* [PATCH v3] Bluetooth: l2cap: defer conn param update to avoid conn->lock/hdev->lock inversion
@ 2026-04-13 23:08 Mikhail Gavrilov
2026-04-13 23:52 ` [v3] " bluez.test.bot
2026-04-14 14:46 ` [PATCH v3] " Luiz Augusto von Dentz
0 siblings, 2 replies; 3+ messages in thread
From: Mikhail Gavrilov @ 2026-04-13 23:08 UTC (permalink / raw)
To: luiz.dentz, marcel
Cc: pmenzel, linux-bluetooth, linux-kernel, 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 connection parameter storage (hci_conn_params update) and userspace
notification (mgmt_new_conn_param) are moved into
hci_le_conn_update_complete_evt() where they are handled when the
controller confirms the update, using hci_sent_cmd_data() to retrieve
the originally requested min/max interval values.
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 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 | 66 ++++++++++++++++++++++----------
net/bluetooth/hci_event.c | 33 ++++++++++++++++
net/bluetooth/l2cap_core.c | 12 +-----
4 files changed, 81 insertions(+), 32 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..207221560a02 100644
--- a/net/bluetooth/hci_conn.c
+++ b/net/bluetooth/hci_conn.c
@@ -480,40 +480,64 @@ 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 hci_conn_params *params;
+ struct le_conn_update_data *d = data;
+ struct hci_conn *conn;
struct hci_cp_le_conn_update cp;
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;
- }
-
+ /* Verify connection is still alive. */
+ conn = hci_conn_valid(hdev, d->conn) ? d->conn : NULL;
hci_dev_unlock(hdev);
+ if (!conn)
+ return -ECANCELED;
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);
+ return __hci_cmd_sync_status(hdev, HCI_OP_LE_CONN_UPDATE,
+ sizeof(cp), &cp, HCI_CMD_TIMEOUT);
+}
+
+static void le_conn_update_complete(struct hci_dev *hdev, void *data,
+ int err)
+{
+ kfree(data);
+}
- if (params)
- return 0x01;
+void hci_le_conn_update(struct hci_conn *conn, u16 min, u16 max, u16 latency,
+ u16 to_multiplier)
+{
+ struct le_conn_update_data *d;
- return 0x00;
+ d = kmalloc(sizeof(*d), GFP_KERNEL);
+ if (!d)
+ return;
+
+ 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)
+ kfree(d);
}
void hci_le_start_enc(struct hci_conn *conn, __le16 ediv, __le64 rand,
diff --git a/net/bluetooth/hci_event.c b/net/bluetooth/hci_event.c
index 3ebc5e6d45d9..9df8fc762a84 100644
--- a/net/bluetooth/hci_event.c
+++ b/net/bluetooth/hci_event.c
@@ -6065,6 +6065,8 @@ static void hci_le_conn_update_complete_evt(struct hci_dev *hdev, void *data,
struct sk_buff *skb)
{
struct hci_ev_le_conn_update_complete *ev = data;
+ struct hci_cp_le_conn_update *sent;
+ struct hci_conn_params *params;
struct hci_conn *conn;
bt_dev_dbg(hdev, "status 0x%2.2x", ev->status);
@@ -6079,6 +6081,37 @@ static void hci_le_conn_update_complete_evt(struct hci_dev *hdev, void *data,
conn->le_conn_interval = le16_to_cpu(ev->interval);
conn->le_conn_latency = le16_to_cpu(ev->latency);
conn->le_supv_timeout = le16_to_cpu(ev->supervision_timeout);
+
+ /* Update stored connection parameters and notify userspace
+ * using the parameters from the original HCI command.
