[PATCH v4] Bluetooth: l2cap: defer conn param update to avoid conn->lock/hdev->lock inversion

[PATCH v4] Bluetooth: l2cap: defer conn param update to avoid conn->lock/hdev->lock inversion

[Mikhail Gavrilov]

When a BLE peripheral sends an L2CAP Connection Parameter Update Request
the processing path is:

  process_pending_rx()          [takes conn->lock]
    l2cap_le_sig_channel()
      l2cap_conn_param_update_req()
        hci_le_conn_update()    [takes hdev->lock]

Meanwhile other code paths take the locks in the opposite order:

  l2cap_chan_connect()          [takes hdev->lock]
    ...
      mutex_lock(&conn->lock)

  l2cap_conn_ready()            [hdev->lock via hci_cb_list_lock]
    ...
      mutex_lock(&conn->lock)

This is a classic AB/BA deadlock which lockdep reports as a circular
locking dependency when connecting a BLE MIDI keyboard (Carry-On FC-49).

Fix this by making hci_le_conn_update() defer the HCI command through
hci_cmd_sync_queue() so it no longer needs to take hdev->lock in the
caller context.  The sync callback uses __hci_cmd_sync_status_sk() to
wait for the HCI_EV_LE_CONN_UPDATE_COMPLETE event, then updates the
stored connection parameters (hci_conn_params) and notifies userspace
(mgmt_new_conn_param) only after the controller has confirmed the update.

A reference on hci_conn is held via hci_conn_get()/hci_conn_put() for
the lifetime of the queued work to prevent use-after-free, and
hci_conn_valid() is checked before proceeding in case the connection was
removed while the work was pending.

Fixes: f044eb0524a0 ("Bluetooth: Store latency and supervision timeout in connection params")
Signed-off-by: Mikhail Gavrilov <mikhail.v.gavrilov@gmail.com>
Reviewed-by: Paul Menzel <pmenzel@molgen.mpg.de>
---

Changes in v4 (Luiz Augusto von Dentz, Sashiko/Gemini AI review):
- Use hci_conn_get()/hci_conn_put() to hold a reference while work is queued
- Use __hci_cmd_sync_status_sk() to wait for HCI_EV_LE_CONN_UPDATE_COMPLETE,
  then do params update + mgmt notification in the sync callback — removes the
  need for hci_event.c changes and hci_sent_cmd_data()
- Use kzalloc_obj() per checkpatch recommendation
- Fix checkpatch alignment issues
 
Changes in v3 (Luiz Augusto von Dentz):
- Move hci_cmd_sync_queue into hci_le_conn_update itself instead of open-coding
  the deferral in l2cap_core.c
- Move conn_params update and mgmt_new_conn_param into
  hci_le_conn_update_complete_evt, using hci_sent_cmd_data to retrieve
  the originally requested parameters
 
Changes in v2 (Paul Menzel, Sashiko/Gemini AI review):
- Allocate before sending ACCEPTED response to avoid state mismatch on OOM
- Verify connection handle and address in sync callback against reuse race
- Expand commit message with implementation details

 include/net/bluetooth/hci_core.h |  2 +-
 net/bluetooth/hci_conn.c         | 98 +++++++++++++++++++++++++-------
 net/bluetooth/l2cap_core.c       | 12 +---
 3 files changed, 82 insertions(+), 30 deletions(-)

diff --git a/include/net/bluetooth/hci_core.h b/include/net/bluetooth/hci_core.h
index a7bffb908c1e..aa600fbf9a53 100644
--- a/include/net/bluetooth/hci_core.h
+++ b/include/net/bluetooth/hci_core.h
@@ -2495,7 +2495,7 @@ void mgmt_adv_monitor_device_lost(struct hci_dev *hdev, u16 handle,
 				  bdaddr_t *bdaddr, u8 addr_type);
 
 int hci_abort_conn(struct hci_conn *conn, u8 reason);
-u8 hci_le_conn_update(struct hci_conn *conn, u16 min, u16 max, u16 latency,
+void hci_le_conn_update(struct hci_conn *conn, u16 min, u16 max, u16 latency,
 		      u16 to_multiplier);
 void hci_le_start_enc(struct hci_conn *conn, __le16 ediv, __le64 rand,
 		      __u8 ltk[16], __u8 key_size);
diff --git a/net/bluetooth/hci_conn.c b/net/bluetooth/hci_conn.c
index 11d3ad8d2551..c9cc18fab1f2 100644
--- a/net/bluetooth/hci_conn.c
+++ b/net/bluetooth/hci_conn.c
@@ -480,40 +480,100 @@ bool hci_setup_sync(struct hci_conn *conn, __u16 handle)
 	return hci_setup_sync_conn(conn, handle);
 }
 
-u8 hci_le_conn_update(struct hci_conn *conn, u16 min, u16 max, u16 latency,
-		      u16 to_multiplier)
+struct le_conn_update_data {
+	struct hci_conn *conn;
+	u16	min;
+	u16	max;
+	u16	latency;
+	u16	to_multiplier;
+};
+
+static int le_conn_update_sync(struct hci_dev *hdev, void *data)
 {
-	struct hci_dev *hdev = conn->hdev;
+	struct le_conn_update_data *d = data;
+	struct hci_conn *conn = d->conn;
 	struct hci_conn_params *params;
 	struct hci_cp_le_conn_update cp;
+	u8 store_hint;
+	int err;
 
+	/* Verify connection is still alive. */
 	hci_dev_lock(hdev);
-
-	params = hci_conn_params_lookup(hdev, &conn->dst, conn->dst_type);
-	if (params) {
-		params->conn_min_interval = min;
-		params->conn_max_interval = max;
-		params->conn_latency = latency;
-		params->supervision_timeout = to_multiplier;
+	if (!hci_conn_valid(hdev, conn)) {
+		hci_dev_unlock(hdev);
+		return -ECANCELED;
 	}
-
 	hci_dev_unlock(hdev);
 
 	memset(&cp, 0, sizeof(cp));
 	cp.handle		= cpu_to_le16(conn->handle);
-	cp.conn_interval_min	= cpu_to_le16(min);
-	cp.conn_interval_max	= cpu_to_le16(max);
-	cp.conn_latency		= cpu_to_le16(latency);
-	cp.supervision_timeout	= cpu_to_le16(to_multiplier);
+	cp.conn_interval_min	= cpu_to_le16(d->min);
+	cp.conn_interval_max	= cpu_to_le16(d->max);
+	cp.conn_latency		= cpu_to_le16(d->latency);
+	cp.supervision_timeout	= cpu_to_le16(d->to_multiplier);
 	cp.min_ce_len		= cpu_to_le16(0x0000);
 	cp.max_ce_len		= cpu_to_le16(0x0000);
 
