Re: [Bluez-users] multithread / multi process use

[Marcel Holtmann <marcel@holtmann.org>]

Hi Emanuele,

> Using 2 threads or 2 process for reading a name of a 2 remote devices
> at same time reports always the same name.
> Is this a bug or the hci functions in library do not support
> concurrent use ? 
> (using 2.6.19 kernel on FC6 and bluez libs 3.7.1)
> 
> This is a simply way to reproduce this:
> 
> open a 2 shells and issue 2 commands at same time 
> 
> hcitool name <bdaddress of a device close to you> 
> 
> they both report the same name
> 
> here an HCI dump of what's happening
> 
> 2007-01-25 11:15:06.093319 < HCI Command: Remote Name Request (0x01|
> 0x0019) plen 10
>     bdaddr 00:0A:28:DF:2B:D8 mode 2 clkoffset 0x0000 
> 2007-01-25 11:15:06.114456 > HCI Event: Command Status (0x0f) plen 4
>     Remote Name Request (0x01|0x0019) status 0x00 ncmd 1
> 2007-01-25 11:15:06.712794 < HCI Command: Remote Name Request (0x01|
> 0x0019) plen 10 
>     bdaddr 00:17:4B:D3:9F:5B mode 2 clkoffset 0x0000
> 2007-01-25 11:15:06.717442 > HCI Event: Command Status (0x0f) plen 4
>     Remote Name Request (0x01|0x0019) status 0x00 ncmd 0
> 2007-01-25 11:15:07.238429 > HCI Event: Remote Name Req Complete
> (0x07) plen 255
>     status 0x00 bdaddr 00:0A:28:DF:2B:D8 name 'Seleso'
> 2007-01-25 11:15:07.239434 > HCI Event: Command Status (0x0f) plen 4
>     Unknown (0x00|0x0000) status 0x00 ncmd 1 
> 2007-01-25 11:15:10.151342 > HCI Event: Remote Name Req Complete
> (0x07) plen 255
>     status 0x00 bdaddr 00:17:4B:D3:9F:5B name 'Wince'
> 
> the second event with the second name is tracked but never reported
> back to the caller cause the unknown event received. 
> so i see the name 'Seleso' as result on both the shells 
> 
> this is the behaviour if I use the 2 command sequentially they works
> fine.
> 
> hcitool name 00:0A:28:DF:2B:D8
> 
> 2007-01-25 11:19:51.930394 < HCI Command: Remote Name Request (0x01|
> 0x0019) plen 10
>     bdaddr 00:0A:28:DF:2B:D8 mode 2 clkoffset 0x0000
> 2007-01-25 11:19:51.951520 > HCI Event: Command Status (0x0f) plen 4
>     Remote Name Request (0x01|0x0019) status 0x00 ncmd 1 
> 2007-01-25 11:19:52.199514 > HCI Event: Remote Name Req Complete
> (0x07) plen 255
>     status 0x00 bdaddr 00:0A:28:DF:2B:D8 name 'Seleso'
> 
> hcitool name 00:17:4B:D3:9F:5B
> 
> 2007-01-25 11:20:39.520967 < HCI Command: Remote Name Request (0x01|
> 0x0019) plen 10
>     bdaddr 00:17:4B:D3:9F:5B mode 2 clkoffset 0x0000
> 2007-01-25 11:20:39.542195 > HCI Event: Command Status (0x0f) plen 4
>     Remote Name Request (0x01|0x0019) status 0x00 ncmd 1 
> 2007-01-25 11:20:43.358090 > HCI Event: Remote Name Req Complete
> (0x07) plen 255
>     status 0x00 bdaddr 00:17:4B:D3:9F:5B name 'Wince'
> 
> 
> 
> 
> Since I need to use search names and search services (FAX especially)
> on a multi-threaded application i'd like to know if is this possible
> or somewhere there is a issue that prevent this. 

actually this is a known bug and basically not really fixable except
doing a massive rework of the HCI API. You are better off to use the
D-Bus interface to get the remote names. It will automatically take of
this for you and also do caching of the names.

Regards

Marcel



-------------------------------------------------------------------------
Take Surveys. Earn Cash. Influence the Future of IT
Join SourceForge.net's Techsay panel and you'll get the chance to share your
opinions on IT & business topics through brief surveys - and earn cash
http://www.techsay.com/default.php?page=join.php&p=sourceforge&CID=DEVDEV
_______________________________________________
Bluez-users mailing list
Bluez-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/bluez-users