+ */
+ sent = hci_sent_cmd_data(hdev, HCI_OP_LE_CONN_UPDATE);
+ if (sent) {
+ u8 store_hint;
+
+ params = hci_conn_params_lookup(hdev, &conn->dst,
+ conn->dst_type);
+ if (params) {
+ params->conn_min_interval =
+ le16_to_cpu(sent->conn_interval_min);
+ params->conn_max_interval =
+ le16_to_cpu(sent->conn_interval_max);
+ params->conn_latency =
+ le16_to_cpu(sent->conn_latency);
+ params->supervision_timeout =
+ le16_to_cpu(sent->supervision_timeout);
+ store_hint = 0x01;
+ } else {
+ store_hint = 0x00;
+ }
+
+ mgmt_new_conn_param(hdev, &conn->dst, conn->dst_type,
+ store_hint,
+ le16_to_cpu(sent->conn_interval_min),
+ le16_to_cpu(sent->conn_interval_max),
+ le16_to_cpu(sent->conn_latency),
+ le16_to_cpu(sent->supervision_timeout));
+ }
}
hci_dev_unlock(hdev);
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
^ permalink raw reply related [flat|nested] 3+ messages in thread
* RE: [v3] Bluetooth: l2cap: defer conn param update to avoid conn->lock/hdev->lock inversion
2026-04-13 23:08 [PATCH v3] Bluetooth: l2cap: defer conn param update to avoid conn->lock/hdev->lock inversion Mikhail Gavrilov
@ 2026-04-13 23:52 ` bluez.test.bot
2026-04-14 14:46 ` [PATCH v3] " Luiz Augusto von Dentz
1 sibling, 0 replies; 3+ messages in thread
From: bluez.test.bot @ 2026-04-13 23:52 UTC (permalink / raw)
To: linux-bluetooth, mikhail.v.gavrilov
[-- Attachment #1: Type: text/plain, Size: 8839 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=1080906
---Test result---
Test Summary:
CheckPatch FAIL 1.25 seconds
GitLint FAIL 0.21 seconds
SubjectPrefix PASS 0.06 seconds
BuildKernel PASS 26.15 seconds
CheckAllWarning PASS 33.68 seconds
CheckSparse PASS 28.46 seconds
BuildKernel32 PASS 25.26 seconds
TestRunnerSetup PASS 575.60 seconds
TestRunner_l2cap-tester PASS 28.18 seconds
TestRunner_iso-tester PASS 36.67 seconds
TestRunner_bnep-tester PASS 6.46 seconds
TestRunner_mgmt-tester FAIL 114.28 seconds
TestRunner_rfcomm-tester PASS 9.52 seconds
TestRunner_sco-tester FAIL 14.08 seconds
TestRunner_ioctl-tester PASS 10.36 seconds
TestRunner_mesh-tester FAIL 12.22 seconds
TestRunner_smp-tester PASS 8.67 seconds
TestRunner_userchan-tester PASS 6.72 seconds
TestRunner_6lowpan-tester FAIL 8.48 seconds
IncrementalBuild FAIL 1.35 seconds
Details
##############################
Test: CheckPatch - FAIL
Desc: Run checkpatch.pl script
Output:
[v3] Bluetooth: l2cap: defer conn param update to avoid conn->lock/hdev->lock inversion
CHECK: Alignment should match open parenthesis
#229: FILE: net/bluetooth/hci_conn.c:518:
+static void le_conn_update_complete(struct hci_dev *hdev, void *data,
+ int err)
ERROR: code indent should use tabs where possible
#237: FILE: net/bluetooth/hci_conn.c:524:
+^I^I u16 to_multiplier)$
CHECK: Alignment should match open parenthesis
#237: FILE: net/bluetooth/hci_conn.c:524:
+void hci_le_conn_update(struct hci_conn *conn, u16 min, u16 max, u16 latency,
+ u16 to_multiplier)
WARNING: Prefer kmalloc_obj over kmalloc with sizeof
#242: FILE: net/bluetooth/hci_conn.c:528:
+ d = kmalloc(sizeof(*d), GFP_KERNEL);
total: 1 errors, 1 warnings, 2 checks, 156 lines checked
NOTE: For some of the reported defects, checkpatch may be able to
mechanically convert to the typical style using --fix or --fix-inplace.
NOTE: Whitespace errors detected.
