Hi Andrei,
On Wed, Apr 18, 2012 at 4:16 AM, Andrei Emeltchenko
<andrei.emeltchenko.news@xxxxxxxxx> wrote:
> Hi Ulisses,
>
> On Tue, Apr 17, 2012 at 10:41:27AM -0300, Ulisses Furquim wrote:
>> When adding HCI devices hci_register_dev assigns the same name
>> hci1 for subsequently added AMP devices.
>>
>> ...
>> [ 6958.381886] sysfs: cannot create duplicate filename
>> '/devices/virtual/bluetooth/hci1
>> ...
>>
>> We assume id starts with the number we'll try to add the new device
>> and keep iterating until we find the proper place. The only difference
>> is we start with 0 for BR/EDR device and 1 for AMP devices (thus AMP
>> devices will never receive register as index 0). Then every hdev->id in
>> the _ordered_ list <= to the id we want we increment id and move the
>> variable head. In the end we'll have id as the first available one and
>> head is where you need to add hdev after to keep the list ordered.
>>
>> Reported-by: Andrei Emeltchenko <andrei.emeltchenko@xxxxxxxxx>
>> Signed-off-by: Ulisses Furquim <ulisses@xxxxxxxxxxxxxx>
>> ---
>>
>> v2 - only increment id when we find it's already there in the list.
>>
>> ---
>> net/bluetooth/hci_core.c | 7 +++++--
>> 1 file changed, 5 insertions(+), 2 deletions(-)
>>
>> diff --git a/net/bluetooth/hci_core.c b/net/bluetooth/hci_core.c
>> index c4dc263..e2202a1 100644
>> --- a/net/bluetooth/hci_core.c
>> +++ b/net/bluetooth/hci_core.c
>> @@ -1754,9 +1754,12 @@ int hci_register_dev(struct hci_dev *hdev)
>>
>> /* Find first available device id */
>> list_for_each(p, &hci_dev_list) {
>> - if (list_entry(p, struct hci_dev, list)->id != id)
>> + int nid = list_entry(p, struct hci_dev, list)->id;
>
> this looks bad IMO, better use hdev = list_entry
Why? I only need to use the id field, after all.
>> + if (nid > id)
>> break;
>> - head = p; id++;
>> + if (nid == id)
>> + id++;
>> + head = p;
>> }
>
> This does not work when creating 3rd AMP device:
>
> [ 121.925367] Bluetooth: Chosen id 1
> [ 121.958056] Created virtual AMP device hci1
>
> [ 131.588553] Bluetooth: list: hdev->id 1 id 1
> [ 131.661149] Bluetooth: Chosen id 2
>
> [ 131.681159] Created virtual AMP device hci2
> [ 139.904674] Bluetooth: list: hdev->id 2 id 1
> [ 139.943904] Bluetooth: Chosen id 1
> [ 139.944780] ------------[ cut here ]------------
> [ 139.957882] WARNING: at fs/sysfs/dir.c:508 sysfs_add_one+0x9b/0xd0()
> ...
>
> I suspect that you have to handle 2 cases when you add new device after or
> before head otherwise list gets un-ordered.
Thanks a lot for testing, Andrei. This bug is because I must be
sleeping really bad. :-/ I even say in the commit message we should
add hdev _after_ head and keep using list_add_tail()?! Fixed version
of the patch coming in a few minutes.
Regards,
--
Ulisses Furquim
ProFUSION embedded systems
http://profusion.mobi
Mobile: +55 19 9250 0942
Skype: ulissesffs
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