-	hci_send_cmd(hdev, HCI_OP_LE_CONN_UPDATE, sizeof(cp), &cp);
+	err = __hci_cmd_sync_status_sk(hdev, HCI_OP_LE_CONN_UPDATE,
+				       sizeof(cp), &cp,
+				       HCI_EV_LE_CONN_UPDATE_COMPLETE,
+				       HCI_CMD_TIMEOUT, NULL);
+	if (err)
+		return err;
+
+	/* Update stored connection parameters after the controller has
+	 * confirmed the update via the LE Connection Update Complete event.
+	 */
+	hci_dev_lock(hdev);
 
-	if (params)
-		return 0x01;
+	params = hci_conn_params_lookup(hdev, &conn->dst, conn->dst_type);
+	if (params) {
+		params->conn_min_interval = d->min;
+		params->conn_max_interval = d->max;
+		params->conn_latency = d->latency;
+		params->supervision_timeout = d->to_multiplier;
+		store_hint = 0x01;
+	} else {
+		store_hint = 0x00;
+	}
 
-	return 0x00;
+	hci_dev_unlock(hdev);
+
+	mgmt_new_conn_param(hdev, &conn->dst, conn->dst_type, store_hint,
+			    d->min, d->max, d->latency, d->to_multiplier);
+
+	return 0;
+}
+
+static void le_conn_update_complete(struct hci_dev *hdev, void *data, int err)
+{
+	struct le_conn_update_data *d = data;
+
+	hci_conn_put(d->conn);
+	kfree(d);
+}
+
+void hci_le_conn_update(struct hci_conn *conn, u16 min, u16 max, u16 latency,
+			u16 to_multiplier)
+{
+	struct le_conn_update_data *d;
+
+	d = kzalloc_obj(*d);
+	if (!d)
+		return;
+
+	hci_conn_get(conn);
+	d->conn = conn;
+	d->min = min;
+	d->max = max;
+	d->latency = latency;
+	d->to_multiplier = to_multiplier;
+
+	if (hci_cmd_sync_queue(conn->hdev, le_conn_update_sync, d,
+			       le_conn_update_complete) < 0) {
+		hci_conn_put(conn);
+		kfree(d);
+	}
 }
 
 void hci_le_start_enc(struct hci_conn *conn, __le16 ediv, __le64 rand,
diff --git a/net/bluetooth/l2cap_core.c b/net/bluetooth/l2cap_core.c
index 95c65fece39b..aac2db1d6fbb 100644
--- a/net/bluetooth/l2cap_core.c
+++ b/net/bluetooth/l2cap_core.c
@@ -4706,16 +4706,8 @@ static inline int l2cap_conn_param_update_req(struct l2cap_conn *conn,
 	l2cap_send_cmd(conn, cmd->ident, L2CAP_CONN_PARAM_UPDATE_RSP,
 		       sizeof(rsp), &rsp);
 
-	if (!err) {
-		u8 store_hint;
-
-		store_hint = hci_le_conn_update(hcon, min, max, latency,
-						to_multiplier);
-		mgmt_new_conn_param(hcon->hdev, &hcon->dst, hcon->dst_type,
-				    store_hint, min, max, latency,
-				    to_multiplier);
-
-	}
+	if (!err)
+		hci_le_conn_update(hcon, min, max, latency, to_multiplier);
 
 	return 0;
 }
-- 
2.53.0

RE: [v4] Bluetooth: l2cap: defer conn param update to avoid conn->lock/hdev->lock inversion

[bluez.test.bot]

[-- Attachment #1: Type: text/plain, Size: 7456 bytes --]

This is automated email and please do not reply to this email!

Dear submitter,

Thank you for submitting the patches to the linux bluetooth mailing list.
This is a CI test results with your patch series:
PW Link:https://patchwork.kernel.org/project/bluetooth/list/?series=1081253

---Test result---

Test Summary:
CheckPatch                    PASS      1.14 seconds
GitLint                       FAIL      0.29 seconds
SubjectPrefix                 PASS      0.10 seconds
BuildKernel                   PASS      26.88 seconds
CheckAllWarning               PASS      29.13 seconds
CheckSparse                   PASS      27.61 seconds
BuildKernel32                 PASS      25.61 seconds
TestRunnerSetup               PASS      579.82 seconds
TestRunner_l2cap-tester       PASS      29.45 seconds
TestRunner_iso-tester         PASS      44.08 seconds
TestRunner_bnep-tester        PASS      6.56 seconds
TestRunner_mgmt-tester        FAIL      120.96 seconds
TestRunner_rfcomm-tester      PASS      9.68 seconds
TestRunner_sco-tester         FAIL      14.47 seconds
TestRunner_ioctl-tester       PASS      10.66 seconds
TestRunner_mesh-tester        FAIL      12.21 seconds
TestRunner_smp-tester         PASS      8.79 seconds
TestRunner_userchan-tester    PASS      6.89 seconds
TestRunner_6lowpan-tester     FAIL      8.80 seconds
IncrementalBuild              FAIL      0.00 seconds

Details
##############################
Test: GitLint - FAIL
Desc: Run gitlint
Output:
[v4] Bluetooth: l2cap: defer conn param update to avoid conn->lock/hdev->lock inversion

WARNING: I3 - ignore-body-lines: gitlint will be switching from using Python regex 'match' (match beginning) to 'search' (match anywhere) semantics. Please review your ignore-body-lines.regex option accordingly. To remove this warning, set general.regex-style-search=True. More details: https://jorisroovers.github.io/gitlint/configuration/#regex-style-search
1: T1 Title exceeds max length (87>80): "[v4] Bluetooth: l2cap: defer conn param update to avoid conn->lock/hdev->lock inversion"
47: B2 Line has trailing whitespace: " "
54: B2 Line has trailing whitespace: " "
##############################
Test: TestRunner_mgmt-tester - FAIL
Desc: Run mgmt-tester with test-runner
Output:
Total: 494, Passed: 489 (99.0%), Failed: 1, Not Run: 4

Failed Test Cases
Read Exp Feature - Success                           Failed       0.120 seconds
##############################
Test: TestRunner_sco-tester - FAIL
Desc: Run sco-tester with test-runner
Output:
WARNING: possible circular locking dependency detected
7.0.0-rc2-g40cbfa4250a5 #1 Not tainted
------------------------------------------------------
kworker/u5:2/117 is trying to acquire lock:
ffff888001abd240 (sk_lock-AF_BLUETOOTH-BTPROTO_SCO){+.+.}-{0:0}, at: sco_connect_cfm+0x358/0x8d0

but task is already holding lock:
ffff8880025f7220 (&conn->lock){+.+.}-{3:3}, at: sco_connect_cfm+0x22d/0x8d0

