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Date: Fri, 23 Apr 2021 09:06:10 +0200
From: Marcel Holtmann <marcel@...tmann.org>
To: Manish Mandlik <mmandlik@...gle.com>
Cc: Luiz Augusto von Dentz <luiz.dentz@...il.com>,
Alain Michaud <alainm@...omium.org>,
Bluetooth Kernel Mailing List
<linux-bluetooth@...r.kernel.org>,
CrosBT Upstreaming <chromeos-bluetooth-upstreaming@...omium.org>,
Abhishek Pandit-Subedi <abhishekpandit@...omium.org>,
"David S. Miller" <davem@...emloft.net>,
Jakub Kicinski <kuba@...nel.org>,
Johan Hedberg <johan.hedberg@...il.com>,
open list <linux-kernel@...r.kernel.org>,
netdev@...r.kernel.org
Subject: Re: [PATCH v3] Bluetooth: Add ncmd=0 recovery handling
Hi Manish,
> During command status or command complete event, the controller may set
> ncmd=0 indicating that it is not accepting any more commands. In such a
> case, host holds off sending any more commands to the controller. If the
> controller doesn't recover from such condition, host will wait forever,
> until the user decides that the Bluetooth is broken and may power cycles
> the Bluetooth.
>
> This patch triggers the hardware error to reset the controller and
> driver when it gets into such state as there is no other wat out.
>
> Reviewed-by: Abhishek Pandit-Subedi <abhishekpandit@...omium.org>
> Signed-off-by: Manish Mandlik <mmandlik@...gle.com>
> ---
>
> Changes in v3:
> - Restructure ncmd_timer scheduling in hci_event.c
> - Cancel delayed work in hci_dev_do_close
> - Do not inject hw error during HCI_INIT
> - Update comment, add log message while injecting hw error
>
> Changes in v2:
> - Emit the hardware error when ncmd=0 occurs
>
> include/net/bluetooth/hci.h | 1 +
> include/net/bluetooth/hci_core.h | 1 +
> net/bluetooth/hci_core.c | 22 ++++++++++++++++++++++
> net/bluetooth/hci_event.c | 22 ++++++++++++++++++----
> 4 files changed, 42 insertions(+), 4 deletions(-)
>
> diff --git a/include/net/bluetooth/hci.h b/include/net/bluetooth/hci.h
> index ea4ae551c426..c4b0650fb9ae 100644
> --- a/include/net/bluetooth/hci.h
> +++ b/include/net/bluetooth/hci.h
> @@ -339,6 +339,7 @@ enum {
> #define HCI_PAIRING_TIMEOUT msecs_to_jiffies(60000) /* 60 seconds */
> #define HCI_INIT_TIMEOUT msecs_to_jiffies(10000) /* 10 seconds */
> #define HCI_CMD_TIMEOUT msecs_to_jiffies(2000) /* 2 seconds */
> +#define HCI_NCMD_TIMEOUT msecs_to_jiffies(4000) /* 4 seconds */
> #define HCI_ACL_TX_TIMEOUT msecs_to_jiffies(45000) /* 45 seconds */
> #define HCI_AUTO_OFF_TIMEOUT msecs_to_jiffies(2000) /* 2 seconds */
> #define HCI_POWER_OFF_TIMEOUT msecs_to_jiffies(5000) /* 5 seconds */
> diff --git a/include/net/bluetooth/hci_core.h b/include/net/bluetooth/hci_core.h
> index ebdd4afe30d2..f14692b39fd5 100644
> --- a/include/net/bluetooth/hci_core.h
> +++ b/include/net/bluetooth/hci_core.h
> @@ -470,6 +470,7 @@ struct hci_dev {
> struct delayed_work service_cache;
>
> struct delayed_work cmd_timer;
> + struct delayed_work ncmd_timer;
>
> struct work_struct rx_work;
> struct work_struct cmd_work;
> diff --git a/net/bluetooth/hci_core.c b/net/bluetooth/hci_core.c
> index b0d9c36acc03..37789c5d0579 100644
> --- a/net/bluetooth/hci_core.c
> +++ b/net/bluetooth/hci_core.c
> @@ -1723,6 +1723,7 @@ int hci_dev_do_close(struct hci_dev *hdev)
> }
>
> cancel_delayed_work(&hdev->power_off);
> + cancel_delayed_work(&hdev->ncmd_timer);
>
> hci_request_cancel_all(hdev);
> hci_req_sync_lock(hdev);
> @@ -2769,6 +2770,24 @@ static void hci_cmd_timeout(struct work_struct *work)
> queue_work(hdev->workqueue, &hdev->cmd_work);
> }
>
> +/* HCI ncmd timer function */
> +static void hci_ncmd_timeout(struct work_struct *work)
> +{
> + struct hci_dev *hdev = container_of(work, struct hci_dev,
> + ncmd_timer.work);
> +
> + bt_dev_err(hdev, "Controller not accepting commands anymore: ncmd = 0");
> +
> + /* No hardware error event needs to be injected if the ncmd timer
> + * triggers during HCI_INIT.
