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Subject: Re: [PATCH v3 2/2] Bluetooth: Support the vendor specific debug
 events
From:   Marcel Holtmann <marcel@holtmann.org>
In-Reply-To: <20210413101812.323079-2-josephsih@chromium.org>
Date:   Tue, 13 Apr 2021 21:03:53 +0200
Cc:     "open list:BLUETOOTH DRIVERS" <linux-bluetooth@vger.kernel.org>,
        Luiz Augusto von Dentz <luiz.dentz@gmail.com>,
        =?utf-8?Q?Pali_Roh=C3=A1r?= <pali@kernel.org>,
        josephsih@google.com,
        CrosBT Upstreaming <chromeos-bluetooth-upstreaming@chromium.org>,
        Chethan T N <chethan.tumkur.narayan@intel.com>,
        Kiran Krishnappa <kiran.k@intel.com>,
        Miao-chen Chou <mcchou@chromium.org>,
        "David S. Miller" <davem@davemloft.net>,
        Jakub Kicinski <kuba@kernel.org>,
        Johan Hedberg <johan.hedberg@gmail.com>,
        open list <linux-kernel@vger.kernel.org>,
        netdev@vger.kernel.org
Content-Transfer-Encoding: 8BIT
Message-Id: <71CDAB34-92BD-48E9-8370-430AA1D967A4@holtmann.org>
References: <20210413101812.323079-1-josephsih@chromium.org>
 <20210413101812.323079-2-josephsih@chromium.org>
To:     Joseph Hwang <josephsih@chromium.org>
Precedence: bulk

