RE: [PATCH v11 01/10] Bluetooth: Enumerate local supported codec and cache details

Hi Marcel,

-----Original Message-----
From: Marcel Holtmann <marcel@holtmann.org>
Sent: Friday, July 30, 2021 7:36 PM
To: K, Kiran <redacted>
Cc: BlueZ <redacted>; Srivatsa, Ravishankar
[off-list ref]; Tumkur Narayan, Chethan
[off-list ref]
Subject: Re: [PATCH v11 01/10] Bluetooth: Enumerate local supported codec
and cache details

Hi Kiran,

quoted

Move reading of supported local codecs into a separate init function,
query codecs capabilities and cache the data

Signed-off-by: Kiran K <redacted>
Signed-off-by: Chethan T N <redacted>
Signed-off-by: Srivatsa Ravishankar <redacted>
---
* changes in v11:
- Remove Kconfig related changes
- Address minor review comments
- Move codec related functions to new file hci_codec.c

* changes in v10:
- define Kconfig to control offload feature at build time
- fix review comments

* changes in v9:
 - use shortname vnd instead of ven

* changes in v8:
 - add comments
 - split __u8 codec_id[5] into {__u8 id; __le16 cid, vid }
 - address review comment related codec caps structure

* changes in v7:
 - keep codec enumeration call in hci_init instead of having a separate
   function
 - Remove unused bitmasks defined for LE transports

* changes  in v6:
 - fix compiler warning reported for ARCH=arc

* changes in v5:
 - fix review comments
 - move code used to read standard/vendor codecs caps into single
function

* changes in v4:
 - convert  reading of codecs and codecs caps calls from async to sync

* changes in v3
 move codec enumeration into a new init function

* changes in v2
 add skb length check before accessing data

include/net/bluetooth/hci.h      |  41 +++++++
include/net/bluetooth/hci_core.h |  17 +++
net/bluetooth/Makefile           |   2 +-
net/bluetooth/hci_codec.c        | 194 +++++++++++++++++++++++++++++++
net/bluetooth/hci_codec.h        |   6 +
net/bluetooth/hci_core.c         |  12 +-
6 files changed, 266 insertions(+), 6 deletions(-) create mode 100644
net/bluetooth/hci_codec.c create mode 100644 net/bluetooth/hci_codec.h

diff --git a/include/net/bluetooth/hci.h b/include/net/bluetooth/hci.h
index b80415011dcd..f76849c8eafd 100644
--- a/include/net/bluetooth/hci.h
+++ b/include/net/bluetooth/hci.h

@@ -1307,6 +1307,28 @@ struct hci_rp_read_data_block_size { }

__packed;

#define HCI_OP_READ_LOCAL_CODECS	0x100b
+struct hci_std_codecs {
+	__u8	num;
+	__u8	codec[];
+} __packed;
+
+struct hci_vnd_codec {
+	/* company id */
+	__le16	cid;
+	/* vendor codec id */
+	__le16	vid;
+} __packed;
+
+struct hci_vnd_codecs {
+	__u8	num;
+	struct hci_vnd_codec codec[];
+} __packed;
+
+struct hci_rp_read_local_supported_codecs {
+	__u8	status;
+	struct hci_std_codecs std_codecs;
+	struct hci_vnd_codecs vnd_codecs;
+} __packed;

#define HCI_OP_READ_LOCAL_PAIRING_OPTS	0x100c
struct hci_rp_read_local_pairing_opts { @@ -1315,6 +1337,25 @@ struct
hci_rp_read_local_pairing_opts {
	__u8     max_key_size;
} __packed;

+#define HCI_OP_READ_LOCAL_CODEC_CAPS	0x100e
+struct hci_op_read_local_codec_caps {
+	__u8	id;
+	__le16	cid;
+	__le16	vid;
+	__u8	transport;
+	__u8	direction;
+} __packed;
+
+struct hci_codec_caps {
+	__u8	len;
+	__u8	data[];
+} __packed;
+
+struct hci_rp_read_local_codec_caps {
+	__u8	status;
+	__u8	num_caps;
+} __packed;
+
#define HCI_OP_READ_PAGE_SCAN_ACTIVITY	0x0c1b
struct hci_rp_read_page_scan_activity {
	__u8     status;

diff --git a/include/net/bluetooth/hci_core.h

b/include/net/bluetooth/hci_core.h
index a53e94459ecd..6742e6ad7b37 100644

--- a/include/net/bluetooth/hci_core.h
+++ b/include/net/bluetooth/hci_core.h

@@ -131,6 +131,17 @@ struct bdaddr_list {

	u8 bdaddr_type;
};

+struct codec_list {
+	struct list_head list;
+	u8	id;
+	__u16	cid;
+	__u16	vid;
+	u8	transport;
+	u8	num_caps;
+	u32	len;
+	struct hci_codec_caps caps[];
+};
+
struct bdaddr_list_with_irk {
	struct list_head list;
	bdaddr_t bdaddr;