You may wish to use scripts/cleanpatch or scripts/cleanfile
/github/workspace/src/patch/14523623.patch has style problems, please review.
NOTE: Ignored message types: UNKNOWN_COMMIT_ID
NOTE: If any of the errors are false positives, please report
them to the maintainer, see CHECKPATCH in MAINTAINERS.
##############################
Test: GitLint - FAIL
Desc: Run gitlint
Output:
[v3] 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): "[v3] Bluetooth: l2cap: defer conn param update to avoid conn->lock/hdev->lock inversion"
44: 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 0.109 seconds
##############################
Test: TestRunner_sco-tester - FAIL
Desc: Run sco-tester with test-runner
Output:
WARNING: possible circular locking dependency detected
7.0.0-rc2-gea668f64ba2a #1 Not tainted
------------------------------------------------------
kworker/u5:2/117 is trying to acquire lock:
ffff8880021b6240 (sk_lock-AF_BLUETOOTH-BTPROTO_SCO){+.+.}-{0:0}, at: sco_connect_cfm+0x358/0x8d0
but task is already holding lock:
ffff8880025f8220 (&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-gea668f64ba2a #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 2.640 seconds
Mesh - Send cancel - 2 Timed out 1.996 seconds
##############################
Test: TestRunner_6lowpan-tester - FAIL
Desc: Run 6lowpan-tester with test-runner
Output:
WARNING: possible circular locking dependency detected
7.0.0-rc2-gea668f64ba2a #1 Not tainted
------------------------------------------------------
kworker/0:1/11 is trying to acquire lock:
ffff8880026e0940 ((wq_completion)hci0#2){+.+.}-{0:0}, at: touch_wq_lockdep_map+0x75/0x180
but task is already holding lock:
ffffffff8fa4d720 (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:
fatal: previous rebase directory .git/rebase-apply still exists but mbox given.
https://github.com/bluez/bluetooth-next/pull/80
---
Regards,
Linux Bluetooth
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH v3] Bluetooth: l2cap: defer conn param update to avoid conn->lock/hdev->lock inversion
2026-04-13 23:08 [PATCH v3] Bluetooth: l2cap: defer conn param update to avoid conn->lock/hdev->lock inversion Mikhail Gavrilov
2026-04-13 23:52 ` [v3] " bluez.test.bot
@ 2026-04-14 14:46 ` Luiz Augusto von Dentz
1 sibling, 0 replies; 3+ messages in thread
From: Luiz Augusto von Dentz @ 2026-04-14 14:46 UTC (permalink / raw)
To: Mikhail Gavrilov; +Cc: marcel, pmenzel, linux-bluetooth, linux-kernel
Hi Mikhail,
On Mon, Apr 13, 2026 at 7:08 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 connection parameter storage (hci_conn_params update) and userspace
> notification (mgmt_new_conn_param) are moved into
> hci_le_conn_update_complete_evt() where they are handled when the
> controller confirms the update, using hci_sent_cmd_data() to retrieve
> the originally requested min/max interval values.