Hi Joseph,

> This patch allows a user space process to enable/disable the vendor
> specific (vs) debug events dynamically through the set experimental
> feature mgmt interface if CONFIG_BT_FEATURE_VS_DBG_EVT is enabled.
> 
> Since the debug event feature needs to invoke the callback function
> provided by the driver, i.e., hdev->set_vs_dbg_evt, a valid controller
> index is required.
> 
> For generic Linux machines, the vendor specific debug events are
> disabled by default.
> 
> Reviewed-by: Chethan T N <chethan.tumkur.narayan@intel.com>
> Reviewed-by: Kiran Krishnappa <kiran.k@intel.com>
> Reviewed-by: Miao-chen Chou <mcchou@chromium.org>
> Signed-off-by: Joseph Hwang <josephsih@chromium.org>
> ---
> 
> (no changes since v1)
> 
> drivers/bluetooth/btintel.c      |  73 ++++++++++++++++++++-
> drivers/bluetooth/btintel.h      |  13 ++++
> drivers/bluetooth/btusb.c        |  16 +++++
> include/net/bluetooth/hci.h      |   4 ++
> include/net/bluetooth/hci_core.h |  10 +++
> net/bluetooth/Kconfig            |  10 +++
> net/bluetooth/mgmt.c             | 108 ++++++++++++++++++++++++++++++-
> 7 files changed, 232 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/bluetooth/btintel.c b/drivers/bluetooth/btintel.c
> index de1dbdc01e5a..c0f81d29aa5f 100644
> --- a/drivers/bluetooth/btintel.c
> +++ b/drivers/bluetooth/btintel.c
> @@ -1213,6 +1213,7 @@ void btintel_reset_to_bootloader(struct hci_dev *hdev)
> }
> EXPORT_SYMBOL_GPL(btintel_reset_to_bootloader);
> 
> +#ifdef CONFIG_BT_FEATURE_VS_DBG_EVT
> int btintel_read_debug_features(struct hci_dev *hdev,
> 				struct intel_debug_features *features)
> {
> @@ -1254,14 +1255,18 @@ int btintel_set_debug_features(struct hci_dev *hdev,
> 	u8 trace_enable = 0x02;
> 	struct sk_buff *skb;
> 
> -	if (!features)
> +	if (!features) {
> +		bt_dev_warn(hdev, "Debug features not read");
> 		return -EINVAL;
> +	}
> 
> 	if (!(features->page1[0] & 0x3f)) {
> 		bt_dev_info(hdev, "Telemetry exception format not supported");
> 		return 0;
> 	}
> 
> +	bt_dev_info(hdev, "trace_enable %d mask %d", trace_enable, mask[3]);
> +
> 	skb = __hci_cmd_sync(hdev, 0xfc8b, 11, mask, HCI_INIT_TIMEOUT);
> 	if (IS_ERR(skb)) {
> 		bt_dev_err(hdev, "Setting Intel telemetry ddc write event mask failed (%ld)",
> @@ -1290,6 +1295,72 @@ int btintel_set_debug_features(struct hci_dev *hdev,
> }
> EXPORT_SYMBOL_GPL(btintel_set_debug_features);
> 
> +int btintel_reset_debug_features(struct hci_dev *hdev,
> +				 const struct intel_debug_features *features)
> +{
> +	u8 mask[11] = { 0x0a, 0x92, 0x02, 0x00, 0x00, 0x00, 0x00, 0x00,
> +			0x00, 0x00, 0x00 };
> +	u8 trace_enable = 0x00;
> +	struct sk_buff *skb;
> +
> +	if (!features) {
> +		bt_dev_warn(hdev, "Debug features not read");
> +		return -EINVAL;
> +	}
> +
> +	if (!(features->page1[0] & 0x3f)) {
> +		bt_dev_info(hdev, "Telemetry exception format not supported");
> +		return 0;
> +	}
> +
> +	bt_dev_info(hdev, "trace_enable %d mask %d", trace_enable, mask[3]);
> +
> +	/* Should stop the trace before writing ddc event mask. */
> +	skb = __hci_cmd_sync(hdev, 0xfca1, 1, &trace_enable, HCI_INIT_TIMEOUT);
> +	if (IS_ERR(skb)) {
> +		bt_dev_err(hdev, "Stop tracing of link statistics events failed (%ld)",
> +			   PTR_ERR(skb));
> +		return PTR_ERR(skb);
> +	}
> +	kfree_skb(skb);
> +
> +	skb = __hci_cmd_sync(hdev, 0xfc8b, 11, mask, HCI_INIT_TIMEOUT);
> +	if (IS_ERR(skb)) {
> +		bt_dev_err(hdev, "Setting Intel telemetry ddc write event mask failed (%ld)",
> +			   PTR_ERR(skb));
> +		return PTR_ERR(skb);
> +	}
> +	kfree_skb(skb);
> +
> +	return 0;
> +}
> +EXPORT_SYMBOL_GPL(btintel_reset_debug_features);
> +
> +int btintel_set_vs_dbg_evt(struct hci_dev *hdev, bool enable)
> +{
> +	struct intel_debug_features features;
> +	int err;
> +
> +	bt_dev_dbg(hdev, "enable %d", enable);
> +
> +	/* Read the Intel supported features and if new exception formats
> +	 * supported, need to load the additional DDC config to enable.
> +	 */
> +	err = btintel_read_debug_features(hdev, &features);
> +	if (err)
> +		return err;
> +
> +	/* Set or reset the debug features. */
> +	if (enable)
> +		err = btintel_set_debug_features(hdev, &features);
> +	else
> +		err = btintel_reset_debug_features(hdev, &features);
> +
> +	return err;
> +}
> +EXPORT_SYMBOL_GPL(btintel_set_vs_dbg_evt);
> +#endif
> +
> MODULE_AUTHOR("Marcel Holtmann <marcel@holtmann.org>");
