On 3 August 2012 13:22, Frederic Danis <frederic.danis@xxxxxxxxxxxxxxx> wrote: > On 03/08/2012 14:15, Frederic Danis wrote: >> >> Hello, >> >> When I try to disconnect Blue Stereo 200 headset (from mrhandsfree) from >> my PC, if headset was the initiator of the connection, the low level >> (ACL) is not disconnected. >> The device is still visible whith "hcitool con". >> >> This happens with BlueZ 4.98 or from git upstream, and kernel 3.4.6. >> There is no disconnection problem with kernel 3.2. >> >> I also try to revert change "Bluetooth: Fix RFCOMM session reference >> counting issue" (commit cf33e7 in linux-stable.git) from Octavian >> Purdila in kernel 3.4.6. >> With this kernel I do not get disconnection problem. >> >> You can find attached hcidump traces. > > > Make a mistake, this was kernel log for l2cap and rfcomm. > > Find attached hcidump traces. > > Fred > > > -- > Frederic Danis Open Source Technology Center > frederic.danis@xxxxxxxxx Intel Corporation > Hi Fred, IMHO, kernel.org's rfcomm session refcnt is fundamentally broken and is in fact redundant. Search back in the mailing list for my previous proposed fixes. One obvious failure of the rfcomm session refcnt is that the refcnt counter either starts with a value of 0 or 1 depending on which peer initiated the connection request, that is wrong. The initiator direction is not relevant for the session as connect and disconnect are independent events. The refcnt should start with a value of 1 in all cases. I am using a 2-core ARM environment that is under high processor loading. The rfcomm session refcnt caused kernel crashes. I used a 2.6.34 kernel but the latest 3.5-RC1 still has the poor rfcomm code. My solution was to remove the rfcomm session refcnt and to ensure that the freeing of the rfcomm session pointer was propagated through-out the rfcomm core code. Some kernel crashes were due to reuse of the freed rfcomm session pointer. I intend to release a patchset of rfcomm fixes. Therefore, IMHO the fix "Bluetooth: Fix RFCOMM session reference counting issue" (commit cf33e7 in linux-stable.git) from Octavian Purdila in kernel 3.4.6 is in fact not fixing the root cause and introduces a misbehaviour of the refcnt. In our project, we rejected this commit because disconnections failed. Regards, Dean -- Dean Jenkins Embedded Software Engineer Professional Services UK/EMEA MontaVista Software, LLC -- To unsubscribe from this list: send the line "unsubscribe linux-bluetooth" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
