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

["K, Kiran" <kiran.k@intel.com>]

Hi Marcel,

> -----Original Message-----
> From: Marcel Holtmann <marcel@holtmann.org>
> Sent: Friday, July 30, 2021 7:36 PM
> To: K, Kiran <kiran.k@intel.com>
> Cc: BlueZ <linux-bluetooth@vger.kernel.org>; Srivatsa, Ravishankar
> <ravishankar.srivatsa@intel.com>; Tumkur Narayan, Chethan
> <chethan.tumkur.narayan@intel.com>
> Subject: Re: [PATCH v11 01/10] Bluetooth: Enumerate local supported codec
> and cache details
> 
> Hi Kiran,
> 
> > Move reading of supported local codecs into a separate init function,
> > query codecs capabilities and cache the data
> >
> > Signed-off-by: Kiran K <kiran.k@intel.com>
> > Signed-off-by: Chethan T N <chethan.tumkur.narayan@intel.com>
> > Signed-off-by: Srivatsa Ravishankar <ravishankar.srivatsa@intel.com>
> > ---
> > * 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,
> > #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,
> > +					__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,
> > +					     sizeof(cmd), &cmd,
> > +					     HCI_CMD_TIMEOUT);
> > +			if (IS_ERR(skb)) {
> > +				bt_dev_err(hdev, "Failed to read codec
> capabilities (%ld)",
> > +					   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-
> >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-
> >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-
> >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.
> 
> > +
> > +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)",
> > +			   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.
> 
> > +
> > +	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
> > +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