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #1 (&conn->lock){+.+.}-{3:3}:
       lock_acquire+0xf7/0x2c0
       _raw_spin_lock+0x2a/0x40
       sco_sock_connect+0x4d7/0x1280
       __sys_connect+0x1a3/0x260
       __x64_sys_connect+0x6e/0xb0
       do_syscall_64+0xa0/0x570
       entry_SYSCALL_64_after_hwframe+0x74/0x7c

-> #0 (sk_lock-AF_BLUETOOTH-BTPROTO_SCO){+.+.}-{0:0}:
       check_prev_add+0xe9/0xc70
       __lock_acquire+0x1457/0x1df0
       lock_acquire+0xf7/0x2c0
       lock_sock_nested+0x36/0xd0
       sco_connect_cfm+0x358/0x8d0
       hci_sync_conn_complete_evt+0x3d3/0x8e0
       hci_event_packet+0x74f/0xb10
       hci_rx_work+0x398/0xd00
       process_scheduled_works+0xb16/0x1ac0
       worker_thread+0x4ff/0xba0
       kthread+0x368/0x490
       ret_from_fork+0x498/0x7e0
       ret_from_fork_asm+0x19/0x30

other info that might help us debug this:

...
BUG: sleeping function called from invalid context at net/core/sock.c:3782
in_atomic(): 1, irqs_disabled(): 0, non_block: 0, pid: 117, name: kworker/u5:2
preempt_count: 1, expected: 0
RCU nest depth: 0, expected: 0
INFO: lockdep is turned off.
CPU: 0 UID: 0 PID: 117 Comm: kworker/u5:2 Not tainted 7.0.0-rc2-g40cbfa4250a5 #1 PREEMPT(lazy) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.13.0-1ubuntu1.1 04/01/2014
Workqueue: hci0 hci_rx_work
Call Trace:
 <TASK>
 dump_stack_lvl+0x49/0x60
 __might_resched+0x2ea/0x500
 lock_sock_nested+0x47/0xd0
 ? sco_connect_cfm+0x358/0x8d0
 sco_connect_cfm+0x358/0x8d0
 ? hci_debugfs_create_conn+0x190/0x210
 ? __pfx_sco_connect_cfm+0x10/0x10
 hci_sync_conn_complete_evt+0x3d3/0x8e0
 hci_event_packet+0x74f/0xb10
 ? __pfx_hci_sync_conn_complete_evt+0x10/0x10
 ? __pfx_hci_event_packet+0x10/0x10
 ? mark_held_locks+0x49/0x80
 ? lockdep_hardirqs_on_prepare+0xd4/0x180
 ? _raw_spin_unlock_irqrestore+0x2c/0x50
 hci_rx_work+0x398/0xd00
 process_scheduled_works+0xb16/0x1ac0
 ? __pfx_process_scheduled_works+0x10/0x10
 ? lock_acquire+0xf7/0x2c0
 ? lock_is_held_type+0x9b/0x110
 ? __pfx_hci_rx_work+0x10/0x10
 worker_thread+0x4ff/0xba0
 ? _raw_spin_unlock_irqrestore+0x2c/0x50
 ? __pfx_worker_thread+0x10/0x10
 kthread+0x368/0x490
 ? _raw_spin_unlock_irq+0x23/0x40
 ? __pfx_kthread+0x10/0x10
 ret_from_fork+0x498/0x7e0
 ? __pfx_ret_from_fork+0x10/0x10
 ? __switch_to+0x9e4/0xe50
 ? __switch_to_asm+0x32/0x60
...
Total: 30, Passed: 30 (100.0%), Failed: 0, Not Run: 0
##############################
Test: TestRunner_mesh-tester - FAIL
Desc: Run mesh-tester with test-runner
Output:
Total: 10, Passed: 8 (80.0%), Failed: 2, Not Run: 0

Failed Test Cases
Mesh - Send cancel - 1                               Timed out    2.631 seconds
Mesh - Send cancel - 2                               Timed out    1.993 seconds
##############################
Test: TestRunner_6lowpan-tester - FAIL
Desc: Run 6lowpan-tester with test-runner
Output:
WARNING: possible circular locking dependency detected
7.0.0-rc2-g40cbfa4250a5 #1 Not tainted
------------------------------------------------------
kworker/0:1/11 is trying to acquire lock:
ffff88800275c940 ((wq_completion)hci0#2){+.+.}-{0:0}, at: touch_wq_lockdep_map+0x75/0x180

but task is already holding lock:
ffffffffaac4d720 (rtnl_mutex){+.+.}-{4:4}, at: lowpan_unregister_netdev+0xd/0x30

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #4 (rtnl_mutex){+.+.}-{4:4}:
       lock_acquire+0xf7/0x2c0
       __mutex_lock+0x16b/0x1fc0
       lowpan_register_netdev+0x11/0x30
       chan_ready_cb+0x836/0xd00
       l2cap_recv_frame+0x6a07/0x88a0
       l2cap_recv_acldata+0x790/0xdf0
       hci_rx_work+0x500/0xd00
       process_scheduled_works+0xb16/0x1ac0
       worker_thread+0x4ff/0xba0
       kthread+0x368/0x490
       ret_from_fork+0x498/0x7e0
       ret_from_fork_asm+0x19/0x30

-> #3 (&chan->lock#3/1){+.+.}-{4:4}:
       lock_acquire+0xf7/0x2c0
       __mutex_lock+0x16b/0x1fc0
       l2cap_chan_connect+0x74e/0x1980
       lowpan_control_write+0x523/0x660
       full_proxy_write+0x10b/0x190
       vfs_write+0x1c0/0xf60
       ksys_write+0xf1/0x1d0
       do_syscall_64+0xa0/0x570
       entry_SYSCALL_64_after_hwframe+0x74/0x7c

-> #2 (&conn->lock){+.+.}-{4:4}:
...
Total: 8, Passed: 8 (100.0%), Failed: 0, Not Run: 0
##############################
Test: IncrementalBuild - FAIL
Desc: Incremental build with the patches in the series
Output:
Failed to reset to base commit


https://github.com/bluez/bluetooth-next/pull/83

---
Regards,
Linux Bluetooth

Re: [PATCH v4] Bluetooth: l2cap: defer conn param update to avoid conn->lock/hdev->lock inversion

