linux-kernel - Re: [PATCH] Bluetooth: Clear suspend tasks on unregister

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Date:   Mon, 31 Aug 2020 17:49:54 +0200
From:   Marcel Holtmann <marcel@...tmann.org>
To:     Abhishek Pandit-Subedi <abhishekpandit@...omium.org>
Cc:     linux-bluetooth <linux-bluetooth@...r.kernel.org>,
        CrosBT Upstreaming <chromeos-bluetooth-upstreaming@...omium.org>,
        "David S. Miller" <davem@...emloft.net>,
        Johan Hedberg <johan.hedberg@...il.com>,
        netdev <netdev@...r.kernel.org>,
        kernel list <linux-kernel@...r.kernel.org>,
        Jakub Kicinski <kuba@...nel.org>,
        Miao-chen Chou <mcchou@...omium.org>
Subject: Re: [PATCH] Bluetooth: Clear suspend tasks on unregister

Hi Abhishek,

> While unregistering, make sure to clear the suspend tasks before
> cancelling the work. If the unregister is called during resume from
> suspend, this will unnecessarily add 2s to the resume time otherwise.
> 
> Fixes: 4e8c36c3b0d73d (Bluetooth: Fix suspend notifier race)
> Signed-off-by: Abhishek Pandit-Subedi <abhishekpandit@...omium.org>
> ---
> This was discovered with RT8822CE using the btusb driver. This chipset
> will reset on resume during system suspend and was unnecessarily adding
> 2s to every resume. Since we're unregistering anyway, there's no harm in
> just clearing the pending events.
> 
> net/bluetooth/hci_core.c | 11 +++++++++++
> 1 file changed, 11 insertions(+)
> 
> diff --git a/net/bluetooth/hci_core.c b/net/bluetooth/hci_core.c
> index 68bfe57b66250f..ed4cb3479433c0 100644
> --- a/net/bluetooth/hci_core.c
> +++ b/net/bluetooth/hci_core.c
> @@ -3442,6 +3442,16 @@ void hci_copy_identity_address(struct hci_dev *hdev, bdaddr_t *bdaddr,
> 	}
> }
> 
> +static void hci_suspend_clear_tasks(struct hci_dev *hdev)
> +{
> +	int i;
> +
> +	for (i = 0; i < __SUSPEND_NUM_TASKS; ++i)
> +		clear_bit(i, hdev->suspend_tasks);

I prefer i++ instead of ++i.

Regards

Marcel