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Date: Tue, 4 Feb 2020 15:10:07 -0800
From: Abhishek Pandit-Subedi <abhishekpandit@...omium.org>
To: Venkata Lakshmi Narayana Gubba <gubbaven@...eaurora.org>
Cc: Marcel Holtmann <marcel@...tmann.org>,
Johan Hedberg <johan.hedberg@...il.com>,
Matthias Kaehlcke <mka@...omium.org>,
LKML <linux-kernel@...r.kernel.org>,
Bluez mailing list <linux-bluetooth@...r.kernel.org>,
robh@...nel.org, hemantg@...eaurora.org,
linux-arm-msm@...r.kernel.org, bgodavar@...eaurora.org,
tientzu@...omium.org, seanpaul@...omium.org, rjliao@...eaurora.org,
Yoni Shavit <yshavit@...gle.com>
Subject: Re: [PATCH v1] Bluetooth: hci_qca: Bug fixes while collecting
controller memory dump
Hi Venkata,
Per our earlier review on chromium gerrit:
https://chromium-review.googlesource.com/c/chromiumos/third_party/kernel/+/1992966
I'm not too keen on the change from mutex to spinlock because it's
made the code more complex.
Also, it has been a couple weeks since my last review and I've lost
the context of what order of events are supposed to happen (making
reviewing the sequencing hard).
Good case:
Memdump event from firmware
Some number of memdump events with seq #
Hw error event
Reset
Timeout case:
Memdump event from firmware
Some number of memdump events with seq #
Timeout schedules hw_error_event
hw_error_event clears the memdump activity
reset
Software memdump:
hw_error_event sends memdump command to firmware and waits for completion
memdump event with seq#
hw error event
reset
Does this look right? Could you add this to either the commit message
or as a comment in one of the functions so that it's easier to
understand what is the expected order of events.
On Tue, Feb 4, 2020 at 8:16 AM Venkata Lakshmi Narayana Gubba
<gubbaven@...eaurora.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.
>
> Fixes: d841502c79e3 ("Bluetooth: hci_qca: Collect controller memory dump during SSR")
> Reported-by: Abhishek Pandit-Subedi <abhishekpandit@...omium.org>
> Signed-off-by: Venkata Lakshmi Narayana Gubba <gubbaven@...eaurora.org>
> ---
> drivers/bluetooth/hci_qca.c | 104 ++++++++++++++++++++++++++++++++++++++------
> 1 file changed, 90 insertions(+), 14 deletions(-)
>
> diff --git a/drivers/bluetooth/hci_qca.c b/drivers/bluetooth/hci_qca.c
> index eacc65b..ea956c3 100644
> --- a/drivers/bluetooth/hci_qca.c
> +++ b/drivers/bluetooth/hci_qca.c
> @@ -69,7 +69,8 @@ enum qca_flags {
> QCA_IBS_ENABLED,
> QCA_DROP_VENDOR_EVENT,
> QCA_SUSPENDING,
> - QCA_MEMDUMP_COLLECTION
> + QCA_MEMDUMP_COLLECTION,
> + QCA_HW_ERROR_EVENT
> };
>
>
> @@ -150,6 +151,7 @@ struct qca_data {
> struct completion drop_ev_comp;
> wait_queue_head_t suspend_wait_q;
> enum qca_memdump_states memdump_state;
> + spinlock_t hci_memdump_lock;
In an earlier revision of this patch, you had this lock as a mutex.
Why change it from mutex to spinlock_t? I think this has made your
change more complex since you have to unlock during the middle of an
operation more often (i.e. since it can block)
>
> /* For debugging purpose */
> u64 ibs_sent_wacks;
> @@ -524,19 +526,19 @@ 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 qca_data *qca = from_timer(qca, t, memdump_timer);
> struct hci_uart *hu = qca->hu;
> - struct qca_memdump_data *qca_memdump = qca->qca_memdump;
> - char *memdump_buf = qca_memdump->memdump_buf_tail;
> + unsigned long flags;
>
> - 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);
> + spin_lock_irqsave(&qca->hci_memdump_lock, 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);
> + }
> +
> del_timer(&qca->memdump_timer);
> - cancel_work_sync(&qca->ctrl_memdump_evt);
> + spin_unlock_irqrestore(&qca->hci_memdump_lock, flags);
Missing cancel_work_sync (not sure if intentional but it's included in
qca_wait_for_dump_collection so it should probably be here too)
> }
>
> /* Initialize protocol */
> @@ -558,6 +560,7 @@ 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);
> + spin_lock_init(&qca->hci_memdump_lock);
> qca->workqueue = alloc_ordered_workqueue("qca_wq", 0);
> if (!qca->workqueue) {
> BT_ERR("QCA Workqueue not initialized properly");
> @@ -960,14 +963,25 @@ static void qca_controller_memdump(struct work_struct *work)
> char nullBuff[QCA_DUMP_PACKET_SIZE] = { 0 };
> u16 seq_no;
> u32 dump_size;
> + unsigned long flags;
>
> while ((skb = skb_dequeue(&qca->rx_memdump_q))) {
>
> + spin_lock_irqsave(&qca->hci_memdump_lock, flags);
> + /* Skip processing the received packets if timeout detected. */
> + if (qca->memdump_state == QCA_MEMDUMP_TIMEOUT) {
> + spin_unlock_irqrestore(&qca->hci_memdump_lock, flags);
> + return;
> + }
> +
> if (!qca_memdump) {
> qca_memdump = kzalloc(sizeof(struct qca_memdump_data),
> GFP_ATOMIC);
> - if (!qca_memdump)
> + if (!qca_memdump) {
> + spin_unlock_irqrestore(&qca->hci_memdump_lock,
> + flags);
> return;
> + }
>
> qca->qca_memdump = qca_memdump;
> }
> @@ -992,6 +1006,8 @@ static void qca_controller_memdump(struct work_struct *work)
> if (!(dump_size)) {
> bt_dev_err(hu->hdev, "Rx invalid memdump size");
> kfree_skb(skb);
> + spin_unlock_irqrestore(&qca->hci_memdump_lock,
> + flags);
> return;
> }
>
> @@ -1001,7 +1017,24 @@ static void qca_controller_memdump(struct work_struct *work)
> msecs_to_jiffies(MEMDUMP_TIMEOUT_MS)));
>
> skb_pull(skb, sizeof(dump_size));
> +
> + /* vmalloc() might go to sleep while trying to allocate
> + * memory.As calling sleep function under spin lock is
> + * not allowed so unlocking spin lock and will be locked
> + * again after vmalloc().
