linux-kernel - Re: [PATCH v3] Bluetooth: iso: fix socket matching ambiguity between BIS and CIS

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Message-ID: <4e0b2df6-1139-49df-b03b-a2f31925d52f@amlogic.com>
Date: Mon, 4 Aug 2025 09:06:50 +0800
From: Yang Li <yang.li@...ogic.com>
To: Luiz Augusto von Dentz <luiz.dentz@...il.com>
Cc: Marcel Holtmann <marcel@...tmann.org>,
 Johan Hedberg <johan.hedberg@...il.com>, linux-bluetooth@...r.kernel.org,
 linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3] Bluetooth: iso: fix socket matching ambiguity between
 BIS and CIS

Hi Luiz,
> [ EXTERNAL EMAIL ]
>
> Hi Yang,
>
> On Thu, Jul 31, 2025 at 4:00 AM Yang Li via B4 Relay
> <devnull+yang.li.amlogic.com@...nel.org> wrote:
>> From: Yang Li <yang.li@...ogic.com>
>>
>> When both BIS and CIS links exist, their sockets are in
>> the BT_LISTEN state.
> We probably need to introduce tests to iso-test that setup both then
> to avoid reintroducing the problem.


Since the coexistence of BIS sink and CIS sink is determined by 
application-level logic, it may be difficult to reproduce this scenario 
using iso-test.

Do you have any suggestions on how to simulate or test this case more 
effectively?

>
>> dump sock:
>>    sk 000000001977ef51 state 6
>>    src 10:a5:62:31:05:cf dst 00:00:00:00:00:00
>>    sk 0000000031d28700 state 7
>>    src 10:a5:62:31:05:cf dst00:00:00:00:00:00
>>    sk 00000000613af00e state 4   # listen sock of bis
>>    src 10:a5:62:31:05:cf dst 54:00:00:d4:99:30
>>    sk 000000001710468c state 9
>>    src 10:a5:62:31:05:cf dst 54:00:00:d4:99:30
>>    sk 000000005d97dfde state 4   #listen sock of cis
>>    src 10:a5:62:31:05:cf dst 00:00:00:00:00:00
>>
>> To locate the CIS socket correctly, check both the BT_LISTEN
>> state and whether dst addr is BDADDR_ANY.
>>
>> Link: https://github.com/bluez/bluez/issues/1224
>>
>> Signed-off-by: Yang Li <yang.li@...ogic.com>
>> ---
>>   net/bluetooth/iso.c | 9 +++++++--
>>   1 file changed, 7 insertions(+), 2 deletions(-)
>>
>> diff --git a/net/bluetooth/iso.c b/net/bluetooth/iso.c
>> index eaffd25570e3..9a4dea03af8c 100644
>> --- a/net/bluetooth/iso.c
>> +++ b/net/bluetooth/iso.c
>> @@ -1919,6 +1919,11 @@ static bool iso_match_pa_sync_flag(struct sock *sk, void *data)
>>          return test_bit(BT_SK_PA_SYNC, &iso_pi(sk)->flags);
>>   }
>>
>> +static bool iso_match_dst(struct sock *sk, void *data)
>> +{
>> +       return !bacmp(&iso_pi(sk)->dst, (bdaddr_t *)data);
>> +}
>> +
>>   static void iso_conn_ready(struct iso_conn *conn)
>>   {
>>          struct sock *parent = NULL;
>> @@ -1981,7 +1986,7 @@ static void iso_conn_ready(struct iso_conn *conn)
>>
>>                  if (!parent)
>>                          parent = iso_get_sock(&hcon->src, BDADDR_ANY,
>> -                                             BT_LISTEN, NULL, NULL);
>> +                                             BT_LISTEN, iso_match_dst, BDADDR_ANY);
>>
>>                  if (!parent)
>>                          return;
>> @@ -2220,7 +2225,7 @@ int iso_connect_ind(struct hci_dev *hdev, bdaddr_t *bdaddr, __u8 *flags)
>>                  }
>>          } else {
>>                  sk = iso_get_sock(&hdev->bdaddr, BDADDR_ANY,
>> -                                 BT_LISTEN, NULL, NULL);
>> +                                 BT_LISTEN, iso_match_dst, BDADDR_ANY);
> Perhaps we should add helper function that wrap the iso_get_sock (e.g.
> iso_get_sock_cis and iso_get_sock_bis) to make it clearer what is the
> expected socket type, also if the hcon has been set perhaps that
> should be matched as well with CIS_LINK/BIS_LINK, or perhaps we
> introduce a socket type to differentiate since the use of the address
> can make the logic a little confusing when the socket types are mixed
> together.
>
> Now looking at the source code perhaps we can have a separate list for
> cis and bis sockets instead of global iso_sk_list (e.g. cis_sk_list
> and bis_sk_list), that way we don't need a type and there is no risk
> of confusing the sockets since they would never be in the same list.


Alright, I will give it a try.

>
>>          }
>>
>>   done:
>>
>> ---
>> base-commit: 9c533991fe15be60ad9f9a7629c25dbc5b09788d
>> change-id: 20250731-bis_cis_coexist-717a442d5c42
>>
>> Best regards,
>> --
>> Yang Li <yang.li@...ogic.com>
>>
>>
>
> --
> Luiz Augusto von Dentz