Re: Memory leak in btusb

[Larry Finger <Larry.Finger@lwfinger.net>]

On 06/06/2015 01:31 PM, Marcel Holtmann wrote:
> Hi Larry,
>
> since the interrupt endpoint is only used for HCI events, you do not even need connections. This could be anything simple like HCI command complete event.
>
> Now I wonder if this is something odd where the HCI event fits completely into a single interrupt URB or something special like that. If you get get the content of that URB, then I might be able to track this down. Or do you have a chance to run btmon and correlate the timestamps.

Synchronizing the timing between kmemleak and btmon is a little difficult as the 
former reports time only in jiffies and seconds before present. I will keep 
looking, but I think the leaked allocation happened at roughly 16:17:52. The 
only things that btmon logged are

> HCI Event: Number of Completed Packets (0x13) plen 5
                                      [hci0] 8
         Num handles: 1
         Handle: 256
         Count: 1
> ACL Data RX: Handle 256 flags 0x02 dlen 12
                                      [hci0] 16:18:49.598733
       L2CAP: Disconnection Response (0x07) ident 4 len 4
         Destination CID: 65
         Source CID: 64
< HCI Command: Read Clock Offset (0x01|0x001f) plen 2 
           [hci0] 16:18:51.601920
         Handle: 256
> HCI Event: Command Status (0x0f) plen 4
                                      [hci0] 16:18:51.602808
       Read Clock Offset (0x01|0x001f) ncmd 1
         Status: Success (0x00)
< HCI Command: Disconnect (0x01|0x0006) plen 3 
    [hci0] 16:18:51.603069
         Handle: 256
         Reason: Remote User Terminated Connection (0x13)
> HCI Event: Command Status (0x0f) plen 4
                                      [hci0] 16:18:51.603750
       Disconnect (0x01|0x0006) ncmd 1
         Status: Success (0x00)
> HCI Event: Read Clock Offset Complete (0x1c) plen 5
                                      [hci0] 16:18:51.606847
         Status: Success (0x00)
         Handle: 256
         Clock offset: 0x4568
> HCI Event: Disconnect Complete (0x05) plen 4
                                      [hci0] 16:18:51.687885
         Status: Success (0x00)
         Handle: 256
         Reason: Connection Terminated By Local Host (0x16)
@ Device Disconnected: 00:26:5F:D4:27:72 (0) reason 2
< HCI Command: Write Scan Enable (0x03|0x001a) plen 1 
           [hci0] 16:18:51.701737
         Scan enable: Page Scan (0x02)
> HCI Event: Command Complete (0x0e) plen 4
                                      [hci0] 16:18:51.702749
       Write Scan Enable (0x03|0x001a) ncmd 2
         Status: Success (0x00)
@ Device Removed: 00:26:5F:D4:27:72 (0)
< HCI Command: Write Scan Enable (0x03|0x001a) plen 1 
           [hci0] 16:19:04.771489
         Scan enable: No Scans (0x00)

Sorry, previous message sent early by mistake.

Is it possible that the Disconnect event is the source of the leak?

I will try to coordinate the clocks.

Larry