@@ -535,6 +546,7 @@ struct hci_dev {

	struct list_head	pend_le_conns;
	struct list_head	pend_le_reports;
	struct list_head	blocked_keys;
+	struct list_head	local_codecs;

	struct hci_dev_stats	stat;

@@ -1849,4 +1861,9 @@ void hci_copy_identity_address(struct hci_dev

*hdev, bdaddr_t *bdaddr,

quoted

#define SCO_AIRMODE_CVSD       0x0000
#define SCO_AIRMODE_TRANSP     0x0003

+#define LOCAL_CODEC_ACL_MASK	BIT(0)
+#define LOCAL_CODEC_SCO_MASK	BIT(1)
+
+#define TRANSPORT_TYPE_MAX	0x04
+
#endif /* __HCI_CORE_H */

diff --git a/net/bluetooth/Makefile b/net/bluetooth/Makefile index

cc0995301f93..f3e439d98b85 100644

--- a/net/bluetooth/Makefile
+++ b/net/bluetooth/Makefile

@@ -14,7 +14,7 @@ bluetooth_6lowpan-y := 6lowpan.o

bluetooth-y := af_bluetooth.o hci_core.o hci_conn.o hci_event.o mgmt.o \
	hci_sock.o hci_sysfs.o l2cap_core.o l2cap_sock.o smp.o lib.o \
-	ecdh_helper.o hci_request.o mgmt_util.o mgmt_config.o
+	ecdh_helper.o hci_request.o mgmt_util.o mgmt_config.o hci_codec.o

bluetooth-$(CONFIG_BT_BREDR) += sco.o
bluetooth-$(CONFIG_BT_HS) += a2mp.o amp.o diff --git
a/net/bluetooth/hci_codec.c b/net/bluetooth/hci_codec.c new file mode
100644 index 000000000000..205f3b04c172

--- /dev/null
+++ b/net/bluetooth/hci_codec.c

@@ -0,0 +1,194 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (C) 2021 Intel Corporation */
+
+#include <net/bluetooth/bluetooth.h>
+#include <net/bluetooth/hci_core.h>
+
+static int hci_codec_list_add(struct list_head *list,
+			      struct hci_op_read_local_codec_caps *sent,
+			      struct hci_rp_read_local_codec_caps *rp,
+			      void *caps,
+			      __u32 len)
+{
+	struct codec_list *entry;
+
+	entry = kzalloc(sizeof(*entry) + len, GFP_KERNEL);
+	if (!entry)
+		return -ENOMEM;
+
+	entry->id = sent->id;
+	if (sent->id == 0xFF) {
+		entry->cid = __le16_to_cpu(sent->cid);
+		entry->vid = __le16_to_cpu(sent->vid);
+	}
+	entry->transport = sent->transport;
+	entry->len = len;
+	entry->num_caps = rp->num_caps;
+	if (rp->num_caps)
+		memcpy(entry->caps, caps, len);
+	list_add(&entry->list, list);
+
+	return 0;
+}
+
+void hci_codec_list_clear(struct list_head *codec_list) {
+	struct codec_list *c, *n;
+
+	list_for_each_entry_safe(c, n, codec_list, list) {
+		list_del(&c->list);
+		kfree(c);
+	}
+}
+
+static void hci_read_codec_capabilities(struct hci_dev *hdev, void

*codec_id,

quoted

+					__u8 transport, bool is_vnd_codec) {
+	struct hci_op_read_local_codec_caps cmd;
+	__u8 i;
+
+	memset(&cmd, 0, sizeof(cmd));
+
+	if (is_vnd_codec) {
+		struct hci_vnd_codec *vnd_codec;
+
+		vnd_codec = codec_id;
+		cmd.id = 0xFF;
+		cmd.cid = vnd_codec->cid;
+		cmd.vid = vnd_codec->vid;
+	} else {
+		cmd.id = *(__u8 *)codec_id;
+	}
+
+	cmd.direction = 0x00;
+
+	for (i = 0; i < TRANSPORT_TYPE_MAX; i++) {
+		if (transport & BIT(i)) {
+			struct hci_rp_read_local_codec_caps *rp;
+			struct hci_codec_caps *caps;
+			struct sk_buff *skb;
+			__u8 j;
+			__u32 len;
+
+			cmd.transport = i;
+			skb = __hci_cmd_sync(hdev,