>
> 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 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 | 66 ++++++++++++++++++++++----------
> net/bluetooth/hci_event.c | 33 ++++++++++++++++
> net/bluetooth/l2cap_core.c | 12 +-----
> 4 files changed, 81 insertions(+), 32 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..207221560a02 100644
> --- a/net/bluetooth/hci_conn.c
> +++ b/net/bluetooth/hci_conn.c
> @@ -480,40 +480,64 @@ 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 hci_conn_params *params;
> + struct le_conn_update_data *d = data;
> + struct hci_conn *conn;
> struct hci_cp_le_conn_update cp;
>
> 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;
> - }
> -
> + /* Verify connection is still alive. */
> + conn = hci_conn_valid(hdev, d->conn) ? d->conn : NULL;
> hci_dev_unlock(hdev);
> + if (!conn)
> + return -ECANCELED;
>
> 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);
> + return __hci_cmd_sync_status(hdev, HCI_OP_LE_CONN_UPDATE,
> + sizeof(cp), &cp, HCI_CMD_TIMEOUT);
> +}
> +
> +static void le_conn_update_complete(struct hci_dev *hdev, void *data,
> + int err)
> +{
> + kfree(data);
> +}
>
> - if (params)
> - return 0x01;
> +void hci_le_conn_update(struct hci_conn *conn, u16 min, u16 max, u16 latency,
> + u16 to_multiplier)
> +{
> + struct le_conn_update_data *d;
>
> - return 0x00;
> + d = kmalloc(sizeof(*d), GFP_KERNEL);
> + if (!d)
> + return;
> +
> + 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)
> + kfree(d);
> }
>
> void hci_le_start_enc(struct hci_conn *conn, __le16 ediv, __le64 rand,
> diff --git a/net/bluetooth/hci_event.c b/net/bluetooth/hci_event.c
> index 3ebc5e6d45d9..9df8fc762a84 100644
> --- a/net/bluetooth/hci_event.c
> +++ b/net/bluetooth/hci_event.c
> @@ -6065,6 +6065,8 @@ static void hci_le_conn_update_complete_evt(struct hci_dev *hdev, void *data,
> struct sk_buff *skb)
> {
> struct hci_ev_le_conn_update_complete *ev = data;
> + struct hci_cp_le_conn_update *sent;
> + struct hci_conn_params *params;
> struct hci_conn *conn;
>
> bt_dev_dbg(hdev, "status 0x%2.2x", ev->status);
> @@ -6079,6 +6081,37 @@ static void hci_le_conn_update_complete_evt(struct hci_dev *hdev, void *data,
> conn->le_conn_interval = le16_to_cpu(ev->interval);
> conn->le_conn_latency = le16_to_cpu(ev->latency);
> conn->le_supv_timeout = le16_to_cpu(ev->supervision_timeout);
> +
> + /* Update stored connection parameters and notify userspace
> + * using the parameters from the original HCI command.
> + */
> + sent = hci_sent_cmd_data(hdev, HCI_OP_LE_CONN_UPDATE);
> + if (sent) {
> + u8 store_hint;
> +
> + params = hci_conn_params_lookup(hdev, &conn->dst,
> + conn->dst_type);
> + if (params) {
> + params->conn_min_interval =
> + le16_to_cpu(sent->conn_interval_min);
> + params->conn_max_interval =
> + le16_to_cpu(sent->conn_interval_max);
> + params->conn_latency =
> + le16_to_cpu(sent->conn_latency);
> + params->supervision_timeout =
> + le16_to_cpu(sent->supervision_timeout);
> + store_hint = 0x01;
> + } else {
> + store_hint = 0x00;
> + }
> +
> + mgmt_new_conn_param(hdev, &conn->dst, conn->dst_type,
> + store_hint,
> + le16_to_cpu(sent->conn_interval_min),
> + le16_to_cpu(sent->conn_interval_max),
> + le16_to_cpu(sent->conn_latency),
> + le16_to_cpu(sent->supervision_timeout));
> + }
> }
>
> hci_dev_unlock(hdev);
> 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/20260413230813.21393-1-mikhail.v.gavrilov%40gmail.com
Most comments seem valid. Regarding the last 2 we might need to wait
for HCI_EV_LE_CONN_UPDATE_COMPLETE by passing it to
__hci_cmd_sync_status_sk.
For the first comment I guess we will need to use hci_conn_get to
prevent the hci_conn from being freed. It can still be removed so the
usage of hci_conn_valid remains valid, but we will need to call
hci_conn_put even if hci_conn is already removed.
--
Luiz Augusto von Dentz
^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2026-04-14 14:46 UTC | newest]
Thread overview: 3+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2026-04-13 23:08 [PATCH v3] Bluetooth: l2cap: defer conn param update to avoid conn->lock/hdev->lock inversion Mikhail Gavrilov
2026-04-13 23:52 ` [v3] " bluez.test.bot
2026-04-14 14:46 ` [PATCH v3] " Luiz Augusto von Dentz
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