL being held don't need to be fully refactored.
> 
> Sorry to step in, Johannes may be AFK already. There's no asterisk next
> to the "we don't cater to out of tree code" rule, AFAIK.  We change
> locking often, making a precedent like this would be ill-advised.

Yeah I understand. I'll talk to Broadcom about this to see why they didn't use
the existing upstream NAN interface. This sounds like it's going to be
a problem for all the Android out-of-tree drivers.

Thanks for the help!

--Will