> MODULE_DESCRIPTION("Bluetooth support for Intel devices ver " VERSION);
> MODULE_VERSION(VERSION);
> diff --git a/drivers/bluetooth/btintel.h b/drivers/bluetooth/btintel.h
> index d184064a5e7c..0b35b0248b91 100644
> --- a/drivers/bluetooth/btintel.h
> +++ b/drivers/bluetooth/btintel.h
> @@ -171,10 +171,15 @@ int btintel_download_firmware_newgen(struct hci_dev *hdev,
> 				     u32 *boot_param, u8 hw_variant,
> 				     u8 sbe_type);
> void btintel_reset_to_bootloader(struct hci_dev *hdev);
> +#ifdef CONFIG_BT_FEATURE_VS_DBG_EVT
> int btintel_read_debug_features(struct hci_dev *hdev,
> 				struct intel_debug_features *features);
> int btintel_set_debug_features(struct hci_dev *hdev,
> 			       const struct intel_debug_features *features);
> +int btintel_reset_debug_features(struct hci_dev *hdev,
> +			       const struct intel_debug_features *features);
> +int btintel_set_vs_dbg_evt(struct hci_dev *hdev, bool enable);
> +#endif
> #else
> 
> static inline int btintel_check_bdaddr(struct hci_dev *hdev)
> @@ -301,10 +306,18 @@ static inline int btintel_read_debug_features(struct hci_dev *hdev,
> 	return -EOPNOTSUPP;
> }
> 
> +#ifdef CONFIG_BT_FEATURE_VS_DBG_EVT
> static inline int btintel_set_debug_features(struct hci_dev *hdev,
> 					     const struct intel_debug_features *features)
> {
> 	return -EOPNOTSUPP;
> }
> 
> +static inline int btintel_reset_debug_features(struct hci_dev *hdev,
> +					       const struct intel_debug_features *features)
> +{
> +	return -EOPNOTSUPP;
> +}
> +#endif
> +
> #endif
> diff --git a/drivers/bluetooth/btusb.c b/drivers/bluetooth/btusb.c
> index f29946f15f59..55e73d4f419f 100644
> --- a/drivers/bluetooth/btusb.c
> +++ b/drivers/bluetooth/btusb.c
> @@ -2864,6 +2864,11 @@ static int btusb_setup_intel_new(struct hci_dev *hdev)
> 		btintel_load_ddc_config(hdev, ddcname);
> 	}
> 
> +#ifdef CONFIG_BT_FEATURE_VS_DBG_EVT
> +	hci_dev_clear_flag(hdev, HCI_VS_DBG_EVT);
> +	bt_dev_dbg(hdev, "HCI_VS_DBG_EVT cleared");
> +#endif
> +
> 	/* Read the Intel version information after loading the FW  */
> 	err = btintel_read_version(hdev, &ver);
> 	if (err)
> @@ -2951,6 +2956,11 @@ static int btusb_setup_intel_newgen(struct hci_dev *hdev)
> 	 */
> 	btintel_load_ddc_config(hdev, ddcname);
> 
> +#ifdef CONFIG_BT_FEATURE_VS_DBG_EVT
> +	hci_dev_clear_flag(hdev, HCI_VS_DBG_EVT);
> +	bt_dev_dbg(hdev, "HCI_VS_DBG_EVT cleared");
> +#endif
> +
> 	/* Read the Intel version information after loading the FW  */
> 	err = btintel_read_version_tlv(hdev, &version);
> 	if (err)
> @@ -4587,6 +4597,9 @@ static int btusb_probe(struct usb_interface *intf,
> 		hdev->set_diag = btintel_set_diag;
> 		hdev->set_bdaddr = btintel_set_bdaddr;
> 		hdev->cmd_timeout = btusb_intel_cmd_timeout;
> +#ifdef CONFIG_BT_FEATURE_VS_DBG_EVT
> +		hdev->set_vs_dbg_evt = btintel_set_vs_dbg_evt;
> +#endif
> 		set_bit(HCI_QUIRK_STRICT_DUPLICATE_FILTER, &hdev->quirks);
> 		set_bit(HCI_QUIRK_SIMULTANEOUS_DISCOVERY, &hdev->quirks);
> 		set_bit(HCI_QUIRK_NON_PERSISTENT_DIAG, &hdev->quirks);
> @@ -4601,6 +4614,9 @@ static int btusb_probe(struct usb_interface *intf,
> 		hdev->set_diag = btintel_set_diag;
> 		hdev->set_bdaddr = btintel_set_bdaddr;
> 		hdev->cmd_timeout = btusb_intel_cmd_timeout;
> +#ifdef CONFIG_BT_FEATURE_VS_DBG_EVT
> +		hdev->set_vs_dbg_evt = btintel_set_vs_dbg_evt;
> +#endif
> 		set_bit(HCI_QUIRK_STRICT_DUPLICATE_FILTER, &hdev->quirks);
> 		set_bit(HCI_QUIRK_SIMULTANEOUS_DISCOVERY, &hdev->quirks);
> 		set_bit(HCI_QUIRK_NON_PERSISTENT_DIAG, &hdev->quirks);
> diff --git a/include/net/bluetooth/hci.h b/include/net/bluetooth/hci.h
> index ea4ae551c426..0c1eba73844a 100644
> --- a/include/net/bluetooth/hci.h
> +++ b/include/net/bluetooth/hci.h
> @@ -331,6 +331,10 @@ enum {
> 	HCI_CMD_PENDING,
> 	HCI_FORCE_NO_MITM,
> 
> +#ifdef CONFIG_BT_FEATURE_VS_DBG_EVT
> +	HCI_VS_DBG_EVT,
> +#endif
> +
> 	__HCI_NUM_FLAGS,
> };
> 
> diff --git a/include/net/bluetooth/hci_core.h b/include/net/bluetooth/hci_core.h
> index c73ac52af186..d68e06be51c7 100644
> --- a/include/net/bluetooth/hci_core.h
> +++ b/include/net/bluetooth/hci_core.h
> @@ -604,6 +604,9 @@ struct hci_dev {
> 	int (*set_bdaddr)(struct hci_dev *hdev, const bdaddr_t *bdaddr);
> 	void (*cmd_timeout)(struct hci_dev *hdev);
> 	bool (*prevent_wake)(struct hci_dev *hdev);
> +#ifdef CONFIG_BT_FEATURE_VS_DBG_EVT
> +	int (*set_vs_dbg_evt)(struct hci_dev *hdev, bool enable);
> +#endif