> + */
> + spin_unlock_irqrestore(&qca->hci_memdump_lock, flags);
> memdump_buf = vmalloc(dump_size);
> + spin_lock_irqsave(&qca->hci_memdump_lock, flags);
> + /* Skip processing the received packets if timeout
> + * detected.
> + */
> + if (qca->memdump_state == QCA_MEMDUMP_TIMEOUT) {
> + spin_unlock_irqrestore(&qca->hci_memdump_lock,
> + flags);
> + return;
> + }
> +
> qca_memdump->memdump_buf_head = memdump_buf;
> qca_memdump->memdump_buf_tail = memdump_buf;
> }
> @@ -1016,6 +1049,7 @@ static void qca_controller_memdump(struct work_struct *work)
> kfree(qca_memdump);
> kfree_skb(skb);
> qca->qca_memdump = NULL;
> + spin_unlock_irqrestore(&qca->hci_memdump_lock, flags);
> return;
> }
>
> @@ -1044,18 +1078,37 @@ static void qca_controller_memdump(struct work_struct *work)
> bt_dev_info(hu->hdev, "QCA writing crash dump of size %d bytes",
> qca_memdump->received_dump);
> memdump_buf = qca_memdump->memdump_buf_head;
> +
> + /* dev_coredumpv() might go to sleep.As calling sleep
> + * function under spin lock is not allowed so unlocking
> + * spin lock and will be locked again after
> + * dev_coredumpv().
> + */
> + spin_unlock_irqrestore(&qca->hci_memdump_lock,
> + flags);
> dev_coredumpv(&hu->serdev->dev, memdump_buf,
> qca_memdump->received_dump, GFP_KERNEL);
> + spin_lock_irqsave(&qca->hci_memdump_lock, flags);
> + if (qca->memdump_state == QCA_MEMDUMP_TIMEOUT) {
> + spin_unlock_irqrestore(&qca->hci_memdump_lock,
> + flags);
> + return;
> + }
> +
> del_timer(&qca->memdump_timer);
> kfree(qca->qca_memdump);
> qca->qca_memdump = NULL;
> qca->memdump_state = QCA_MEMDUMP_COLLECTED;
> + clear_bit(QCA_MEMDUMP_COLLECTION, &qca->flags);
> }
> +
> + spin_unlock_irqrestore(&qca->hci_memdump_lock, flags);
> }
>
> }
>
> -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;
> @@ -1408,19 +1461,25 @@ static void qca_wait_for_dump_collection(struct hci_dev *hdev)
> struct qca_data *qca = hu->priv;
> struct qca_memdump_data *qca_memdump = qca->qca_memdump;
> char *memdump_buf = NULL;
> + unsigned long flags;
>
> 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) {
> + if (qca->memdump_state == QCA_MEMDUMP_IDLE ||
> + qca->memdump_state == QCA_MEMDUMP_COLLECTING) {
> bt_dev_err(hu->hdev, "Clearing the buffers due to timeout");
> + spin_lock_irqsave(&qca->hci_memdump_lock, flags);
> if (qca_memdump)
> - memdump_buf = qca_memdump->memdump_buf_tail;
> + 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);
> + spin_unlock_irqrestore(&qca->hci_memdump_lock, flags);
> cancel_work_sync(&qca->ctrl_memdump_evt);
> }
> }
> @@ -1429,7 +1488,11 @@ 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;
> + unsigned long flags;
>
> + 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) {
> @@ -1448,7 +1511,20 @@ 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);
> + } else if (qca->memdump_state == QCA_MEMDUMP_TIMEOUT) {
> + bt_dev_err(hu->hdev, "clearing allocated memory due to memdump timeout");
> + spin_lock_irqsave(&qca->hci_memdump_lock, flags);
> + if (qca_memdump)
> + memdump_buf = qca_memdump->memdump_buf_head;
> + vfree(memdump_buf);
> + kfree(qca_memdump);
> + qca->qca_memdump = NULL;
> + skb_queue_purge(&qca->rx_memdump_q);
> + spin_unlock_irqrestore(&qca->hci_memdump_lock, flags);
> + 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
>
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