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* [PATCH BlueZ v2] avdtp: wait for L2CAP Disconnect Rsp before CLOSING->IDLE
@ 2025-09-14 12:56 Pauli Virtanen
  2025-09-14 14:21 ` [BlueZ,v2] " bluez.test.bot
  2025-09-15 13:40 ` [PATCH BlueZ v2] " patchwork-bot+bluetooth
  0 siblings, 2 replies; 3+ messages in thread
From: Pauli Virtanen @ 2025-09-14 12:56 UTC (permalink / raw)
  To: linux-bluetooth; +Cc: Pauli Virtanen

Delay CLOSING->IDLE until remote acknowledges L2CAP channel closure.

It is not explicitly stated in AVDTP v1.3 Sec. 6.13, but some devices
refuse commands sent immediately after L2CAP Disconnect Req, so wait
until Rsp.

Fails:

> ACL Data RX: Handle 6 flags 0x02 dlen 6
      Channel: 64 len 2 [PSM 25 mode Basic (0x00)] {chan 0}
      AVDTP: Close (0x08) Response Accept (0x02) type 0x00 label 0 nosp 0
< ACL Data TX: Handle 6 flags 0x00 dlen 12
      L2CAP: Disconnection Request (0x06) ident 16 len 4
        Destination CID: 65
        Source CID: 65
< ACL Data TX: Handle 6 flags 0x00 dlen 22
      Channel: 64 len 18 [PSM 25 mode Basic (0x00)] {chan 0}
      AVDTP: Set Configuration (0x03) Command (0x00) type 0x00 label 1 nosp 0
        ACP SEID: 7
        INT SEID: 1
        Service Category: Media Transport (0x01)
        Service Category: Media Codec (0x07)
          Media Type: Audio (0x00)
          Media Codec: MPEG-2,4 AAC (0x02)
            Object Type: MPEG-4 AAC LC (0x40)
            Frequency: 44100 (0x100)
            Channels: 2 (0x04)
            Bitrate: 220000bps
            VBR: No
        Service Category: Delay Reporting (0x08)
> ACL Data RX: Handle 6 flags 0x02 dlen 12
      L2CAP: Disconnection Response (0x07) ident 16 len 4
        Destination CID: 65
        Source CID: 65
> ACL Data RX: Handle 6 flags 0x02 dlen 8
      Channel: 64 len 4 [PSM 25 mode Basic (0x00)] {chan 0}
      AVDTP: Set Configuration (0x03) Response Reject (0x03) type 0x00 label 1 nosp 0
        Service Category: Reserved (0x29)
        Error code: UNSUPPORTED_CONFIGURATION (0x29)

Works:

> ACL Data RX: Handle 4 flags 0x02 dlen 6
      Channel: 64 len 2 [PSM 25 mode Basic (0x00)] {chan 0}
      AVDTP: Close (0x08) Response Accept (0x02) type 0x00 label 12 nosp 0
< ACL Data TX: Handle 4 flags 0x00 dlen 12
      L2CAP: Disconnection Request (0x06) ident 16 len 4
        Destination CID: 65
        Source CID: 65
> ACL Data RX: Handle 4 flags 0x02 dlen 12
      L2CAP: Disconnection Response (0x07) ident 16 len 4
        Destination CID: 65
        Source CID: 65
< ACL Data TX: Handle 4 flags 0x00 dlen 22
      Channel: 64 len 18 [PSM 25 mode Basic (0x00)] {chan 0}
      AVDTP: Set Configuration (0x03) Command (0x00) type 0x00 label 13 nosp 0
        ACP SEID: 9
        INT SEID: 2
        Service Category: Media Transport (0x01)
        Service Category: Media Codec (0x07)
          Media Type: Audio (0x00)
          Media Codec: MPEG-2,4 AAC (0x02)
            Object Type: MPEG-4 AAC LC (0x40)
            Frequency: 44100 (0x100)
            Channels: 2 (0x04)
            Bitrate: 220000bps
            VBR: No
        Service Category: Delay Reporting (0x08)
> ACL Data RX: Handle 4 flags 0x02 dlen 6
      Channel: 64 len 2 [PSM 25 mode Basic (0x00)] {chan 0}
      AVDTP: Set Configuration (0x03) Response Accept (0x02) type 0x00 label 13 nosp 0

Fixes: https://github.com/bluez/bluez/issues/1471
Fixes: aa118e965b ("a2dp: Don't wait to reconfigure")
---

Notes:
    v2:
    - SHUT_WR is a much simpler way to do it. This leaves dealing with any
      L2CAP timeouts to the kernel.

 profiles/audio/avdtp.c | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/profiles/audio/avdtp.c b/profiles/audio/avdtp.c
index 30648251f..2f6eaf2ea 100644
--- a/profiles/audio/avdtp.c
+++ b/profiles/audio/avdtp.c
@@ -752,6 +752,8 @@ static void transport_cb(int cond, void *data)
 	struct avdtp_stream *stream = data;
 	struct avdtp_local_sep *sep = stream->lsep;
 
+	DBG("");
+
 	if (stream->close_int && sep->cfm && sep->cfm->close)
 		sep->cfm->close(stream->session, sep, stream, NULL,
 				sep->user_data);
@@ -2922,7 +2924,14 @@ static gboolean avdtp_close_resp(struct avdtp *session,
 {
 	avdtp_stream_set_state(stream, AVDTP_STATE_CLOSING);
 
-	close_stream(stream);
+	/* Delay CLOSING->IDLE until remote acknowledges L2CAP channel closure.
+	 *
+	 * It is not explicitly stated in AVDTP v1.3 Sec. 6.13, but some devices
+	 * refuse commands sent immediately after L2CAP Disconnect Req, so wait
+	 * until Rsp.
+	 */
+	if (stream->io)
+		shutdown(g_io_channel_unix_get_fd(stream->io), SHUT_WR);
 
 	return TRUE;
 }
-- 
2.51.0


^ permalink raw reply related	[flat|nested] 3+ messages in thread
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2025-09-14 12:56 [PATCH BlueZ v2] avdtp: wait for L2CAP Disconnect Rsp before CLOSING->IDLE Pauli Virtanen
2025-09-14 14:21 ` [BlueZ,v2] " bluez.test.bot
2025-09-15 13:40 ` [PATCH BlueZ v2] " patchwork-bot+bluetooth

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