The HCI command, event, and data packet processing workqueue is drained
to avoid deadlock in commit
76727c02c1e1 ("Bluetooth: Call drain_workqueue() before resetting state").
There is another delayed work, which will queue command to this drained
workqueue. Which results in the following error report:
Bluetooth: hci2: command 0x040f tx timeout
WARNING: CPU: 1 PID: 18374 at kernel/workqueue.c:1438 __queue_work+0xdad/0x1140
Workqueue: events hci_cmd_timeout
RIP: 0010:__queue_work+0xdad/0x1140
RSP: 0000:ffffc90002cffc60 EFLAGS: 00010093
RAX: 0000000000000000 RBX: ffff8880b9d3ec00 RCX: 0000000000000000
RDX: ffff888024ba0000 RSI: ffffffff814e048d RDI: ffff8880b9d3ec08
RBP: 0000000000000008 R08: 0000000000000000 R09: 00000000b9d39700
R10: ffffffff814f73c6 R11: 0000000000000000 R12: ffff88807cce4c60
R13: 0000000000000000 R14: ffff8880796d8800 R15: ffff8880796d8800
FS: 0000000000000000(0000) GS:ffff8880b9d00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000c0174b4000 CR3: 000000007cae9000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<TASK>
? queue_work_on+0xcb/0x110
? lockdep_hardirqs_off+0x90/0xd0
queue_work_on+0xee/0x110
process_one_work+0x996/0x1610
? pwq_dec_nr_in_flight+0x2a0/0x2a0
? rwlock_bug.part.0+0x90/0x90
? _raw_spin_lock_irq+0x41/0x50
worker_thread+0x665/0x1080
? process_one_work+0x1610/0x1610
kthread+0x2e9/0x3a0
? kthread_complete_and_exit+0x40/0x40
ret_from_fork+0x1f/0x30
</TASK>
To fix this, we can add a new HCI_DRAIN_WQ flag, and don't queue the
timeout workqueue while command workqueue is draining.
Fixes: 76727c02c1e1 ("Bluetooth: Call drain_workqueue() before resetting state")
Reported-by: [email protected]
Signed-off-by: Schspa Shi <[email protected]>
Changelog:
v1 -> v2:
- Move the workqueue drain flag to controller flags, and
use hci_dev_*_flag.
- Add missing ncmd_timer cancel.
- Clear DRAIN_WORKQUEUE flag after device command flushed.
v2 -> v3:
- Fix typos in comments and adjust the description.
---
include/net/bluetooth/hci.h | 1 +
net/bluetooth/hci_core.c | 10 +++++++++-
net/bluetooth/hci_event.c | 5 +++--
3 files changed, 13 insertions(+), 3 deletions(-)
diff --git a/include/net/bluetooth/hci.h b/include/net/bluetooth/hci.h
index fe7935be7dc4..4a45c48eb0d2 100644
--- a/include/net/bluetooth/hci.h
+++ b/include/net/bluetooth/hci.h
@@ -361,6 +361,7 @@ enum {
HCI_QUALITY_REPORT,
HCI_OFFLOAD_CODECS_ENABLED,
HCI_LE_SIMULTANEOUS_ROLES,
+ HCI_CMD_DRAIN_WORKQUEUE,
__HCI_NUM_FLAGS,
};
diff --git a/net/bluetooth/hci_core.c b/net/bluetooth/hci_core.c
index 5abb2ca5b129..8539b4233da8 100644
--- a/net/bluetooth/hci_core.c
+++ b/net/bluetooth/hci_core.c
@@ -593,6 +593,11 @@ static int hci_dev_do_reset(struct hci_dev *hdev)
skb_queue_purge(&hdev->rx_q);
skb_queue_purge(&hdev->cmd_q);
+ /* Cancel these to avoid queueing non-chained pending work */
+ hci_dev_set_flag(hdev, HCI_CMD_DRAIN_WORKQUEUE);
+ cancel_delayed_work(&hdev->cmd_timer);
+ cancel_delayed_work(&hdev->ncmd_timer);
+
/* Avoid potential lockdep warnings from the *_flush() calls by
* ensuring the workqueue is empty up front.
*/
@@ -606,6 +611,8 @@ static int hci_dev_do_reset(struct hci_dev *hdev)
if (hdev->flush)
hdev->flush(hdev);
+ hci_dev_clear_flag(hdev, HCI_CMD_DRAIN_WORKQUEUE);
+
atomic_set(&hdev->cmd_cnt, 1);
hdev->acl_cnt = 0; hdev->sco_cnt = 0; hdev->le_cnt = 0;
@@ -3861,7 +3868,8 @@ static void hci_cmd_work(struct work_struct *work)
if (res < 0)
__hci_cmd_sync_cancel(hdev, -res);
- if (test_bit(HCI_RESET, &hdev->flags))
+ if (test_bit(HCI_RESET, &hdev->flags) ||
+ hci_dev_test_flag(hdev, HCI_CMD_DRAIN_WORKQUEUE))
cancel_delayed_work(&hdev->cmd_timer);
else
schedule_delayed_work(&hdev->cmd_timer,
diff --git a/net/bluetooth/hci_event.c b/net/bluetooth/hci_event.c
index af17dfb20e01..7cb956d3abb2 100644
--- a/net/bluetooth/hci_event.c
+++ b/net/bluetooth/hci_event.c
@@ -3768,8 +3768,9 @@ static inline void handle_cmd_cnt_and_timer(struct hci_dev *hdev, u8 ncmd)
cancel_delayed_work(&hdev->ncmd_timer);
atomic_set(&hdev->cmd_cnt, 1);
} else {
- schedule_delayed_work(&hdev->ncmd_timer,
- HCI_NCMD_TIMEOUT);
+ if (!hci_dev_test_flag(hdev, HCI_CMD_DRAIN_WORKQUEUE))
+ schedule_delayed_work(&hdev->ncmd_timer,
+ HCI_NCMD_TIMEOUT);
}
}
}
--
2.24.3 (Apple Git-128)
Hello:
This patch was applied to bluetooth/bluetooth-next.git (master)
by Marcel Holtmann <[email protected]>:
On Fri, 3 Jun 2022 16:19:14 +0800 you wrote:
> The HCI command, event, and data packet processing workqueue is drained
> to avoid deadlock in commit
> 76727c02c1e1 ("Bluetooth: Call drain_workqueue() before resetting state").
>
> There is another delayed work, which will queue command to this drained
> workqueue. Which results in the following error report:
>
> [...]
Here is the summary with links:
- [v3] Bluetooth: When HCI work queue is drained, only queue chained work
https://git.kernel.org/bluetooth/bluetooth-next/c/dba7abaead13
You are awesome, thank you!
--
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