> + */
while the patch looks good, I would be more strongly with my wording here.
/* During HCI_INIT phase no events can be injected if the ncmd timer
* triggers since the procedure has its own timeout handling.
*/
> + if (test_bit(HCI_INIT, &hdev->flags))
> + return;
> +
> + /* This is an irrecoverable state, inject hardware error event */
> + hci_reset_dev(hdev);
> +}
> +
> struct oob_data *hci_find_remote_oob_data(struct hci_dev *hdev,
> bdaddr_t *bdaddr, u8 bdaddr_type)
> {
> @@ -3831,6 +3850,7 @@ struct hci_dev *hci_alloc_dev(void)
> init_waitqueue_head(&hdev->suspend_wait_q);
>
> INIT_DELAYED_WORK(&hdev->cmd_timer, hci_cmd_timeout);
> + INIT_DELAYED_WORK(&hdev->ncmd_timer, hci_ncmd_timeout);
>
> hci_request_setup(hdev);
>
> @@ -4068,6 +4088,8 @@ int hci_reset_dev(struct hci_dev *hdev)
> hci_skb_pkt_type(skb) = HCI_EVENT_PKT;
> skb_put_data(skb, hw_err, 3);
>
> + bt_dev_err(hdev, "Injecting HCI hardware error event");
> +
> /* Send Hardware Error to upper stack */
> return hci_recv_frame(hdev, skb);
> }
> diff --git a/net/bluetooth/hci_event.c b/net/bluetooth/hci_event.c
> index cf2f4a0abdbd..8cd4bcf5dd00 100644
> --- a/net/bluetooth/hci_event.c
> +++ b/net/bluetooth/hci_event.c
> @@ -3635,8 +3635,15 @@ static void hci_cmd_complete_evt(struct hci_dev *hdev, struct sk_buff *skb,
> if (*opcode != HCI_OP_NOP)
> cancel_delayed_work(&hdev->cmd_timer);
>
> - if (ev->ncmd && !test_bit(HCI_RESET, &hdev->flags))
> - atomic_set(&hdev->cmd_cnt, 1);
> + if (!test_bit(HCI_RESET, &hdev->flags)) {
> + if (ev->ncmd) {
> + cancel_delayed_work(&hdev->ncmd_timer);
> + atomic_set(&hdev->cmd_cnt, 1);
> + } else {
> + schedule_delayed_work(&hdev->ncmd_timer,
> + HCI_NCMD_TIMEOUT);
> + }
> + }
>
> hci_req_cmd_complete(hdev, *opcode, *status, req_complete,
> req_complete_skb);
> @@ -3740,8 +3747,15 @@ static void hci_cmd_status_evt(struct hci_dev *hdev, struct sk_buff *skb,
> if (*opcode != HCI_OP_NOP)
> cancel_delayed_work(&hdev->cmd_timer);
>
> - if (ev->ncmd && !test_bit(HCI_RESET, &hdev->flags))
> - atomic_set(&hdev->cmd_cnt, 1);
> + if (!test_bit(HCI_RESET, &hdev->flags)) {
> + if (ev->ncmd) {
> + cancel_delayed_work(&hdev->ncmd_timer);
> + atomic_set(&hdev->cmd_cnt, 1);
> + } else {
> + schedule_delayed_work(&hdev->ncmd_timer,
> + HCI_NCMD_TIMEOUT);
> + }
> + }
>
Since the code is getting a bit more complex now, I would prefer that in a follow up patch we provide a common helper function for this.
static inline void handle_cmd_cnt_and_timer(struct hci_dev *hdev, bool is_nop)
{
if (!is_nop)
cancel_delayed_work(&hdev->cmd_timer);
if (!test_bit(HCI_RESET, ..) {
..
}
}
And then you can just do:
handle_cmd_cnt_and_timer(hdev, *opcode == HCI_OP_NOP);
Or something similar to this.
Regards
Marcel
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