HCI_OP_READ_LOCAL_CODEC_CAPS,

quoted

+					     sizeof(cmd), &cmd,
+					     HCI_CMD_TIMEOUT);
+			if (IS_ERR(skb)) {
+				bt_dev_err(hdev, "Failed to read codec

capabilities (%ld)",

quoted

+					   PTR_ERR(skb));
+				continue;
+			}
+
+			if (skb->len < sizeof(*rp))
+				goto error;
+
+			rp = (void *)skb->data;
+
+			if (rp->status)
+				goto error;
+
+			if (!rp->num_caps) {
+				len = 0;
+				/* this codec doesn't have capabilities */
+				goto skip_caps_parse;
+			}
+
+			skb_pull(skb, sizeof(*rp));
+
+			for (j = 0, len = 0; j < rp->num_caps; j++) {
+				caps = (void *)skb->data;
+				if (skb->len < sizeof(*caps))
+					goto error;
+				if (skb->len < caps->len)
+					goto error;
+				len += sizeof(caps->len) + caps->len;
+				skb_pull(skb,  sizeof(caps->len) + caps->len);
+			}
+
+skip_caps_parse:
+			hci_dev_lock(hdev);
+			hci_codec_list_add(&hdev->local_codecs, &cmd, rp,
+					   (__u8 *)rp + sizeof(*rp), len);
+			hci_dev_unlock(hdev);
+error:
+			kfree_skb(skb);
+		}
+	}
+}
+
+static void hci_codec_list_parse(struct hci_dev *hdev, __u8 num_codecs,
+				 void *codec_list, bool is_vnd_codec) {
+	__u8 i;
+
+	for (i = 0; i < num_codecs; i++) {
+		if (!is_vnd_codec) {
+			struct hci_std_codecs *codecs = codec_list;
+
+			hci_read_codec_capabilities(hdev, &codecs-
codec[i],
+						    LOCAL_CODEC_ACL_MASK,
+						    is_vnd_codec);
+		} else {
+			struct hci_vnd_codecs *codecs = codec_list;
+
+			hci_read_codec_capabilities(hdev, &codecs-
codec[i],
+						    LOCAL_CODEC_ACL_MASK,
+						    is_vnd_codec);
+		}
+	}
+}

I said before that I don’t like it this way. The is_vnd_codec part is pointless
and you are trickling this through. I really mean that I am not wanting to it
this way upstream.

So first of all,

	if (is_vnd_codec) {
		int i;

		for (i = 0; i < num_codecs; i++) {
			struct hci_vnd_codecs *codecs = codec_list;
			hci_read_codec_capabilities(hdev, &codecs-

quoted

codec[i],

						    LOCAL_CODEC_ACL_MASK,
true);
		}
	} else {
		int I;

		for (i = 0; i < num_codecs; i++) {
			struct hci_std_codecs *codecs = codec_list;
			hci_read_codec_capabilities(hdev, &codecs-

quoted

codec[i],

						    LOCAL_CODEC_ACL_MASK,
false);
		}
	}

This is just by definition more efficient code. Now as caller you already know
if you are a vendor codec list or not.

	static void hci_codec_list_parse_std(struct hci_dev *hdev, __u8
num_codecs,
					     struct hci_std_codecs *codecs)
	{
		int i;

		for (i = 0; i < num_codecs; i++)
			hci_read_codec_capabilities(hdev, &codecs-

quoted

codec[i],

						    LOCAL_CODEC_ACL_MASK,
false);
	}

	static void hci_codec_list_parse_vnd(struct hci_dev *hdev, __u8
num_codecs,
					     struct hci_vnd_codecs *codecs)
	{
		..
	}


This is already less code and easier to understand. Also it is type safer since
the parameter is not a void pointer.

Ack.

Now on to the LOCAL_CODEC_ACL_MASK transport setting and the
hci_read_codec_capabilities. I have no idea why this is done this way. I can
not follow this code since it is spaghetti left and right. This needs to be
untangled.

HCI_READ_LOCAL_SUPPORTED_CODEC_CAPABILITIES command requires transport type to be specified.  In HCI_READ_LOCAL_SUPPORTED_CODECS_V1, by default transport type is BREDR_ACL. Hence in this patch, caller is explicitly passing LOCAL_CODEC_ACL_MASK.

In patch 02/10, transport bit mask received in HCI_READ_LOCAL_SUPPORTED_CODECS_V2, is passed.