[Pauli Virtanen]

ti, 2026-04-14 kello 23:43 +0500, Mikhail Gavrilov kirjoitti:
> When a BLE peripheral sends an L2CAP Connection Parameter Update Request
> the processing path is:
> 
>   process_pending_rx()          [takes conn->lock]
>     l2cap_le_sig_channel()
>       l2cap_conn_param_update_req()
>         hci_le_conn_update()    [takes hdev->lock]
> 
> Meanwhile other code paths take the locks in the opposite order:
> 
>   l2cap_chan_connect()          [takes hdev->lock]
>     ...
>       mutex_lock(&conn->lock)
> 
>   l2cap_conn_ready()            [hdev->lock via hci_cb_list_lock]
>     ...
>       mutex_lock(&conn->lock)
> 
> This is a classic AB/BA deadlock which lockdep reports as a circular
> locking dependency when connecting a BLE MIDI keyboard (Carry-On FC-49).
> 
> Fix this by making hci_le_conn_update() defer the HCI command through
> hci_cmd_sync_queue() so it no longer needs to take hdev->lock in the
> caller context.  The sync callback uses __hci_cmd_sync_status_sk() to
> wait for the HCI_EV_LE_CONN_UPDATE_COMPLETE event, then updates the
> stored connection parameters (hci_conn_params) and notifies userspace
> (mgmt_new_conn_param) only after the controller has confirmed the update.
> 
> A reference on hci_conn is held via hci_conn_get()/hci_conn_put() for
> the lifetime of the queued work to prevent use-after-free, and
> hci_conn_valid() is checked before proceeding in case the connection was
> removed while the work was pending.
> 
> Fixes: f044eb0524a0 ("Bluetooth: Store latency and supervision timeout in connection params")
> Signed-off-by: Mikhail Gavrilov <mikhail.v.gavrilov@gmail.com>
> Reviewed-by: Paul Menzel <pmenzel@molgen.mpg.de>
> ---
> 
> Changes in v4 (Luiz Augusto von Dentz, Sashiko/Gemini AI review):
> - Use hci_conn_get()/hci_conn_put() to hold a reference while work is queued
> - Use __hci_cmd_sync_status_sk() to wait for HCI_EV_LE_CONN_UPDATE_COMPLETE,
>   then do params update + mgmt notification in the sync callback — removes the
>   need for hci_event.c changes and hci_sent_cmd_data()
> - Use kzalloc_obj() per checkpatch recommendation
> - Fix checkpatch alignment issues
>  
> Changes in v3 (Luiz Augusto von Dentz):
> - Move hci_cmd_sync_queue into hci_le_conn_update itself instead of open-coding
>   the deferral in l2cap_core.c
> - Move conn_params update and mgmt_new_conn_param into
>   hci_le_conn_update_complete_evt, using hci_sent_cmd_data to retrieve
>   the originally requested parameters
>  
> Changes in v2 (Paul Menzel, Sashiko/Gemini AI review):
> - Allocate before sending ACCEPTED response to avoid state mismatch on OOM
> - Verify connection handle and address in sync callback against reuse race
> - Expand commit message with implementation details
> 
>  include/net/bluetooth/hci_core.h |  2 +-
>  net/bluetooth/hci_conn.c         | 98 +++++++++++++++++++++++++-------
>  net/bluetooth/l2cap_core.c       | 12 +---
>  3 files changed, 82 insertions(+), 30 deletions(-)
> 
> diff --git a/include/net/bluetooth/hci_core.h b/include/net/bluetooth/hci_core.h
> index a7bffb908c1e..aa600fbf9a53 100644
> --- a/include/net/bluetooth/hci_core.h
> +++ b/include/net/bluetooth/hci_core.h
> @@ -2495,7 +2495,7 @@ void mgmt_adv_monitor_device_lost(struct hci_dev *hdev, u16 handle,
>  				  bdaddr_t *bdaddr, u8 addr_type);
>  
>  int hci_abort_conn(struct hci_conn *conn, u8 reason);
> -u8 hci_le_conn_update(struct hci_conn *conn, u16 min, u16 max, u16 latency,
> +void hci_le_conn_update(struct hci_conn *conn, u16 min, u16 max, u16 latency,
>  		      u16 to_multiplier);
>  void hci_le_start_enc(struct hci_conn *conn, __le16 ediv, __le64 rand,
>  		      __u8 ltk[16], __u8 key_size);
> diff --git a/net/bluetooth/hci_conn.c b/net/bluetooth/hci_conn.c
> index 11d3ad8d2551..c9cc18fab1f2 100644
> --- a/net/bluetooth/hci_conn.c
> +++ b/net/bluetooth/hci_conn.c
> @@ -480,40 +480,100 @@ bool hci_setup_sync(struct hci_conn *conn, __u16 handle)
>  	return hci_setup_sync_conn(conn, handle);
>  }
>  
> -u8 hci_le_conn_update(struct hci_conn *conn, u16 min, u16 max, u16 latency,
> -		      u16 to_multiplier)
> +struct le_conn_update_data {
> +	struct hci_conn *conn;
> +	u16	min;
> +	u16	max;
> +	u16	latency;
> +	u16	to_multiplier;
> +};
> +
> +static int le_conn_update_sync(struct hci_dev *hdev, void *data)
>  {
> -	struct hci_dev *hdev = conn->hdev;
> +	struct le_conn_update_data *d = data;
> +	struct hci_conn *conn = d->conn;
>  	struct hci_conn_params *params;
>  	struct hci_cp_le_conn_update cp;
> +	u8 store_hint;
> +	int err;
>  
> +	/* Verify connection is still alive. */
>  	hci_dev_lock(hdev);
> -
> -	params = hci_conn_params_lookup(hdev, &conn->dst, conn->dst_type);
> -	if (params) {
> -		params->conn_min_interval = min;
> -		params->conn_max_interval = max;
> -		params->conn_latency = latency;
> -		params->supervision_timeout = to_multiplier;
> +	if (!hci_conn_valid(hdev, conn)) {
> +		hci_dev_unlock(hdev);
> +		return -ECANCELED;
>  	}
> -
>  	hci_dev_unlock(hdev);
>  
>  	memset(&cp, 0, sizeof(cp));
>  	cp.handle		= cpu_to_le16(conn->handle);

hci_conn_valid() should be in the same hci_dev_lock() critical section
as where the conn is dereferenced, otherwise the lock is not doing
something useful.

