Bluetooth: Add helper for serialized HCI command execution

The usage of __hci_cmd_sync() within the hdev->setup() callback allows for
a nice and simple serialized execution of HCI commands. More importantly
it allows for result processing before issueing the next command.

With the current usage of hci_req_run() it is possible to batch up
commands and execute them, but it is impossible to react to their
results or errors.

This is an attempt to generalize the hdev->setup() handling and provide
a simple way of running multiple HCI commands from a single function
context.

There are multiple struct work that are decdicated to certain tasks
already used right now. It is add a lot of bloat to hci_dev struct and
extra handling code. So it might be possible to put all of these behind
a common HCI command infrastructure and just execute the HCI commands
from the same work context in a serialized fashion.

For example updating the white list and resolving list can be done now
without having to know the list size ahead of time. Also preparing for
suspend or resume shouldn't require a state machine anymore. There are
other tasks that should be simplified as well.

Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>

1 files changed, 330 insertions, 0 deletions

diff --git a/net/bluetooth/hci_sync.c b/net/bluetooth/hci_sync.c
new file mode 100644
index 000000000000..b2048287fe90
--- /dev/null
+++ b/net/bluetooth/hci_sync.c
@@ -0,0 +1,330 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * BlueZ - Bluetooth protocol stack for Linux
+ *
+ * Copyright (C) 2021 Intel Corporation
+ */
+
+#include <net/bluetooth/bluetooth.h>
+#include <net/bluetooth/hci_core.h>
+#include <net/bluetooth/mgmt.h>
+
+#include "hci_request.h"
+#include "smp.h"
+
+static void hci_cmd_sync_complete(struct hci_dev *hdev, u8 result, u16 opcode,
+				  struct sk_buff *skb)
+{
+	bt_dev_dbg(hdev, "result 0x%2.2x", result);
+
+	if (hdev->req_status != HCI_REQ_PEND)
+		return;
+
+	hdev->req_result = result;
+	hdev->req_status = HCI_REQ_DONE;
+
+	wake_up_interruptible(&hdev->req_wait_q);
+}
+
+static struct sk_buff *hci_cmd_sync_alloc(struct hci_dev *hdev, u16 opcode,
+					  u32 plen, const void *param,
+					  struct sock *sk)
+{
+	int len = HCI_COMMAND_HDR_SIZE + plen;
+	struct hci_command_hdr *hdr;
+	struct sk_buff *skb;
+
+	skb = bt_skb_alloc(len, GFP_ATOMIC);
+	if (!skb)
+		return NULL;
+
+	hdr = skb_put(skb, HCI_COMMAND_HDR_SIZE);
+	hdr->opcode = cpu_to_le16(opcode);
+	hdr->plen   = plen;
+
+	if (plen)
+		skb_put_data(skb, param, plen);
+
+	bt_dev_dbg(hdev, "skb len %d", skb->len);
+
+	hci_skb_pkt_type(skb) = HCI_COMMAND_PKT;
+	hci_skb_opcode(skb) = opcode;
+
+	return skb;
+}
+
+static void hci_cmd_sync_add(struct hci_request *req, u16 opcode, u32 plen,
+			     const void *param, u8 event, struct sock *sk)
+{
+	struct hci_dev *hdev = req->hdev;
+	struct sk_buff *skb;
+
+	bt_dev_dbg(hdev, "opcode 0x%4.4x plen %d", opcode, plen);
+
+	/* If an error occurred during request building, there is no point in
+	 * queueing the HCI command. We can simply return.
+	 */
+	if (req->err)
+		return;
+
+	skb = hci_cmd_sync_alloc(hdev, opcode, plen, param, sk);
