On 05/08/2013 10:58 AM, Johannes Berg wrote:
On Wed, 2013-05-08 at 09:18 -0700, Ben Greear wrote:
Ok, I reproduced this with yet more debugging printouts in the kernel.
The symptom is this:
The sme_state is SME_CONNECTED, so it bails out below before sending the
'connected' message to user-space.
Is your system being really really really slow and/or are threads
getting pre-empted a lot? This maybe seem like a bit of a stretch, but
it seems possible that this happens:
ieee80211_sta_rx_queued_mgmt() is running, possibly on one CPU, and is
somewhere between printing "associated" and calling
cfg80211_send_rx_assoc() (or in the call already, before taking the lock
though.)
Then your interface is set down at the same time, possibly on a
different CPU. Here's where the scenario gets stretched, clearly your
interface is getting set down over a minute later, I don't see how you
could have stalled the other thread for that long.
But if you did, then that thread is still processing things while the
interface is going down, cfg80211 didn't know anything about the
association having completed so it won't have disconnected, etc.
So far, I haven't found any other scenario, nor a solution.
It is not that slow or overloaded (at least most of the time,
and in particular, I only had 20 virtual stations up on this system
not doing much traffic...it easily handles 100's of stations).
And, once it gets in this state..it stays there (overnight,
with my app resetting the port (via 'ip link set down' and
poking at wpa_supplicant) every minute or so in this case.
I was wondering..in the cfg80211_mlme_down method (or perhaps
some place similar), should we force sme state to IDLE
with a big WARN_ON_ONCE or similar.
That way, if it does get stuck somehow, we can recover by
downing the interface and bringing it back up?
For what it's worth, I don't recall ever seeing this problem
in 5.7, but it's way to rare to be able to bisect...
Thanks,
Ben
johannes
--
Ben Greear <greearb@xxxxxxxxxxxxxxx>
Candela Technologies Inc http://www.candelatech.com
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