linux-kernel - Re: [PATCH v2 1/4] Bluetooth: Keep MSFT ext info throughout a hci

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Message-Id: <7B6FEB99-5102-4A67-986C-4A5DEFDE2166@holtmann.org>
Date:   Fri, 18 Dec 2020 22:39:22 +0100
From:   Marcel Holtmann <marcel@...tmann.org>
To:     Miao-chen Chou <mcchou@...omium.org>
Cc:     Bluetooth Kernel Mailing List <linux-bluetooth@...r.kernel.org>,
        Alain Michaud <alainm@...omium.org>,
        Luiz Augusto von Dentz <luiz.von.dentz@...el.com>,
        Archie Pusaka <apusaka@...omium.org>,
        Abhishek Pandit-Subedi <abhishekpandit@...omium.org>,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        Johan Hedberg <johan.hedberg@...il.com>,
        Luiz Augusto von Dentz <luiz.dentz@...il.com>,
        linux-kernel@...r.kernel.org, netdev@...r.kernel.org
Subject: Re: [PATCH v2 1/4] Bluetooth: Keep MSFT ext info throughout a
 hci_dev's life cycle

Hi Miao-chen,

> This moves msft_do_close() from hci_dev_do_close() to
> hci_unregister_dev() to avoid clearing MSFT extension info. This also
> avoids retrieving MSFT info upon every msft_do_open() if MSFT extension
> has been initialized.

what is the actual benefit of this?

It is fundamentally one extra HCI command and that one does no harm. You are trying to outsmart the hdev->setup vs the !hdev->setup case. I don’t think this is a good idea.

So unless I see a real argument why we want to do this, I am leaving this patch out. And on a side note, I named these function exactly this way so they are symmetric with hci_dev_do_{open,close}.

Regards

Marcel