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SubjectRe: [PATCH v2] Bluetooth: hci_qca: Bug fixes while collecting controller memory dump
Hi Venkata,

I would suggest removing the memdump_timer entirely and making the
ctrl_memdump_timeout into struct delayed_work.

Instead of using mod_timer to get the callback ready, you would
instead call `queue_delayed_work(qca->workqueue,
&qca->ctrl_memdump_timeout, MEMDUMP_TIMEOUT_MS);` and instead of
del_timer, you would instead
`cancel_delayed_work(&qca->ctrl_memdump_timeout)` if mutex is held or
`cancel_delayed_work_sync(&qca->ctrl_memdump_timeout)` if mutex is not
held.

Other than that, everything else looks good to me.

On Wed, Feb 12, 2020 at 7:51 AM Venkata Lakshmi Narayana Gubba
<gubbaven@codeaurora.org> wrote:
>
> This patch will fix the below issues
> 1.Fixed race conditions while accessing memory dump state flags.
> 2.Updated with actual context of timer in hci_memdump_timeout()
> 3.Updated injecting hardware error event if the dumps failed to receive.
> 4.Once timeout is triggered, stopping the memory dump collections.
>
> Possible scenarios while collecting memory dump:
>
> Scenario 1:
>
> Memdump event from firmware
> Some number of memdump events with seq #
> Hw error event
> Reset
>
> Scenario 2:
>
> Memdump event from firmware
> Some number of memdump events with seq #
> Timeout schedules hw_error_event if hw error event is not received already
> hw_error_event clears the memdump activity
> reset
>
> Scenario 3:
>
> hw_error_event sends memdump command to firmware and waits for completion
> Some number of memdump events with seq #
> hw error event
> reset
>
> Fixes: d841502c79e3 ("Bluetooth: hci_qca: Collect controller memory dump during SSR")
> Reported-by: Abhishek Pandit-Subedi <abhishekpandit@chromium.org>
> Signed-off-by: Venkata Lakshmi Narayana Gubba <gubbaven@codeaurora.org>
> ---
> drivers/bluetooth/hci_qca.c | 96 ++++++++++++++++++++++++++++++++-------------
> 1 file changed, 69 insertions(+), 27 deletions(-)
>
> diff --git a/drivers/bluetooth/hci_qca.c b/drivers/bluetooth/hci_qca.c
> index eacc65b..80ee838 100644
> --- a/drivers/bluetooth/hci_qca.c
> +++ b/drivers/bluetooth/hci_qca.c
> @@ -29,6 +29,7 @@
> #include <linux/platform_device.h>
> #include <linux/regulator/consumer.h>
> #include <linux/serdev.h>
> +#include <linux/mutex.h>
> #include <asm/unaligned.h>
>
> #include <net/bluetooth/bluetooth.h>
> @@ -69,7 +70,8 @@ enum qca_flags {
> QCA_IBS_ENABLED,
> QCA_DROP_VENDOR_EVENT,
> QCA_SUSPENDING,
> - QCA_MEMDUMP_COLLECTION
> + QCA_MEMDUMP_COLLECTION,
> + QCA_HW_ERROR_EVENT
> };
>
>
> @@ -145,11 +147,13 @@ struct qca_data {
> struct work_struct ws_rx_vote_off;
> struct work_struct ws_tx_vote_off;
> struct work_struct ctrl_memdump_evt;
> + struct work_struct ctrl_memdump_timeout;
> struct qca_memdump_data *qca_memdump;
> unsigned long flags;
> struct completion drop_ev_comp;
> wait_queue_head_t suspend_wait_q;
> enum qca_memdump_states memdump_state;
> + struct mutex hci_memdump_lock;
>
> /* For debugging purpose */
> u64 ibs_sent_wacks;