> -	cp.conn_interval_min	= cpu_to_le16(min);
> -	cp.conn_interval_max	= cpu_to_le16(max);
> -	cp.conn_latency		= cpu_to_le16(latency);
> -	cp.supervision_timeout	= cpu_to_le16(to_multiplier);
> +	cp.conn_interval_min	= cpu_to_le16(d->min);
> +	cp.conn_interval_max	= cpu_to_le16(d->max);
> +	cp.conn_latency		= cpu_to_le16(d->latency);
> +	cp.supervision_timeout	= cpu_to_le16(d->to_multiplier);
>  	cp.min_ce_len		= cpu_to_le16(0x0000);
>  	cp.max_ce_len		= cpu_to_le16(0x0000);
>  
> -	hci_send_cmd(hdev, HCI_OP_LE_CONN_UPDATE, sizeof(cp), &cp);
> +	err = __hci_cmd_sync_status_sk(hdev, HCI_OP_LE_CONN_UPDATE,
> +				       sizeof(cp), &cp,
> +				       HCI_EV_LE_CONN_UPDATE_COMPLETE,
> +				       HCI_CMD_TIMEOUT, NULL);
> +	if (err)
> +		return err;
> +
> +	/* Update stored connection parameters after the controller has
> +	 * confirmed the update via the LE Connection Update Complete event.
> +	 */
> +	hci_dev_lock(hdev);
>  
> -	if (params)
> -		return 0x01;
> +	params = hci_conn_params_lookup(hdev, &conn->dst, conn->dst_type);
> +	if (params) {
> +		params->conn_min_interval = d->min;
> +		params->conn_max_interval = d->max;
> +		params->conn_latency = d->latency;
> +		params->supervision_timeout = d->to_multiplier;
> +		store_hint = 0x01;
> +	} else {
> +		store_hint = 0x00;
> +	}
>  
> -	return 0x00;
> +	hci_dev_unlock(hdev);
> +
> +	mgmt_new_conn_param(hdev, &conn->dst, conn->dst_type, store_hint,
> +			    d->min, d->max, d->latency, d->to_multiplier);
> +
> +	return 0;
> +}
> +
> +static void le_conn_update_complete(struct hci_dev *hdev, void *data, int err)
> +{
> +	struct le_conn_update_data *d = data;
> +
> +	hci_conn_put(d->conn);
> +	kfree(d);
> +}
> +
> +void hci_le_conn_update(struct hci_conn *conn, u16 min, u16 max, u16 latency,
> +			u16 to_multiplier)
> +{
> +	struct le_conn_update_data *d;
> +
> +	d = kzalloc_obj(*d);
> +	if (!d)
> +		return;
> +
> +	hci_conn_get(conn);
> +	d->conn = conn;
> +	d->min = min;
> +	d->max = max;
> +	d->latency = latency;
> +	d->to_multiplier = to_multiplier;
> +
> +	if (hci_cmd_sync_queue(conn->hdev, le_conn_update_sync, d,
> +			       le_conn_update_complete) < 0) {
> +		hci_conn_put(conn);
> +		kfree(d);
> +	}
>  }
>  
>  void hci_le_start_enc(struct hci_conn *conn, __le16 ediv, __le64 rand,
> diff --git a/net/bluetooth/l2cap_core.c b/net/bluetooth/l2cap_core.c
> index 95c65fece39b..aac2db1d6fbb 100644
> --- a/net/bluetooth/l2cap_core.c
> +++ b/net/bluetooth/l2cap_core.c
> @@ -4706,16 +4706,8 @@ static inline int l2cap_conn_param_update_req(struct l2cap_conn *conn,
>  	l2cap_send_cmd(conn, cmd->ident, L2CAP_CONN_PARAM_UPDATE_RSP,
>  		       sizeof(rsp), &rsp);
>  
> -	if (!err) {
> -		u8 store_hint;
> -
> -		store_hint = hci_le_conn_update(hcon, min, max, latency,
> -						to_multiplier);
> -		mgmt_new_conn_param(hcon->hdev, &hcon->dst, hcon->dst_type,
> -				    store_hint, min, max, latency,
> -				    to_multiplier);
> -
> -	}
> +	if (!err)
> +		hci_le_conn_update(hcon, min, max, latency, to_multiplier);
>  
>  	return 0;
>  }

Re: [PATCH v4] Bluetooth: l2cap: defer conn param update to avoid conn->lock/hdev->lock inversion

[Luiz Augusto von Dentz]

