Re: [PATCH v2 BlueZ] hid2hci: Fix udev rules for linux-4.14+

[Dag B]

On 05.12.2018 16:40, Ville SyrjÃlà wrote:
> On Wed, Dec 05, 2018 at 08:06:21AM +0100, Greg Kroah-Hartman wrote:
> > On Tue, Dec 04, 2018 at 10:41:17PM +0200, Ville Syrjala wrote:
> > > From: Ville SyrjÃlà <ville.syrjala@xxxxxxxxxxxxxxx>
> > >
> > > Since commit 1455cf8dbfd0 ("driver core: emit uevents when
> > > device is bound to a driver") the kernel started emitting
> > > "bind" and "unbind" uevents which confuse the hid2hci
> > > udev rules.
> > >
> > > The symptoms on an affected machine (Dell E5400 in my case)
> > > include bluetooth devices not appearing and udev hogging
> > > the cpu as it's busy processing a constant stream of these
> > > "bind"+"unbind" uevents.
> > What is causing a "stream" of bind and unbind events?  This only happens
> > when a device is attached to a driver or removed from a driver, which is
> > caused by something else happening.
> Not sure if it's just due to this thing causing devices to
> appear/disappear during bind/unbind events or what.
>
> > This should not be a normal
> > occurance, unless something odd is happening to your hardware?
> It's not specific to my hardware. Lot's of people are affected.
> See eg.
> https://bugs.launchpad.net/ubuntu/+source/systemd/+bug/1759836
>
> Acutally looking through that bug it seems someone else noticed
> hid2hci failing lot in the logs. So maybe it's just that we already
> switched the mode during "add", and then we try to redo the same
> thing during "bind" which fails, and that then causes and unbind?
> Dunno, udev is beyond me.
There is another bluetooth scenario where a cpu core peaks at 100%.
This is when a bluetooth keyboard goes out to lunch/suspends/disappears.
No idea if this is related to the original issue, asking forgiveness if 
it is not.
I have found it challenging to attract any attention to the problem, 
despite it not being an entirely new or uncommon occurence.

Google the following terms: bluetooth keyboard bluetoothd linux 100% cpu



By chance, I discovered a supposed fix for this on github today. I have 
not had the chance to test it (or if it even applies) yet:

https://github.com/peak3d/bluez/commit/9cc3c1afd793e40b1a0cdc4a13e08b5e2575759e

Could someone please shine a light on the sanity of this patch?



Dag B