+	if (!skb) {
+		bt_dev_err(hdev, "no memory for command (opcode 0x%4.4x)",
+			   opcode);
+		req->err = -ENOMEM;
+		return;
+	}
+
+	if (skb_queue_empty(&req->cmd_q))
+		bt_cb(skb)->hci.req_flags |= HCI_REQ_START;
+
+	bt_cb(skb)->hci.req_event = event;
+
+	skb_queue_tail(&req->cmd_q, skb);
+}
+
+static int hci_cmd_sync_run(struct hci_request *req)
+{
+	struct hci_dev *hdev = req->hdev;
+	struct sk_buff *skb;
+	unsigned long flags;
+
+	bt_dev_dbg(hdev, "length %u", skb_queue_len(&req->cmd_q));
+
+	/* If an error occurred during request building, remove all HCI
+	 * commands queued on the HCI request queue.
+	 */
+	if (req->err) {
+		skb_queue_purge(&req->cmd_q);
+		return req->err;
+	}
+
+	/* Do not allow empty requests */
+	if (skb_queue_empty(&req->cmd_q))
+		return -ENODATA;
+
+	skb = skb_peek_tail(&req->cmd_q);
+	bt_cb(skb)->hci.req_complete_skb = hci_cmd_sync_complete;
+	bt_cb(skb)->hci.req_flags |= HCI_REQ_SKB;
+
+	spin_lock_irqsave(&hdev->cmd_q.lock, flags);
+	skb_queue_splice_tail(&req->cmd_q, &hdev->cmd_q);
+	spin_unlock_irqrestore(&hdev->cmd_q.lock, flags);
+
+	queue_work(hdev->workqueue, &hdev->cmd_work);
+
+	return 0;
+}
+
+/* This function requires the caller holds hdev->req_lock. */
+struct sk_buff *__hci_cmd_sync_sk(struct hci_dev *hdev, u16 opcode, u32 plen,
+				  const void *param, u8 event, u32 timeout,
+				  struct sock *sk)
+{
+	struct hci_request req;
+	struct sk_buff *skb;
+	int err = 0;
+
+	bt_dev_dbg(hdev, "");
+
+	hci_req_init(&req, hdev);
+
+	hci_cmd_sync_add(&req, opcode, plen, param, event, sk);
+
+	hdev->req_status = HCI_REQ_PEND;
+
+	err = hci_cmd_sync_run(&req);
+	if (err < 0)
+		return ERR_PTR(err);
+
+	err = wait_event_interruptible_timeout(hdev->req_wait_q,
+					       hdev->req_status != HCI_REQ_PEND,
+					       timeout);
+
+	if (err == -ERESTARTSYS)
+		return ERR_PTR(-EINTR);
+
+	switch (hdev->req_status) {
+	case HCI_REQ_DONE:
+		err = -bt_to_errno(hdev->req_result);
+		break;
+
+	case HCI_REQ_CANCELED:
+		err = -hdev->req_result;
+		break;
+
+	default:
+		err = -ETIMEDOUT;
+		break;
+	}
+
+	hdev->req_status = 0;
+	hdev->req_result = 0;
+	skb = hdev->req_skb;
+	hdev->req_skb = NULL;
+
+	bt_dev_dbg(hdev, "end: err %d", err);
+
+	if (err < 0) {
+		kfree_skb(skb);
+		return ERR_PTR(err);
+	}
+
+	if (!skb)
+		return ERR_PTR(-ENODATA);
+
+	return skb;
+}
+EXPORT_SYMBOL(__hci_cmd_sync_sk);
+
+/* This function requires the caller holds hdev->req_lock. */
+struct sk_buff *__hci_cmd_sync(struct hci_dev *hdev, u16 opcode, u32 plen,
+			       const void *param, u32 timeout)
+{
+	return __hci_cmd_sync_sk(hdev, opcode, plen, param, 0, timeout, NULL);
+}
+EXPORT_SYMBOL(__hci_cmd_sync);
+
+/* Send HCI command and wait for command complete event */
+struct sk_buff *hci_cmd_sync(struct hci_dev *hdev, u16 opcode, u32 plen,
+			     const void *param, u32 timeout)
+{
+	struct sk_buff *skb;
+
+	if (!test_bit(HCI_UP, &hdev->flags))
+		return ERR_PTR(-ENETDOWN);
+
+	bt_dev_dbg(hdev, "opcode 0x%4.4x plen %d", opcode, plen);
+
+	hci_req_sync_lock(hdev);
+	skb = __hci_cmd_sync(hdev, opcode, plen, param, timeout);
+	hci_req_sync_unlock(hdev);
+
+	return skb;
