Bug 820167 - scanning failure after doing wireless roaming on iwl6205
scanning failure after doing wireless roaming on iwl6205
Product: Red Hat Enterprise Linux 6
Classification: Red Hat
Component: kernel (Show other bugs)
Unspecified Unspecified
urgent Severity urgent
: rc
: ---
Assigned To: Stanislaw Gruszka
Desktop QE
Depends On: 766952 808095 814674
  Show dependency treegraph
Reported: 2012-05-09 06:13 EDT by Stanislaw Gruszka
Modified: 2013-01-10 23:10 EST (History)
6 users (show)

See Also:
Fixed In Version:
Doc Type: Bug Fix
Doc Text:
Story Points: ---
Clone Of: 814674
Last Closed: 2012-05-15 06:17:11 EDT
Type: ---
Regression: ---
Mount Type: ---
Documentation: ---
Verified Versions:
Category: ---
oVirt Team: ---
RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: ---

Attachments (Terms of Use)
test-roam2 (2.56 KB, text/plain)
2012-05-09 06:15 EDT, Stanislaw Gruszka
no flags Details
Everything in one file (1.40 MB, application/x-compressed-tar)
2012-05-09 07:51 EDT, Thorsten Hesemeyer
no flags Details
wpa_supplicant.log files from today and yesterday (14.23 MB, application/x-compressed-tar)
2012-05-09 08:19 EDT, Thorsten Hesemeyer
no flags Details

  None (edit)
Description Stanislaw Gruszka 2012-05-09 06:13:47 EDT
Steps to reproduce:
sudo service NetworkManager stop
sudo killall wpa_supplicant
sudo /usr/sbin/wpa_supplicant -c /etc/wpa_supplicant/wpa_supplicant.conf
-B -u -dddt -i wlan0 -D nl80211 -f /var/log/wpa_supplicant.log

Run roaming testing script.

After a while device is unable to scan, and roaming is not performed, only one AP is visible.

iwlist wlan0 scan
wlan0     Failed to read scan data : Resource temporarily unavailable

Additional info:
This happen on laptop with iwl 6205, problem is not reproducible on laptop with 5100 adapter.
Comment 1 Stanislaw Gruszka 2012-05-09 06:15:43 EDT
Created attachment 583207 [details]

Roaming testing script.
Comment 2 Stanislaw Gruszka 2012-05-09 06:19:35 EDT
Issue is not reproducible on RHEL6.3 beta kernel - Thorsten, is that correct?
Comment 4 Thorsten Hesemeyer 2012-05-09 07:51:06 EDT
Created attachment 583235 [details]
Everything in one file


I've put together in one tgz file:
  test-roam2   ... script used (just to be complete)
  dmesg.txt    ... output of dmesg command
  sosreport*   ... files from sosreport of my T420
  (other)      ... ifconfig -a and some more output
The folder var/log/ contains log files from /var/log/
  dmesg        ... /var/log/dmesg file
  messages     ... /var/log/messages file
  wpa_supplicant.log ... /var/log/wpa_supplicant.log file with timestamps and debugging information
  test-roam.log... /var/log/test-roam.log file written by the script above.

The test-roam.log file contains the following fields:
  #1 number of access points found while scanning 
  #2 Date&Time /human readable,
  #3 Time in seconds since 1970
  #4 Uptime Idle in seconds
  #5 Uptime in seconds
Meant to make it easier to join and find the different time stamps from dmesg, messages and other log files.

Kind regards,
Comment 5 Thorsten Hesemeyer 2012-05-09 07:56:27 EDT

the test-roam.log file gives an overview what happened:
  a) started 05/08/12 08:21:14
  b) after 05/08/12 10:26:42 only and exactly one access point visible
  c) after 05/08/12 21:49:45 no access point visible

I was astonished to see there was no access point left over this morning.
But I guess that is really good for finding the issue.

Kind regards,
Comment 6 Thorsten Hesemeyer 2012-05-09 08:19:50 EDT
Created attachment 583258 [details]
wpa_supplicant.log files from today and yesterday


just noticed, the wpa_supplicant information has been log-rotated. 
Here's the information you probably will like to have:

Kind regards,
Comment 8 Stanislaw Gruszka 2012-05-10 06:44:12 EDT
This problem is fixed on RHEL6.3, but we need to find a patch for RHEL6.2.
Comment 10 Thorsten Hesemeyer 2012-05-10 07:15:02 EDT
Hi Stanislaw,

agreed, tested RHEL63 starting yesterday - issue did not occur:
  RHEL62 - usually occurs after a some minutes or one/two hours
  RHEL63 - does not occur even when roaming more than 24h

Kind regards,
Comment 11 Stanislaw Gruszka 2012-05-15 06:17:11 EDT
This issue is not a bug on RHEL6.2 release, but rather bug in one of my test patches, claiming to fix 814674 (wireless roaming test on raw RHEL6.2 kernel will trigger a crash).

There was a race condition that mark scanning as pending, but do not perform actual scan and scan pending state was never unmarked. New scan request finished with -EBUSY (Resource temporarily unavailable) error. Hence after some time there was no AP visible except currently associated one, since kernel internally time out old APs information.

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