I am not going to review hci_read_codec_capabilities right now, please look
through it and come up with simpler solution.

quoted

+
+void hci_read_supported_codecs(struct hci_dev *hdev) {
+	struct sk_buff *skb;
+	struct hci_rp_read_local_supported_codecs *rp;
+	struct hci_std_codecs *std_codecs;
+	struct hci_vnd_codecs *vnd_codecs;
+
+	skb = __hci_cmd_sync(hdev, HCI_OP_READ_LOCAL_CODECS, 0, NULL,
+			     HCI_CMD_TIMEOUT);
+
+	if (IS_ERR(skb)) {
+		bt_dev_err(hdev, "Failed to read local supported codecs

(%ld)",

quoted

+			   PTR_ERR(skb));
+		return;
+	}
+
+	if (skb->len < sizeof(*rp))
+		goto error;
+
+	rp = (void *)skb->data;
+
+	if (rp->status)
+		goto error;
+
+	skb_pull(skb, sizeof(rp->status));
+
+	std_codecs = (void *)skb->data;
+
+	/* validate codecs length before accessing */
+	if (skb->len < flex_array_size(std_codecs, codec, std_codecs->num)
+	    + sizeof(std_codecs->num))
+		goto error;
+
+	/* enumerate codec capabilities of standard codecs */
+	hci_codec_list_parse(hdev, std_codecs->num, std_codecs, false);

	for (i = 0; i < std_codecs->num; i++)
		hci_read_codec_capabilities(hdev, &std_codecs->codec[i],
					    LOCAL_CODEC_ACL_MASK, false);

Now I am saving the function above and only need 2 extra lines. This is more
readable since it is easier to follow.

quoted

+
+	skb_pull(skb, flex_array_size(std_codecs, codec, std_codecs->num)
+		 + sizeof(std_codecs->num));
+
+	vnd_codecs = (void *)skb->data;
+
+	/* validate vendor codecs length before accessing */
+	if (skb->len <
+	    flex_array_size(vnd_codecs, codec, vnd_codecs->num)
+	    + sizeof(vnd_codecs->num))
+		goto error;
+
+	/* enumerate vendor codec capabilities */
+	hci_codec_list_parse(hdev, vnd_codecs->num, vnd_codecs, true);
+
+error:
+	kfree_skb(skb);
+}

diff --git a/net/bluetooth/hci_codec.h b/net/bluetooth/hci_codec.h new

file mode 100644 index 000000000000..e5e594933d07

--- /dev/null
+++ b/net/bluetooth/hci_codec.h

@@ -0,0 +1,6 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+/* Copyright (C) 2021 Intel Corporation */
+
+void hci_read_supported_codecs(struct hci_dev *hdev); void
+hci_codec_list_clear(struct list_head *codec_list);

diff --git a/net/bluetooth/hci_core.c b/net/bluetooth/hci_core.c index

2560ed2f144d..212d5066d413 100644

--- a/net/bluetooth/hci_core.c
+++ b/net/bluetooth/hci_core.c

@@ -45,6 +45,7 @@

#include "leds.h"
#include "msft.h"
#include "aosp.h"
+#include "hci_codec.h"

static void hci_rx_work(struct work_struct *work); static void
hci_cmd_work(struct work_struct *work); @@ -838,10 +839,6 @@ static
int hci_init4_req(struct hci_request *req, unsigned long opt)
	if (hdev->commands[22] & 0x04)
		hci_set_event_mask_page_2(req);

-	/* Read local codec list if the HCI command is supported */
-	if (hdev->commands[29] & 0x20)
-		hci_req_add(req, HCI_OP_READ_LOCAL_CODECS, 0, NULL);
-
	/* Read local pairing options if the HCI command is supported */
	if (hdev->commands[41] & 0x08)
		hci_req_add(req, HCI_OP_READ_LOCAL_PAIRING_OPTS, 0,

NULL); @@ -937,6

quoted

+934,10 @@ static int __hci_init(struct hci_dev *hdev)
	if (err < 0)
		return err;

+	/* Read local codec list if the HCI command is supported */
+	if (hdev->commands[29] & 0x20)
+		hci_read_supported_codecs(hdev);
+
	/* This function is only called when the controller is actually in
	 * configured state. When the controller is marked as unconfigured,
	 * this initialization procedure is not run.

@@ -1841,6 +1842,7 @@ int hci_dev_do_close(struct hci_dev *hdev)

	memset(hdev->eir, 0, sizeof(hdev->eir));
	memset(hdev->dev_class, 0, sizeof(hdev->dev_class));
	bacpy(&hdev->random_addr, BDADDR_ANY);
+	hci_codec_list_clear(&hdev->local_codecs);

	hci_req_sync_unlock(hdev);

@@ -3842,7 +3844,7 @@ struct hci_dev *hci_alloc_dev(void)

	INIT_LIST_HEAD(&hdev->conn_hash.list);
	INIT_LIST_HEAD(&hdev->adv_instances);
	INIT_LIST_HEAD(&hdev->blocked_keys);
-
+	INIT_LIST_HEAD(&hdev->local_codecs);
	INIT_WORK(&hdev->rx_work, hci_rx_work);
	INIT_WORK(&hdev->cmd_work, hci_cmd_work);
	INIT_WORK(&hdev->tx_work, hci_tx_work);

This kind of style changes by removing an on purpose place empty line as
separator are not acceptable. Please avoid them.

Ack

Regards

Marcel

Regards,
Kiran