lets find a better name for this.

> };
> 
> #define HCI_PHY_HANDLE(handle)	(handle & 0xff)
> @@ -751,12 +754,19 @@ extern struct mutex hci_cb_list_lock;
> #define hci_dev_test_and_clear_flag(hdev, nr)  test_and_clear_bit((nr), (hdev)->dev_flags)
> #define hci_dev_test_and_change_flag(hdev, nr) test_and_change_bit((nr), (hdev)->dev_flags)
> 
> +#ifdef CONFIG_BT_FEATURE_VS_DBG_EVT
> +#define hci_dev_clear_flag_vs_dbg_evt(x) { hci_dev_clear_flag(hdev, x); }
> +#else
> +#define hci_dev_clear_flag_vs_dbg_evt(x) {}
> +#endif
> +
> #define hci_dev_clear_volatile_flags(hdev)			\
> 	do {							\
> 		hci_dev_clear_flag(hdev, HCI_LE_SCAN);		\
> 		hci_dev_clear_flag(hdev, HCI_LE_ADV);		\
> 		hci_dev_clear_flag(hdev, HCI_LL_RPA_RESOLUTION);\
> 		hci_dev_clear_flag(hdev, HCI_PERIODIC_INQ);	\
> +		hci_dev_clear_flag_vs_dbg_evt(HCI_VS_DBG_EVT)	\
> 	} while (0)
> 
> /* ----- HCI interface to upper protocols ----- */
> diff --git a/net/bluetooth/Kconfig b/net/bluetooth/Kconfig
> index e0ab4cd7afc3..4930ec495f60 100644
> --- a/net/bluetooth/Kconfig
> +++ b/net/bluetooth/Kconfig
> @@ -148,4 +148,14 @@ config BT_FEATURE_DEBUG
> 	  This provides an option to enable/disable debugging statements
> 	  at runtime via the experimental features interface.
> 
> +config BT_FEATURE_VS_DBG_EVT
> +	bool "Enable runtime option for logging vendor specific debug events"
> +	depends on BT && !DYNAMIC_DEBUG
> +	default n
> +	help
> +	  This provides an option to enable/disable vendor specific debug
> +	  events logging at runtime via the experimental features interface.
> +	  The debug events may include the categories of system exceptions,
> +	  connections/disconnection, the link quality statistics, etc.
> +

So I am not convinced this needs to be compile time option. I also don’t understand the !DYNAMIC_DEBUG portion.