> @@ -524,21 +528,33 @@ static void hci_ibs_wake_retrans_timeout(struct timer_list *t)
>
> static void hci_memdump_timeout(struct timer_list *t)
> {
> - struct qca_data *qca = from_timer(qca, t, tx_idle_timer);
> - struct hci_uart *hu = qca->hu;
> - struct qca_memdump_data *qca_memdump = qca->qca_memdump;
> - char *memdump_buf = qca_memdump->memdump_buf_tail;
> -
> - bt_dev_err(hu->hdev, "clearing allocated memory due to memdump timeout");
> - /* Inject hw error event to reset the device and driver. */
> - hci_reset_dev(hu->hdev);
> - vfree(memdump_buf);
> - kfree(qca_memdump);
> - qca->memdump_state = QCA_MEMDUMP_TIMEOUT;
> + struct qca_data *qca = from_timer(qca, t, memdump_timer);
> +
> + queue_work(qca->workqueue, &qca->ctrl_memdump_timeout);
> del_timer(&qca->memdump_timer);
> - cancel_work_sync(&qca->ctrl_memdump_evt);
> }
>
> +static void qca_controller_memdump_timeout(struct work_struct *work)
> +{
> + struct qca_data *qca = container_of(work, struct qca_data,
> + ctrl_memdump_timeout);
> + struct hci_uart *hu = qca->hu;
> +
> + mutex_lock(&qca->hci_memdump_lock);
> + if (test_bit(QCA_MEMDUMP_COLLECTION, &qca->flags)) {
> + qca->memdump_state = QCA_MEMDUMP_TIMEOUT;
> + if (!test_bit(QCA_HW_ERROR_EVENT, &qca->flags)) {
> + /* Inject hw error event to reset the device
> + * and driver.
> + */
> + hci_reset_dev(hu->hdev);
> + }
> + }
> +
> + mutex_unlock(&qca->hci_memdump_lock);
> +}
> +
> +
> /* Initialize protocol */
> static int qca_open(struct hci_uart *hu)
> {
> @@ -558,6 +574,7 @@ static int qca_open(struct hci_uart *hu)
> skb_queue_head_init(&qca->tx_wait_q);
> skb_queue_head_init(&qca->rx_memdump_q);
> spin_lock_init(&qca->hci_ibs_lock);
> + mutex_init(&qca->hci_memdump_lock);
> qca->workqueue = alloc_ordered_workqueue("qca_wq", 0);
> if (!qca->workqueue) {
> BT_ERR("QCA Workqueue not initialized properly");
> @@ -570,6 +587,7 @@ static int qca_open(struct hci_uart *hu)
> INIT_WORK(&qca->ws_rx_vote_off, qca_wq_serial_rx_clock_vote_off);
> INIT_WORK(&qca->ws_tx_vote_off, qca_wq_serial_tx_clock_vote_off);
> INIT_WORK(&qca->ctrl_memdump_evt, qca_controller_memdump);
> + INIT_WORK(&qca->ctrl_memdump_timeout, qca_controller_memdump_timeout);
> init_waitqueue_head(&qca->suspend_wait_q);
>
> qca->hu = hu;
> @@ -963,11 +981,20 @@ static void qca_controller_memdump(struct work_struct *work)
>
> while ((skb = skb_dequeue(&qca->rx_memdump_q))) {
>
> + mutex_lock(&qca->hci_memdump_lock);
> + /* Skip processing the received packets if timeout detected. */
> + if (qca->memdump_state == QCA_MEMDUMP_TIMEOUT) {
> + mutex_unlock(&qca->hci_memdump_lock);
> + return;
> + }
> +
> if (!qca_memdump) {
> qca_memdump = kzalloc(sizeof(struct qca_memdump_data),
> GFP_ATOMIC);
> - if (!qca_memdump)
> + if (!qca_memdump) {
> + mutex_unlock(&qca->hci_memdump_lock);
> return;
> + }
>
> qca->qca_memdump = qca_memdump;
> }
> @@ -992,6 +1019,7 @@ static void qca_controller_memdump(struct work_struct *work)
> if (!(dump_size)) {
> bt_dev_err(hu->hdev, "Rx invalid memdump size");
> kfree_skb(skb);
> + mutex_unlock(&qca->hci_memdump_lock);
