[PATCH] Bluetooth: hci_h5: Complements reliable packet processing logic.

[PATCH] Bluetooth: hci_h5: Complements reliable packet processing logic.

[Qiqi Zhang]

As shown in the schematic diagram below.There may be a critical
scenario in the current code. If the device does not receive an
pure ack sent by the host due to insufficient receive buffer or
other reasons and triggers a retransmission, the host will always
be in an 'out-of-order' state.The state machine will get stuck.

       host                 device
     SEQ3,ACK4 --------->
               <--------- SEQ4,ACK4
     pure ACK  ---------> (not received)
(out-of-order) <--------- SEQ4,ACK4(retransmission)
		........
(out-of-order) <--------- SEQ4,ACK4(retransmission)

According to the description in the core specification: "whenever
a reliable packet is received, an acknowledgment shall be generated."
we should set H5_TX_ACK_REQ bit to trigger retransmission of pure ack
packet when "out-of-order" occurs.

Signed-off-by: Qiqi Zhang <eddy.zhang@rock-chips.com>
---
 drivers/bluetooth/hci_h5.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/bluetooth/hci_h5.c b/drivers/bluetooth/hci_h5.c
index 6455bc4fb5bb..d05eaeaa4516 100644
--- a/drivers/bluetooth/hci_h5.c
+++ b/drivers/bluetooth/hci_h5.c
@@ -463,6 +463,8 @@ static int h5_rx_3wire_hdr(struct hci_uart *hu, unsigned char c)
 	if (H5_HDR_RELIABLE(hdr) && H5_HDR_SEQ(hdr) != h5->tx_ack) {
 		bt_dev_err(hu->hdev, "Out-of-order packet arrived (%u != %u)",
 			   H5_HDR_SEQ(hdr), h5->tx_ack);
+		set_bit(H5_TX_ACK_REQ, &h5->flags);
+		hci_uart_tx_wakeup(hu);
 		h5_reset_rx(h5);
 		return 0;
 	}
-- 
2.25.1

[PATCH v2] Bluetooth: hci_h5: Complements reliable packet processing logic

[Qiqi Zhang]

As shown in the schematic diagram below.There may be a critical
scenario in the current code. If the device does not receive an
pure ack sent by the host due to insufficient receive buffer or
other reasons and triggers a retransmission, the host will always
be in an 'out-of-order' state.The state machine will get stuck.

       host                 device
     SEQ3,ACK4 --------->
               <--------- SEQ4,ACK4
     pure ACK  ---------> (not received)
(out-of-order) <--------- SEQ4,ACK4(retransmission)
                ........
(out-of-order) <--------- SEQ4,ACK4(retransmission)

According to the description in the core specification: "whenever
a reliable packet is received, an acknowledgment shall be generated."
So set H5_TX_ACK_REQ bit to trigger retransmission of pure ack packet
when "out-of-order" occurs.

Signed-off-by: Qiqi Zhang <eddy.zhang@rock-chips.com>
---
Changes in v2:
- Fixed build bot warning.
---
---
 drivers/bluetooth/hci_h5.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/bluetooth/hci_h5.c b/drivers/bluetooth/hci_h5.c
index 6455bc4fb5bb..d05eaeaa4516 100644
--- a/drivers/bluetooth/hci_h5.c
+++ b/drivers/bluetooth/hci_h5.c
@@ -463,6 +463,8 @@ static int h5_rx_3wire_hdr(struct hci_uart *hu, unsigned char c)
 	if (H5_HDR_RELIABLE(hdr) && H5_HDR_SEQ(hdr) != h5->tx_ack) {
 		bt_dev_err(hu->hdev, "Out-of-order packet arrived (%u != %u)",
 			   H5_HDR_SEQ(hdr), h5->tx_ack);
+		set_bit(H5_TX_ACK_REQ, &h5->flags);
+		hci_uart_tx_wakeup(hu);
 		h5_reset_rx(h5);
 		return 0;
 	}
-- 
2.25.1

Re: [PATCH] Bluetooth: hci_h5: Complements reliable packet processing logic.

[patchwork-bot+bluetooth]

Hello:

This patch was applied to bluetooth/bluetooth-next.git (master)
by Luiz Augusto von Dentz <luiz.von.dentz@intel.com>:

On Tue,  4 Apr 2023 00:29:28 +0800 you wrote:
> As shown in the schematic diagram below.There may be a critical
> scenario in the current code. If the device does not receive an
> pure ack sent by the host due to insufficient receive buffer or
> other reasons and triggers a retransmission, the host will always
> be in an 'out-of-order' state.The state machine will get stuck.
> 
>        host                 device
>      SEQ3,ACK4 --------->
>                <--------- SEQ4,ACK4
>      pure ACK  ---------> (not received)
> (out-of-order) <--------- SEQ4,ACK4(retransmission)
> 		........
> (out-of-order) <--------- SEQ4,ACK4(retransmission)
> 
> [...]

Here is the summary with links:
  - Bluetooth: hci_h5: Complements reliable packet processing logic.
    https://git.kernel.org/bluetooth/bluetooth-next/c/13a6ebae665d

You are awesome, thank you!
-- 
Deet-doot-dot, I am a bot.
https://korg.docs.kernel.org/patchwork/pwbot.html

Re: [PATCH v2] Bluetooth: hci_h5: Complements reliable packet processing logic

[patchwork-bot+bluetooth]

Hello:

This patch was applied to bluetooth/bluetooth-next.git (master)
by Luiz Augusto von Dentz <luiz.von.dentz@intel.com>:

On Tue,  4 Apr 2023 10:27:11 +0800 you wrote:
> As shown in the schematic diagram below.There may be a critical
> scenario in the current code. If the device does not receive an
> pure ack sent by the host due to insufficient receive buffer or
> other reasons and triggers a retransmission, the host will always
> be in an 'out-of-order' state.The state machine will get stuck.
> 
>        host                 device
>      SEQ3,ACK4 --------->
>                <--------- SEQ4,ACK4
>      pure ACK  ---------> (not received)
> (out-of-order) <--------- SEQ4,ACK4(retransmission)
>                 ........
> (out-of-order) <--------- SEQ4,ACK4(retransmission)
> 
> [...]

Here is the summary with links:
  - [v2] Bluetooth: hci_h5: Complements reliable packet processing logic
    https://git.kernel.org/bluetooth/bluetooth-next/c/13a6ebae665d

You are awesome, thank you!
-- 
Deet-doot-dot, I am a bot.
https://korg.docs.kernel.org/patchwork/pwbot.html