> source "drivers/bluetooth/Kconfig"
> diff --git a/net/bluetooth/mgmt.c b/net/bluetooth/mgmt.c
> index f9be7f9084d6..a4344b78a6a0 100644
> --- a/net/bluetooth/mgmt.c
> +++ b/net/bluetooth/mgmt.c
> @@ -3788,6 +3788,14 @@ static const u8 debug_uuid[16] = {
> };
> #endif
> 
> +#ifdef CONFIG_BT_FEATURE_VS_DBG_EVT
> +/* 330859bc-7506-492d-9370-9a6f0614037f */
> +static const u8 vs_dbg_evt_uuid[16] = {
> +	0x7f, 0x03, 0x14, 0x06, 0x6f, 0x9a, 0x70, 0x93,
> +	0x2d, 0x49, 0x06, 0x75, 0xbc, 0x59, 0x08, 0x33,
> +};
> +#endif
> +
> /* 671b10b5-42c0-4696-9227-eb28d1b049d6 */
> static const u8 simult_central_periph_uuid[16] = {
> 	0xd6, 0x49, 0xb0, 0xd1, 0x28, 0xeb, 0x27, 0x92,
> @@ -3803,7 +3811,7 @@ static const u8 rpa_resolution_uuid[16] = {
> static int read_exp_features_info(struct sock *sk, struct hci_dev *hdev,
> 				  void *data, u16 data_len)
> {
> -	char buf[62];	/* Enough space for 3 features */
> +	char buf[82];   /* Enough space for 4 features: 2 + 20 * 4 */
> 	struct mgmt_rp_read_exp_features_info *rp = (void *)buf;
> 	u16 idx = 0;
> 	u32 flags;
> @@ -3847,6 +3855,15 @@ static int read_exp_features_info(struct sock *sk, struct hci_dev *hdev,
> 		idx++;
> 	}
> 
> +#ifdef CONFIG_BT_FEATURE_VS_DBG_EVT
> +	if (hdev) {
> +		flags = hci_dev_test_flag(hdev, HCI_VS_DBG_EVT) ? BIT(0) : 0;
> +		memcpy(rp->features[idx].uuid, vs_dbg_evt_uuid, 16);
> +		rp->features[idx].flags = cpu_to_le32(flags);
> +		idx++;
> +	}
> +#endif
> +
> 	rp->feature_count = cpu_to_le16(idx);
> 
> 	/* After reading the experimental features information, enable
> @@ -3889,6 +3906,23 @@ static int exp_debug_feature_changed(bool enabled, struct sock *skip)
> }
> #endif
> 
> +#ifdef CONFIG_BT_FEATURE_VS_DBG_EVT
> +static int exp_vs_dbg_evt_feature_changed(bool enabled, struct sock *skip)
> +{
> +	struct mgmt_ev_exp_feature_changed ev;
> +
> +	BT_INFO("enabled %d", enabled);
> +
> +	memset(&ev, 0, sizeof(ev));
> +	memcpy(ev.uuid, vs_dbg_evt_uuid, 16);
> +	ev.flags = cpu_to_le32(enabled ? BIT(0) : 0);
> +
> +	return mgmt_limited_event(MGMT_EV_EXP_FEATURE_CHANGED, NULL,
> +				  &ev, sizeof(ev),
> +				  HCI_MGMT_EXP_FEATURE_EVENTS, skip);
> +}
> +#endif
> +
> static int set_exp_feature(struct sock *sk, struct hci_dev *hdev,
> 			   void *data, u16 data_len)
> {
> @@ -4035,6 +4069,78 @@ static int set_exp_feature(struct sock *sk, struct hci_dev *hdev,
> 		return err;
> 	}
> 
> +#ifdef CONFIG_BT_FEATURE_VS_DBG_EVT
> +	if (!memcmp(cp->uuid, vs_dbg_evt_uuid, 16)) {
> +		bool val, changed;
> +		int err;
> +		u16 mgmt_index = hdev ? hdev->id : MGMT_INDEX_NONE;

Since this is controller specific, this needs to be a valid hdev in the first place.