> return;
> }
>
> @@ -1016,6 +1044,7 @@ static void qca_controller_memdump(struct work_struct *work)
> kfree(qca_memdump);
> kfree_skb(skb);
> qca->qca_memdump = NULL;
> + mutex_unlock(&qca->hci_memdump_lock);
> return;
> }
>
> @@ -1050,12 +1079,16 @@ static void qca_controller_memdump(struct work_struct *work)
> kfree(qca->qca_memdump);
> qca->qca_memdump = NULL;
> qca->memdump_state = QCA_MEMDUMP_COLLECTED;
> + clear_bit(QCA_MEMDUMP_COLLECTION, &qca->flags);
> }
> +
> + mutex_unlock(&qca->hci_memdump_lock);
> }
>
> }
>
> -int qca_controller_memdump_event(struct hci_dev *hdev, struct sk_buff *skb)
> +static int qca_controller_memdump_event(struct hci_dev *hdev,
> + struct sk_buff *skb)
> {
> struct hci_uart *hu = hci_get_drvdata(hdev);
> struct qca_data *qca = hu->priv;
> @@ -1406,30 +1439,21 @@ static void qca_wait_for_dump_collection(struct hci_dev *hdev)
> {
> struct hci_uart *hu = hci_get_drvdata(hdev);
> struct qca_data *qca = hu->priv;
> - struct qca_memdump_data *qca_memdump = qca->qca_memdump;
> - char *memdump_buf = NULL;
>
> wait_on_bit_timeout(&qca->flags, QCA_MEMDUMP_COLLECTION,
> TASK_UNINTERRUPTIBLE, MEMDUMP_TIMEOUT_MS);
>
> clear_bit(QCA_MEMDUMP_COLLECTION, &qca->flags);
> - if (qca->memdump_state == QCA_MEMDUMP_IDLE) {
> - bt_dev_err(hu->hdev, "Clearing the buffers due to timeout");
> - if (qca_memdump)
> - memdump_buf = qca_memdump->memdump_buf_tail;
> - vfree(memdump_buf);
> - kfree(qca_memdump);
> - qca->memdump_state = QCA_MEMDUMP_TIMEOUT;
> - del_timer(&qca->memdump_timer);
> - cancel_work_sync(&qca->ctrl_memdump_evt);
> - }
> }
>
> static void qca_hw_error(struct hci_dev *hdev, u8 code)
> {
> struct hci_uart *hu = hci_get_drvdata(hdev);
> struct qca_data *qca = hu->priv;
> + struct qca_memdump_data *qca_memdump = qca->qca_memdump;
> + char *memdump_buf = NULL;
>
> + set_bit(QCA_HW_ERROR_EVENT, &qca->flags);
> bt_dev_info(hdev, "mem_dump_status: %d", qca->memdump_state);
>
> if (qca->memdump_state == QCA_MEMDUMP_IDLE) {
> @@ -1449,6 +1473,24 @@ static void qca_hw_error(struct hci_dev *hdev, u8 code)
> bt_dev_info(hdev, "waiting for dump to complete");
> qca_wait_for_dump_collection(hdev);
> }
> +
> + if (qca->memdump_state != QCA_MEMDUMP_COLLECTED) {
> + bt_dev_err(hu->hdev, "clearing allocated memory due to memdump timeout");
> + mutex_lock(&qca->hci_memdump_lock);
> + if (qca_memdump)
> + memdump_buf = qca_memdump->memdump_buf_head;
> + vfree(memdump_buf);
> + kfree(qca_memdump);
> + qca->qca_memdump = NULL;
> + qca->memdump_state = QCA_MEMDUMP_TIMEOUT;
> + del_timer(&qca->memdump_timer);
> + skb_queue_purge(&qca->rx_memdump_q);
> + mutex_unlock(&qca->hci_memdump_lock);
> + cancel_work_sync(&qca->ctrl_memdump_timeout);
> + cancel_work_sync(&qca->ctrl_memdump_evt);
> + }
> +
> + clear_bit(QCA_HW_ERROR_EVENT, &qca->flags);
> }
>
> static void qca_cmd_timeout(struct hci_dev *hdev)
> --
> QUALCOMM INDIA, on behalf of Qualcomm Innovation Center, Inc. is a member
> of Code Aurora Forum, hosted by The Linux Foundation
>

Thanks
Abhishek

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