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Date:   Thu, 13 Feb 2020 21:26:04 +0530
From:   Venkata Lakshmi Narayana Gubba <gubbaven@...eaurora.org>
To:     marcel@...tmann.org, johan.hedberg@...il.com
Cc:     mka@...omium.org, linux-kernel@...r.kernel.org,
        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, yshavit@...gle.com,
        Venkata Lakshmi Narayana Gubba <gubbaven@...eaurora.org>
Subject: [PATCH v3] Bluetooth: hci_qca: Bug fixes while collecting controller memory dump

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@...omium.org>
Signed-off-by: Venkata Lakshmi Narayana Gubba <gubbaven@...eaurora.org>
---
v3:
  * Removed memdump_timer completely.
  * Used delayed work queue.
--- 
 drivers/bluetooth/hci_qca.c | 101 +++++++++++++++++++++++++++++---------------
 1 file changed, 67 insertions(+), 34 deletions(-)

diff --git a/drivers/bluetooth/hci_qca.c b/drivers/bluetooth/hci_qca.c
index eacc65b..9cae5fe 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
 };
 
 
@@ -138,18 +140,19 @@ struct qca_data {
 	u32 tx_idle_delay;
 	struct timer_list wake_retrans_timer;
 	u32 wake_retrans;
-	struct timer_list memdump_timer;
 	struct workqueue_struct *workqueue;
 	struct work_struct ws_awake_rx;
 	struct work_struct ws_awake_device;
 	struct work_struct ws_rx_vote_off;
 	struct work_struct ws_tx_vote_off;
 	struct work_struct ctrl_memdump_evt;
+	struct delayed_work 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;
@@ -522,23 +525,28 @@ static void hci_ibs_wake_retrans_timeout(struct timer_list *t)
 		hci_uart_tx_wakeup(hu);
 }
 
-static void hci_memdump_timeout(struct timer_list *t)
+
+static void qca_controller_memdump_timeout(struct work_struct *work)
 {
-	struct qca_data *qca = from_timer(qca, t, tx_idle_timer);
+	struct qca_data *qca = container_of(work, struct qca_data,
+					ctrl_memdump_timeout.work);
 	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;
-	del_timer(&qca->memdump_timer);
-	cancel_work_sync(&qca->ctrl_memdump_evt);
+
+	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 +566,7 @@ 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 +579,8 @@ 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_DELAYED_WORK(&qca->ctrl_memdump_timeout,
+			  qca_controller_memdump_timeout);
 	init_waitqueue_head(&qca->suspend_wait_q);
 
 	qca->hu = hu;
@@ -596,7 +607,6 @@ static int qca_open(struct hci_uart *hu)
 
 	timer_setup(&qca->tx_idle_timer, hci_ibs_tx_idle_timeout, 0);
 	qca->tx_idle_delay = IBS_HOST_TX_IDLE_TIMEOUT_MS;
-	timer_setup(&qca->memdump_timer, hci_memdump_timeout, 0);
 
 	BT_DBG("HCI_UART_QCA open, tx_idle_delay=%u, wake_retrans=%u",
 	       qca->tx_idle_delay, qca->wake_retrans);
@@ -677,7 +687,6 @@ static int qca_close(struct hci_uart *hu)
 	skb_queue_purge(&qca->rx_memdump_q);
 	del_timer(&qca->tx_idle_timer);
 	del_timer(&qca->wake_retrans_timer);
-	del_timer(&qca->memdump_timer);
 	destroy_workqueue(qca->workqueue);
 	qca->hu = NULL;
 
@@ -963,11 +972,20 @@ 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;
 		}
@@ -992,13 +1010,15 @@ 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;
 			}
 
 			bt_dev_info(hu->hdev, "QCA collecting dump of size:%u",
 				    dump_size);
-			mod_timer(&qca->memdump_timer, (jiffies +
-				  msecs_to_jiffies(MEMDUMP_TIMEOUT_MS)));
+			queue_delayed_work(qca->workqueue,
+					   &qca->ctrl_memdump_timeout,
+					msecs_to_jiffies(MEMDUMP_TIMEOUT_MS));
 
 			skb_pull(skb, sizeof(dump_size));
 			memdump_buf = vmalloc(dump_size);
@@ -1016,6 +1036,7 @@ 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;
 		}
 
@@ -1046,16 +1067,20 @@ static void qca_controller_memdump(struct work_struct *work)
 			memdump_buf = qca_memdump->memdump_buf_head;
 			dev_coredumpv(&hu->serdev->dev, memdump_buf,
 				      qca_memdump->received_dump, GFP_KERNEL);
-			del_timer(&qca->memdump_timer);
+			cancel_delayed_work(&qca->ctrl_memdump_timeout);
 			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 +1431,21 @@ 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 +1465,23 @@ 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;
+		cancel_delayed_work(&qca->ctrl_memdump_timeout);
+		skb_queue_purge(&qca->rx_memdump_q);
+		mutex_unlock(&qca->hci_memdump_lock);
+		cancel_work_sync(&qca->ctrl_memdump_evt);
+	}
+
+	clear_bit(QCA_HW_ERROR_EVENT, &qca->flags);
 }
 
 static void qca_cmd_timeout(struct hci_dev *hdev)
-- 
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