+}
+EXPORT_SYMBOL(hci_cmd_sync);
+
+/* This function requires the caller holds hdev->req_lock. */
+struct sk_buff *__hci_cmd_sync_ev(struct hci_dev *hdev, u16 opcode, u32 plen,
+				  const void *param, u8 event, u32 timeout)
+{
+	return __hci_cmd_sync_sk(hdev, opcode, plen, param, event, timeout,
+				 NULL);
+}
+EXPORT_SYMBOL(__hci_cmd_sync_ev);
+
+/* This function requires the caller holds hdev->req_lock. */
+int __hci_cmd_sync_status_sk(struct hci_dev *hdev, u16 opcode, u32 plen,
+			     const void *param, u8 event, u32 timeout,
+			     struct sock *sk)
+{
+	struct sk_buff *skb;
+	u8 status;
+
+	skb = __hci_cmd_sync_sk(hdev, opcode, plen, param, event, timeout, sk);
+	if (IS_ERR_OR_NULL(skb)) {
+		bt_dev_err(hdev, "Opcode 0x%4x failed: %ld", opcode,
+			   PTR_ERR(skb));
+		return PTR_ERR(skb);
+	}
+
+	status = skb->data[0];
+
+	kfree_skb(skb);
+
+	return status;
+}
+EXPORT_SYMBOL(__hci_cmd_sync_status_sk);
+
+int __hci_cmd_sync_status(struct hci_dev *hdev, u16 opcode, u32 plen,
+			  const void *param, u32 timeout)
+{
+	return __hci_cmd_sync_status_sk(hdev, opcode, plen, param, 0, timeout,
+					NULL);
+}
+EXPORT_SYMBOL(__hci_cmd_sync_status);
+
+static void hci_cmd_sync_work(struct work_struct *work)
+{
+	struct hci_dev *hdev = container_of(work, struct hci_dev, cmd_sync_work);
+	struct hci_cmd_sync_work_entry *entry;
+	hci_cmd_sync_work_func_t func;
+	hci_cmd_sync_work_destroy_t destroy;
+	void *data;
+
+	bt_dev_dbg(hdev, "");
+
+	mutex_lock(&hdev->cmd_sync_work_lock);
+	entry = list_first_entry(&hdev->cmd_sync_work_list,
+				 struct hci_cmd_sync_work_entry, list);
+	if (entry) {
+		list_del(&entry->list);
+		func = entry->func;
+		data = entry->data;
+		destroy = entry->destroy;
+		kfree(entry);
+	} else {
+		func = NULL;
+		data = NULL;
+		destroy = NULL;
+	}
+	mutex_unlock(&hdev->cmd_sync_work_lock);
+
+	if (func) {
+		int err;
+
+		hci_req_sync_lock(hdev);
+
+		err = func(hdev, data);
+
+		if (destroy)
+			destroy(hdev, data, err);
+
+		hci_req_sync_unlock(hdev);
+	}
+}
+
+void hci_cmd_sync_init(struct hci_dev *hdev)
+{
+	INIT_WORK(&hdev->cmd_sync_work, hci_cmd_sync_work);
+	INIT_LIST_HEAD(&hdev->cmd_sync_work_list);
+	mutex_init(&hdev->cmd_sync_work_lock);
+}
+
+void hci_cmd_sync_clear(struct hci_dev *hdev)
+{
+	struct hci_cmd_sync_work_entry *entry, *tmp;
+
+	cancel_work_sync(&hdev->cmd_sync_work);
+
+	list_for_each_entry_safe(entry, tmp, &hdev->cmd_sync_work_list, list) {
+		if (entry->destroy)
+			entry->destroy(hdev, entry->data, -ECANCELED);
+
+		list_del(&entry->list);
+		kfree(entry);
+	}
+}
+
+int hci_cmd_sync_queue(struct hci_dev *hdev, hci_cmd_sync_work_func_t func,
+		       void *data, hci_cmd_sync_work_destroy_t destroy)
+{
+	struct hci_cmd_sync_work_entry *entry;
+
+	entry = kmalloc(sizeof(*entry), GFP_KERNEL);
+	if (!entry)
+		return -ENOMEM;
+
+	entry->func = func;
+	entry->data = data;
+	entry->destroy = destroy;
+
+	mutex_lock(&hdev->cmd_sync_work_lock);
+	list_add_tail(&entry->list, &hdev->cmd_sync_work_list);
+	mutex_unlock(&hdev->cmd_sync_work_lock);
+
+	queue_work(hdev->req_workqueue, &hdev->cmd_sync_work);
+
+	return 0;
+}
+EXPORT_SYMBOL(hci_cmd_sync_queue);