Hi Mikhail,

On Tue, Apr 14, 2026 at 2:44 PM Mikhail Gavrilov
<mikhail.v.gavrilov@gmail.com> wrote:
>
> When a BLE peripheral sends an L2CAP Connection Parameter Update Request
> the processing path is:
>
>   process_pending_rx()          [takes conn->lock]
>     l2cap_le_sig_channel()
>       l2cap_conn_param_update_req()
>         hci_le_conn_update()    [takes hdev->lock]
>
> Meanwhile other code paths take the locks in the opposite order:
>
>   l2cap_chan_connect()          [takes hdev->lock]
>     ...
>       mutex_lock(&conn->lock)
>
>   l2cap_conn_ready()            [hdev->lock via hci_cb_list_lock]
>     ...
>       mutex_lock(&conn->lock)
>
> This is a classic AB/BA deadlock which lockdep reports as a circular
> locking dependency when connecting a BLE MIDI keyboard (Carry-On FC-49).
>
> Fix this by making hci_le_conn_update() defer the HCI command through
> hci_cmd_sync_queue() so it no longer needs to take hdev->lock in the
> caller context.  The sync callback uses __hci_cmd_sync_status_sk() to
> wait for the HCI_EV_LE_CONN_UPDATE_COMPLETE event, then updates the
> stored connection parameters (hci_conn_params) and notifies userspace
> (mgmt_new_conn_param) only after the controller has confirmed the update.
>
> A reference on hci_conn is held via hci_conn_get()/hci_conn_put() for
> the lifetime of the queued work to prevent use-after-free, and
> hci_conn_valid() is checked before proceeding in case the connection was
> removed while the work was pending.
>
> Fixes: f044eb0524a0 ("Bluetooth: Store latency and supervision timeout in connection params")
> Signed-off-by: Mikhail Gavrilov <mikhail.v.gavrilov@gmail.com>
> Reviewed-by: Paul Menzel <pmenzel@molgen.mpg.de>
> ---
>
> Changes in v4 (Luiz Augusto von Dentz, Sashiko/Gemini AI review):
> - Use hci_conn_get()/hci_conn_put() to hold a reference while work is queued
> - Use __hci_cmd_sync_status_sk() to wait for HCI_EV_LE_CONN_UPDATE_COMPLETE,
>   then do params update + mgmt notification in the sync callback — removes the
>   need for hci_event.c changes and hci_sent_cmd_data()
> - Use kzalloc_obj() per checkpatch recommendation
> - Fix checkpatch alignment issues
>
> Changes in v3 (Luiz Augusto von Dentz):
> - Move hci_cmd_sync_queue into hci_le_conn_update itself instead of open-coding
>   the deferral in l2cap_core.c
> - Move conn_params update and mgmt_new_conn_param into
>   hci_le_conn_update_complete_evt, using hci_sent_cmd_data to retrieve
>   the originally requested parameters
>
> Changes in v2 (Paul Menzel, Sashiko/Gemini AI review):
> - Allocate before sending ACCEPTED response to avoid state mismatch on OOM
> - Verify connection handle and address in sync callback against reuse race
> - Expand commit message with implementation details
>
>  include/net/bluetooth/hci_core.h |  2 +-
>  net/bluetooth/hci_conn.c         | 98 +++++++++++++++++++++++++-------
>  net/bluetooth/l2cap_core.c       | 12 +---
>  3 files changed, 82 insertions(+), 30 deletions(-)
>
> diff --git a/include/net/bluetooth/hci_core.h b/include/net/bluetooth/hci_core.h
> index a7bffb908c1e..aa600fbf9a53 100644
> --- a/include/net/bluetooth/hci_core.h
> +++ b/include/net/bluetooth/hci_core.h
> @@ -2495,7 +2495,7 @@ void mgmt_adv_monitor_device_lost(struct hci_dev *hdev, u16 handle,
>                                   bdaddr_t *bdaddr, u8 addr_type);
>
>  int hci_abort_conn(struct hci_conn *conn, u8 reason);
> -u8 hci_le_conn_update(struct hci_conn *conn, u16 min, u16 max, u16 latency,
> +void hci_le_conn_update(struct hci_conn *conn, u16 min, u16 max, u16 latency,
>                       u16 to_multiplier);
>  void hci_le_start_enc(struct hci_conn *conn, __le16 ediv, __le64 rand,
>                       __u8 ltk[16], __u8 key_size);
> diff --git a/net/bluetooth/hci_conn.c b/net/bluetooth/hci_conn.c
> index 11d3ad8d2551..c9cc18fab1f2 100644
> --- a/net/bluetooth/hci_conn.c
> +++ b/net/bluetooth/hci_conn.c
> @@ -480,40 +480,100 @@ bool hci_setup_sync(struct hci_conn *conn, __u16 handle)
>         return hci_setup_sync_conn(conn, handle);
>  }
>
> -u8 hci_le_conn_update(struct hci_conn *conn, u16 min, u16 max, u16 latency,
> -                     u16 to_multiplier)
> +struct le_conn_update_data {
> +       struct hci_conn *conn;
> +       u16     min;
> +       u16     max;
> +       u16     latency;
> +       u16     to_multiplier;
> +};
> +
> +static int le_conn_update_sync(struct hci_dev *hdev, void *data)
>  {
> -       struct hci_dev *hdev = conn->hdev;
> +       struct le_conn_update_data *d = data;
> +       struct hci_conn *conn = d->conn;
>         struct hci_conn_params *params;
>         struct hci_cp_le_conn_update cp;
> +       u8 store_hint;
> +       int err;
>
> +       /* Verify connection is still alive. */
>         hci_dev_lock(hdev);
> -
> -       params = hci_conn_params_lookup(hdev, &conn->dst, conn->dst_type);
> -       if (params) {
> -               params->conn_min_interval = min;
> -               params->conn_max_interval = max;
> -               params->conn_latency = latency;
> -               params->supervision_timeout = to_multiplier;
> +       if (!hci_conn_valid(hdev, conn)) {
> +               hci_dev_unlock(hdev);
> +               return -ECANCELED;
>         }
> -
>         hci_dev_unlock(hdev);
>
>         memset(&cp, 0, sizeof(cp));
>         cp.handle               = cpu_to_le16(conn->handle);
> -       cp.conn_interval_min    = cpu_to_le16(min);
> -       cp.conn_interval_max    = cpu_to_le16(max);
> -       cp.conn_latency         = cpu_to_le16(latency);
> -       cp.supervision_timeout  = cpu_to_le16(to_multiplier);
> +       cp.conn_interval_min    = cpu_to_le16(d->min);
> +       cp.conn_interval_max    = cpu_to_le16(d->max);
> +       cp.conn_latency         = cpu_to_le16(d->latency);
> +       cp.supervision_timeout  = cpu_to_le16(d->to_multiplier);
>         cp.min_ce_len           = cpu_to_le16(0x0000);
>         cp.max_ce_len           = cpu_to_le16(0x0000);
>
> -       hci_send_cmd(hdev, HCI_OP_LE_CONN_UPDATE, sizeof(cp), &cp);
> +       err = __hci_cmd_sync_status_sk(hdev, HCI_OP_LE_CONN_UPDATE,
> +                                      sizeof(cp), &cp,
> +                                      HCI_EV_LE_CONN_UPDATE_COMPLETE,
> +                                      HCI_CMD_TIMEOUT, NULL);
> +       if (err)
> +               return err;
> +
> +       /* Update stored connection parameters after the controller has
> +        * confirmed the update via the LE Connection Update Complete event.
> +        */
> +       hci_dev_lock(hdev);
>
> -       if (params)
> -               return 0x01;
> +       params = hci_conn_params_lookup(hdev, &conn->dst, conn->dst_type);
> +       if (params) {
> +               params->conn_min_interval = d->min;
> +               params->conn_max_interval = d->max;
> +               params->conn_latency = d->latency;
> +               params->supervision_timeout = d->to_multiplier;
> +               store_hint = 0x01;
> +       } else {
> +               store_hint = 0x00;
> +       }
>
> -       return 0x00;
> +       hci_dev_unlock(hdev);
> +
> +       mgmt_new_conn_param(hdev, &conn->dst, conn->dst_type, store_hint,
> +                           d->min, d->max, d->latency, d->to_multiplier);
> +
> +       return 0;
> +}
> +
> +static void le_conn_update_complete(struct hci_dev *hdev, void *data, int err)
> +{
> +       struct le_conn_update_data *d = data;
> +
> +       hci_conn_put(d->conn);
> +       kfree(d);
> +}
> +
> +void hci_le_conn_update(struct hci_conn *conn, u16 min, u16 max, u16 latency,
> +                       u16 to_multiplier)
> +{
> +       struct le_conn_update_data *d;
> +
> +       d = kzalloc_obj(*d);
> +       if (!d)
> +               return;
> +
> +       hci_conn_get(conn);
> +       d->conn = conn;
> +       d->min = min;
> +       d->max = max;
> +       d->latency = latency;
> +       d->to_multiplier = to_multiplier;
> +
> +       if (hci_cmd_sync_queue(conn->hdev, le_conn_update_sync, d,
> +                              le_conn_update_complete) < 0) {
> +               hci_conn_put(conn);
> +               kfree(d);
> +       }
>  }
>
>  void hci_le_start_enc(struct hci_conn *conn, __le16 ediv, __le64 rand,
> diff --git a/net/bluetooth/l2cap_core.c b/net/bluetooth/l2cap_core.c
> index 95c65fece39b..aac2db1d6fbb 100644
> --- a/net/bluetooth/l2cap_core.c
> +++ b/net/bluetooth/l2cap_core.c
> @@ -4706,16 +4706,8 @@ static inline int l2cap_conn_param_update_req(struct l2cap_conn *conn,
>         l2cap_send_cmd(conn, cmd->ident, L2CAP_CONN_PARAM_UPDATE_RSP,
>                        sizeof(rsp), &rsp);
>
> -       if (!err) {
> -               u8 store_hint;
> -
> -               store_hint = hci_le_conn_update(hcon, min, max, latency,
> -                                               to_multiplier);
> -               mgmt_new_conn_param(hcon->hdev, &hcon->dst, hcon->dst_type,
> -                                   store_hint, min, max, latency,
> -                                   to_multiplier);
> -
> -       }
> +       if (!err)
> +               hci_le_conn_update(hcon, min, max, latency, to_multiplier);
>
>         return 0;
>  }
> --
> 2.53.0

