linux-kernel - Re: [PATCH][next] Bluetooth: use bitmap_empty to check if a bitmap has any bits set

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Message-ID: <CABBYNZKzVtyZ_qO8pvenSLFRdm9aumxD_-Src4VG3UHQa8y+1w@mail.gmail.com>
Date:   Thu, 7 Oct 2021 08:34:54 -0700
From:   Luiz Augusto von Dentz <luiz.dentz@...il.com>
To:     Colin King <colin.king@...onical.com>
Cc:     Marcel Holtmann <marcel@...tmann.org>,
        Johan Hedberg <johan.hedberg@...il.com>,
        "David S . Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        "linux-bluetooth@...r.kernel.org" <linux-bluetooth@...r.kernel.org>,
        "open list:NETWORKING [GENERAL]" <netdev@...r.kernel.org>,
        kernel-janitors@...r.kernel.org,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH][next] Bluetooth: use bitmap_empty to check if a bitmap
 has any bits set

Hi Colin,

On Thu, Oct 7, 2021 at 4:17 AM Colin King <colin.king@...onical.com> wrote:
>
> From: Colin Ian King <colin.king@...onical.com>
>
> The check to see if any tasks are left checks if bitmap array is zero
> rather than using the appropriate bitmap helper functions to check the
> bits in the array. Fix this by using bitmap_empty on the bitmap.
>
> Addresses-Coverity: (" Array compared against 0")
> Fixes: 912730b52552 ("Bluetooth: Fix wake up suspend_wait_q prematurely")
> Signed-off-by: Colin Ian King <colin.king@...onical.com>
> ---
>  net/bluetooth/hci_request.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/net/bluetooth/hci_request.c b/net/bluetooth/hci_request.c
> index 209f4fe17237..bad3b9c895ba 100644
> --- a/net/bluetooth/hci_request.c
> +++ b/net/bluetooth/hci_request.c
> @@ -1108,7 +1108,7 @@ static void suspend_req_complete(struct hci_dev *hdev, u8 status, u16 opcode)
>         clear_bit(SUSPEND_SET_ADV_FILTER, hdev->suspend_tasks);
>
>         /* Wake up only if there are no tasks left */
> -       if (!hdev->suspend_tasks)
> +       if (!bitmap_empty(hdev->suspend_tasks, __SUSPEND_NUM_TASKS))
>                 wake_up(&hdev->suspend_wait_q);
>  }
>
> --
> 2.32.0

I was going to revert this change since it appears wake_up does
actually check the wake condition there is no premature wake up after
all.

-- 
Luiz Augusto von Dentz