> +
> +		/* Command requires to use a valid controller index */
> +		if (!hdev)
> +			return mgmt_cmd_status(sk, hdev->id,
> +					       MGMT_OP_SET_EXP_FEATURE,
> +					       MGMT_STATUS_INVALID_INDEX);
> +
> +		/* Parameters are limited to a single octet */
> +		if (data_len != MGMT_SET_EXP_FEATURE_SIZE + 1)
> +			return mgmt_cmd_status(sk, mgmt_index,
> +					       MGMT_OP_SET_EXP_FEATURE,
> +					       MGMT_STATUS_INVALID_PARAMS);
> +
> +		/* Only boolean on/off is supported */
> +		if (cp->param[0] != 0x00 && cp->param[0] != 0x01)
> +			return mgmt_cmd_status(sk, mgmt_index,
> +					       MGMT_OP_SET_EXP_FEATURE,
> +					       MGMT_STATUS_INVALID_PARAMS);
> +
> +		hci_req_sync_lock(hdev);
> +
> +		val = !!cp->param[0];
> +		changed = (val != hci_dev_test_flag(hdev, HCI_VS_DBG_EVT));
> +
> +		if (!hdev->set_vs_dbg_evt) {
> +			BT_INFO("vendor specific debug event not supported");

No, this is not how we do things. If there is no support for debug events, then we don’t advertise this experimental feature.

> +			err = mgmt_cmd_status(sk, mgmt_index,
> +					      MGMT_OP_SET_EXP_FEATURE,
> +					      MGMT_STATUS_NOT_SUPPORTED);
> +			goto unlock_vs_dbg_evt;
> +		}
> +
> +		if (changed) {
> +			err = hdev->set_vs_dbg_evt(hdev, val);

So is this something that requires a powered controller or is it fine to just do it on a powered down controller?

> +			if (err) {
> +				BT_ERR("set_vs_dbg_evt value %d err %d",
> +				       val, err);
> +				err = mgmt_cmd_status(sk, mgmt_index,
> +						      MGMT_OP_SET_EXP_FEATURE,
> +						      MGMT_STATUS_FAILED);
> +				goto unlock_vs_dbg_evt;
> +			}
> +			if (val)
> +				hci_dev_set_flag(hdev, HCI_VS_DBG_EVT);
> +			else
> +				hci_dev_clear_flag(hdev, HCI_VS_DBG_EVT);
> +		}
> +
> +		BT_INFO("vendor specific debug event %d changed %d",
> +			val, changed);
> +
> +		memcpy(rp.uuid, vs_dbg_evt_uuid, 16);
> +		rp.flags = cpu_to_le32(val ? BIT(0) : 0);
> +		hci_sock_set_flag(sk, HCI_MGMT_EXP_FEATURE_EVENTS);
> +		err = mgmt_cmd_complete(sk, mgmt_index,
> +					MGMT_OP_SET_EXP_FEATURE, 0,
> +					&rp, sizeof(rp));
> +
> +		if (changed)
> +			exp_vs_dbg_evt_feature_changed(val, sk);
> +
> +unlock_vs_dbg_evt:
> +		hci_req_sync_unlock(hdev);
> +		return err;
> +	}
> +#endif
> +
> 	return mgmt_cmd_status(sk, hdev ? hdev->id : MGMT_INDEX_NONE,
> 			       MGMT_OP_SET_EXP_FEATURE,
> 			       MGMT_STATUS_NOT_SUPPORTED);

Regards

Marcel