https://sashiko.dev/#/patchset/20260414184415.17114-1-mikhail.v.gavrilov%40gmail.com

1. I don't think it really matters because connection intervals are
typically 60ms at most, so 6*60 = 360ms. That said, perhaps we should
use 6 * max_interval as the timeout since that is how long the
controller has to update the connection interval, well if the 6
consecutive intervals are actually a thing since I don't recall
anything like that being mentioned in the command, but perhaps it is
in the link layer. But if it times out I don't think there is a way to
cancel the change either, so I'm not sure how we'll be able to
synchronize if the controller misbehaves.
2. Well I guess that is would need to defer the response and wait the
HCI proceedure to complete to really respond properly, but that would
mean the remote could get a LL procedure to change the connection
interval before the L2CAP response, so I can see this going wrong
either way.


-- 
Luiz Augusto von Dentz

Re: [PATCH v4] Bluetooth: l2cap: defer conn param update to avoid conn->lock/hdev->lock inversion

[Luiz Augusto von Dentz]

Hi Pauli,

On Tue, Apr 14, 2026 at 4:26 PM Pauli Virtanen <pav@iki.fi> wrote:
>
> ti, 2026-04-14 kello 23:43 +0500, Mikhail Gavrilov kirjoitti:
> > When a BLE peripheral sends an L2CAP Connection Parameter Update Request
> > the processing path is:
> >
> >   process_pending_rx()          [takes conn->lock]
> >     l2cap_le_sig_channel()
> >       l2cap_conn_param_update_req()
> >         hci_le_conn_update()    [takes hdev->lock]
> >
> > Meanwhile other code paths take the locks in the opposite order:
> >
> >   l2cap_chan_connect()          [takes hdev->lock]
> >     ...
> >       mutex_lock(&conn->lock)
> >
> >   l2cap_conn_ready()            [hdev->lock via hci_cb_list_lock]
> >     ...
> >       mutex_lock(&conn->lock)
> >
> > This is a classic AB/BA deadlock which lockdep reports as a circular
> > locking dependency when connecting a BLE MIDI keyboard (Carry-On FC-49).
> >
> > Fix this by making hci_le_conn_update() defer the HCI command through
> > hci_cmd_sync_queue() so it no longer needs to take hdev->lock in the
> > caller context.  The sync callback uses __hci_cmd_sync_status_sk() to
> > wait for the HCI_EV_LE_CONN_UPDATE_COMPLETE event, then updates the
> > stored connection parameters (hci_conn_params) and notifies userspace
> > (mgmt_new_conn_param) only after the controller has confirmed the update.
> >
> > A reference on hci_conn is held via hci_conn_get()/hci_conn_put() for
> > the lifetime of the queued work to prevent use-after-free, and
> > hci_conn_valid() is checked before proceeding in case the connection was
> > removed while the work was pending.
> >
> > Fixes: f044eb0524a0 ("Bluetooth: Store latency and supervision timeout in connection params")
> > Signed-off-by: Mikhail Gavrilov <mikhail.v.gavrilov@gmail.com>
> > Reviewed-by: Paul Menzel <pmenzel@molgen.mpg.de>
> > ---
> >
> > Changes in v4 (Luiz Augusto von Dentz, Sashiko/Gemini AI review):
> > - Use hci_conn_get()/hci_conn_put() to hold a reference while work is queued
> > - Use __hci_cmd_sync_status_sk() to wait for HCI_EV_LE_CONN_UPDATE_COMPLETE,
> >   then do params update + mgmt notification in the sync callback — removes the
> >   need for hci_event.c changes and hci_sent_cmd_data()
> > - Use kzalloc_obj() per checkpatch recommendation
> > - Fix checkpatch alignment issues
> >
> > Changes in v3 (Luiz Augusto von Dentz):
> > - Move hci_cmd_sync_queue into hci_le_conn_update itself instead of open-coding
> >   the deferral in l2cap_core.c
> > - Move conn_params update and mgmt_new_conn_param into
> >   hci_le_conn_update_complete_evt, using hci_sent_cmd_data to retrieve
> >   the originally requested parameters
> >
> > Changes in v2 (Paul Menzel, Sashiko/Gemini AI review):
> > - Allocate before sending ACCEPTED response to avoid state mismatch on OOM
> > - Verify connection handle and address in sync callback against reuse race
> > - Expand commit message with implementation details
> >
> >  include/net/bluetooth/hci_core.h |  2 +-
> >  net/bluetooth/hci_conn.c         | 98 +++++++++++++++++++++++++-------
> >  net/bluetooth/l2cap_core.c       | 12 +---
> >  3 files changed, 82 insertions(+), 30 deletions(-)
> >
> > diff --git a/include/net/bluetooth/hci_core.h b/include/net/bluetooth/hci_core.h
> > index a7bffb908c1e..aa600fbf9a53 100644
> > --- a/include/net/bluetooth/hci_core.h
> > +++ b/include/net/bluetooth/hci_core.h
> > @@ -2495,7 +2495,7 @@ void mgmt_adv_monitor_device_lost(struct hci_dev *hdev, u16 handle,
> >                                 bdaddr_t *bdaddr, u8 addr_type);
> >
> >  int hci_abort_conn(struct hci_conn *conn, u8 reason);
> > -u8 hci_le_conn_update(struct hci_conn *conn, u16 min, u16 max, u16 latency,
> > +void hci_le_conn_update(struct hci_conn *conn, u16 min, u16 max, u16 latency,
> >                     u16 to_multiplier);
> >  void hci_le_start_enc(struct hci_conn *conn, __le16 ediv, __le64 rand,
> >                     __u8 ltk[16], __u8 key_size);
> > diff --git a/net/bluetooth/hci_conn.c b/net/bluetooth/hci_conn.c
> > index 11d3ad8d2551..c9cc18fab1f2 100644
> > --- a/net/bluetooth/hci_conn.c
> > +++ b/net/bluetooth/hci_conn.c
> > @@ -480,40 +480,100 @@ bool hci_setup_sync(struct hci_conn *conn, __u16 handle)
> >       return hci_setup_sync_conn(conn, handle);
> >  }
> >
> > -u8 hci_le_conn_update(struct hci_conn *conn, u16 min, u16 max, u16 latency,
> > -                   u16 to_multiplier)
> > +struct le_conn_update_data {
> > +     struct hci_conn *conn;
> > +     u16     min;
> > +     u16     max;
> > +     u16     latency;
> > +     u16     to_multiplier;
> > +};
> > +
> > +static int le_conn_update_sync(struct hci_dev *hdev, void *data)
> >  {
> > -     struct hci_dev *hdev = conn->hdev;
> > +     struct le_conn_update_data *d = data;
> > +     struct hci_conn *conn = d->conn;
> >       struct hci_conn_params *params;
> >       struct hci_cp_le_conn_update cp;
> > +     u8 store_hint;
> > +     int err;
> >
> > +     /* Verify connection is still alive. */
> >       hci_dev_lock(hdev);
> > -
> > -     params = hci_conn_params_lookup(hdev, &conn->dst, conn->dst_type);
> > -     if (params) {
> > -             params->conn_min_interval = min;
> > -             params->conn_max_interval = max;
> > -             params->conn_latency = latency;
> > -             params->supervision_timeout = to_multiplier;
> > +     if (!hci_conn_valid(hdev, conn)) {
> > +             hci_dev_unlock(hdev);
> > +             return -ECANCELED;
> >       }
> > -
> >       hci_dev_unlock(hdev);
> >
> >       memset(&cp, 0, sizeof(cp));
> >       cp.handle               = cpu_to_le16(conn->handle);
>
> hci_conn_valid() should be in the same hci_dev_lock() critical section
> as where the conn is dereferenced, otherwise the lock is not doing
> something useful.

