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

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Date:   Thu, 7 Oct 2021 17:47:41 +0200
From:   Marcel Holtmann <marcel@...tmann.org>
To:     Luiz Augusto von Dentz <luiz.dentz@...il.com>
Cc:     Colin King <colin.king@...onical.com>,
        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 Luiz,

>> 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.

so should I take the patch "Fix wake up suspend_wait_q prematurely” completely out?

Regards

Marcel