[PATCH v2] Bluetooth: Cancel le_scan_restart work when stopping discovery

[PATCH v2] Bluetooth: Cancel le_scan_restart work when stopping discovery

[Sonny Sasaka]

Not cancelling it has caused a bug where passive background scanning is
disabled out of the blue, preventing BLE keyboards/mice to reconnect.
Here is how it happens:
After hci_req_stop_discovery, there is still le_scan_restart_work
scheduled. Invocation of le_scan_restart_work causes a harmful
le_scan_disable_work to be scheduled. This le_scan_disable_work will
eventually disable passive scanning when the timer fires.

Sample btmon trace:

< HCI Command: LE Set Scan Parameters (0x08|0x000b) plen 7
        Type: Passive (0x00)
        Interval: 367.500 msec (0x024c)
        Window: 37.500 msec (0x003c)
        Own address type: Public (0x00)
        Filter policy: Accept all advertisement (0x00)
> HCI Event: Command Complete (0x0e) plen 4
      LE Set Scan Parameters (0x08|0x000b) ncmd 1
        Status: Success (0x00)
< HCI Command: LE Set Scan Enable (0x08|0x000c) plen 2
        Scanning: Enabled (0x01)
        Filter duplicates: Disabled (0x00)
> HCI Event: Command Complete (0x0e) plen 4
      LE Set Scan Enable (0x08|0x000c) ncmd 2
        Status: Success (0x00)
...
< HCI Command: LE Set Scan Enable (0x08|0x000c) plen 2
        Scanning: Disabled (0x00)
        Filter duplicates: Disabled (0x00)
> HCI Event: Command Complete (0x0e) plen 4
      LE Set Scan Enable (0x08|0x000c) ncmd 2
        Status: Success (0x00)
// Background scanning is not working here onwards.

Reviewed-by: Abhishek Pandit-Subedi <abhishekpandit@chromium.org>
Signed-off-by: Sonny Sasaka <sonnysasaka@chromium.org>

---
 net/bluetooth/hci_request.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/net/bluetooth/hci_request.c b/net/bluetooth/hci_request.c
index d7ee11ef70d3e..8ace5d34b01ef 100644
--- a/net/bluetooth/hci_request.c
+++ b/net/bluetooth/hci_request.c
@@ -3252,6 +3252,7 @@ bool hci_req_stop_discovery(struct hci_request *req)
 
 		if (hci_dev_test_flag(hdev, HCI_LE_SCAN)) {
 			cancel_delayed_work(&hdev->le_scan_disable);
+			cancel_delayed_work(&hdev->le_scan_restart);
 			hci_req_add_le_scan_disable(req, false);
 		}
 
-- 
2.29.2

RE: [v2] Bluetooth: Cancel le_scan_restart work when stopping discovery

[bluez.test.bot]

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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=448487

---Test result---

##############################
    Test: CheckPatch - PASS
    

    ##############################
    Test: CheckGitLint - PASS
    

    ##############################
    Test: CheckBuildK - PASS
    

    ##############################
    Test: CheckTestRunner: Setup - PASS
    

    ##############################
    Test: CheckTestRunner: l2cap-tester - PASS
    Total: 40, Passed: 34 (85.0%), Failed: 0, Not Run: 6

    ##############################
    Test: CheckTestRunner: bnep-tester - PASS
    Total: 1, Passed: 1 (100.0%), Failed: 0, Not Run: 0

    ##############################
    Test: CheckTestRunner: mgmt-tester - FAIL
    Total: 416, Passed: 397 (95.4%), Failed: 3, Not Run: 16

    ##############################
    Test: CheckTestRunner: rfcomm-tester - PASS
    Total: 9, Passed: 9 (100.0%), Failed: 0, Not Run: 0

    ##############################
    Test: CheckTestRunner: sco-tester - PASS
    Total: 8, Passed: 8 (100.0%), Failed: 0, Not Run: 0

    ##############################
    Test: CheckTestRunner: smp-tester - PASS
    Total: 8, Passed: 8 (100.0%), Failed: 0, Not Run: 0

    ##############################
    Test: CheckTestRunner: userchan-tester - PASS
    Total: 3, Passed: 3 (100.0%), Failed: 0, Not Run: 0

    

---
Regards,
Linux Bluetooth


[-- Attachment #2: l2cap-tester.log --]
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[-- Attachment #4: mgmt-tester.log --]
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[-- Attachment #5: rfcomm-tester.log --]
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[-- Attachment #6: sco-tester.log --]
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[-- Attachment #7: smp-tester.log --]
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[-- Attachment #8: userchan-tester.log --]
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Re: [PATCH v2] Bluetooth: Cancel le_scan_restart work when stopping discovery

[Marcel Holtmann]

Hi Sonny,

> Not cancelling it has caused a bug where passive background scanning is
> disabled out of the blue, preventing BLE keyboards/mice to reconnect.
> Here is how it happens:
> After hci_req_stop_discovery, there is still le_scan_restart_work
> scheduled. Invocation of le_scan_restart_work causes a harmful
> le_scan_disable_work to be scheduled. This le_scan_disable_work will
> eventually disable passive scanning when the timer fires.
> 
> Sample btmon trace:
> 
> < HCI Command: LE Set Scan Parameters (0x08|0x000b) plen 7
>        Type: Passive (0x00)
>        Interval: 367.500 msec (0x024c)
>        Window: 37.500 msec (0x003c)
>        Own address type: Public (0x00)
>        Filter policy: Accept all advertisement (0x00)
>> HCI Event: Command Complete (0x0e) plen 4
>      LE Set Scan Parameters (0x08|0x000b) ncmd 1
>        Status: Success (0x00)
> < HCI Command: LE Set Scan Enable (0x08|0x000c) plen 2
>        Scanning: Enabled (0x01)
>        Filter duplicates: Disabled (0x00)
>> HCI Event: Command Complete (0x0e) plen 4
>      LE Set Scan Enable (0x08|0x000c) ncmd 2
>        Status: Success (0x00)
> ...
> < HCI Command: LE Set Scan Enable (0x08|0x000c) plen 2
>        Scanning: Disabled (0x00)
>        Filter duplicates: Disabled (0x00)
>> HCI Event: Command Complete (0x0e) plen 4
>      LE Set Scan Enable (0x08|0x000c) ncmd 2
>        Status: Success (0x00)
> // Background scanning is not working here onwards.
> 
> Reviewed-by: Abhishek Pandit-Subedi <abhishekpandit@chromium.org>
> Signed-off-by: Sonny Sasaka <sonnysasaka@chromium.org>
> 
> ---
> net/bluetooth/hci_request.c | 1 +
> 1 file changed, 1 insertion(+)

patch has been applied to bluetooth-next tree.

Regards

Marcel