This means we should only unlock after we finish using hci_conn,
including conn->handle above.

> > -     cp.conn_interval_min    = cpu_to_le16(min);
> > -     cp.conn_interval_max    = cpu_to_le16(max);
> > -     cp.conn_latency         = cpu_to_le16(latency);
> > -     cp.supervision_timeout  = cpu_to_le16(to_multiplier);
> > +     cp.conn_interval_min    = cpu_to_le16(d->min);
> > +     cp.conn_interval_max    = cpu_to_le16(d->max);
> > +     cp.conn_latency         = cpu_to_le16(d->latency);
> > +     cp.supervision_timeout  = cpu_to_le16(d->to_multiplier);
> >       cp.min_ce_len           = cpu_to_le16(0x0000);
> >       cp.max_ce_len           = cpu_to_le16(0x0000);
> >
> > -     hci_send_cmd(hdev, HCI_OP_LE_CONN_UPDATE, sizeof(cp), &cp);
> > +     err = __hci_cmd_sync_status_sk(hdev, HCI_OP_LE_CONN_UPDATE,
> > +                                    sizeof(cp), &cp,
> > +                                    HCI_EV_LE_CONN_UPDATE_COMPLETE,
> > +                                    HCI_CMD_TIMEOUT, NULL);
> > +     if (err)
> > +             return err;
> > +
> > +     /* Update stored connection parameters after the controller has
> > +      * confirmed the update via the LE Connection Update Complete event.
> > +      */
> > +     hci_dev_lock(hdev);
> >
> > -     if (params)
> > -             return 0x01;
> > +     params = hci_conn_params_lookup(hdev, &conn->dst, conn->dst_type);
> > +     if (params) {
> > +             params->conn_min_interval = d->min;
> > +             params->conn_max_interval = d->max;
> > +             params->conn_latency = d->latency;
> > +             params->supervision_timeout = d->to_multiplier;
> > +             store_hint = 0x01;
> > +     } else {
> > +             store_hint = 0x00;
> > +     }
> >
> > -     return 0x00;
> > +     hci_dev_unlock(hdev);
> > +
> > +     mgmt_new_conn_param(hdev, &conn->dst, conn->dst_type, store_hint,
> > +                         d->min, d->max, d->latency, d->to_multiplier);
> > +
> > +     return 0;
> > +}
> > +
> > +static void le_conn_update_complete(struct hci_dev *hdev, void *data, int err)
> > +{
> > +     struct le_conn_update_data *d = data;
> > +
> > +     hci_conn_put(d->conn);
> > +     kfree(d);
> > +}
> > +
> > +void hci_le_conn_update(struct hci_conn *conn, u16 min, u16 max, u16 latency,
> > +                     u16 to_multiplier)
> > +{
> > +     struct le_conn_update_data *d;
> > +
> > +     d = kzalloc_obj(*d);
> > +     if (!d)
> > +             return;
> > +
> > +     hci_conn_get(conn);
> > +     d->conn = conn;
> > +     d->min = min;
> > +     d->max = max;
> > +     d->latency = latency;
> > +     d->to_multiplier = to_multiplier;
> > +
> > +     if (hci_cmd_sync_queue(conn->hdev, le_conn_update_sync, d,
> > +                            le_conn_update_complete) < 0) {
> > +             hci_conn_put(conn);
> > +             kfree(d);
> > +     }
> >  }
> >
> >  void hci_le_start_enc(struct hci_conn *conn, __le16 ediv, __le64 rand,
> > diff --git a/net/bluetooth/l2cap_core.c b/net/bluetooth/l2cap_core.c
> > index 95c65fece39b..aac2db1d6fbb 100644
> > --- a/net/bluetooth/l2cap_core.c
> > +++ b/net/bluetooth/l2cap_core.c
> > @@ -4706,16 +4706,8 @@ static inline int l2cap_conn_param_update_req(struct l2cap_conn *conn,
> >       l2cap_send_cmd(conn, cmd->ident, L2CAP_CONN_PARAM_UPDATE_RSP,
> >                      sizeof(rsp), &rsp);
> >
> > -     if (!err) {
> > -             u8 store_hint;
> > -
> > -             store_hint = hci_le_conn_update(hcon, min, max, latency,
> > -                                             to_multiplier);
> > -             mgmt_new_conn_param(hcon->hdev, &hcon->dst, hcon->dst_type,
> > -                                 store_hint, min, max, latency,
> > -                                 to_multiplier);
> > -
> > -     }
> > +     if (!err)
> > +             hci_le_conn_update(hcon, min, max, latency, to_multiplier);
> >
> >       return 0;
> >  }



-- 
Luiz Augusto von Dentz