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Bug 498719

Summary: [patch] mac80211: nullfunc and hidden SSID fixes
Product: Red Hat Enterprise Linux 5 Reporter: Dan Williams <dcbw>
Component: kernelAssignee: John W. Linville <linville>
Status: CLOSED ERRATA QA Contact: Red Hat Kernel QE team <kernel-qe>
Severity: medium Docs Contact:
Priority: low    
Version: 5.4CC: aleksey, caillon, dzickus, walicki
Target Milestone: rc   
Target Release: ---   
Hardware: All   
OS: Linux   
Whiteboard:
Fixed In Version: Doc Type: Bug Fix
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Clone Of: Environment:
Last Closed: 2009-09-02 08:59:37 UTC Type: ---
Regression: --- Mount Type: ---
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Verified Versions: Category: ---
oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
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Description Flags
scanning fixes for mac80211 none

Description Dan Williams 2009-05-02 14:13:37 UTC 
Created attachment 342178 [details]
scanning fixes for mac80211

Fix #1:

When returning from a scan, the stack tried to probe the last-scanned SSID, which is completely wrong, and may not even have existed.  It's supposed to be probing the previously associated SSID instead.  This caused the stack to periodically disconnect from hidden-SSID access points becuase the hidden SSID doesn't show up in the scan list, and the probe-request to that SSID is required to determine if its still present.

Fix #2:

The mac80211 stack sends null packets when beginning a scan to alert the AP that it should buffer frames for the STA while the STA is scanning.  However, the TX path of mac80211 would simply drop these frames on the floor, causing the AP not to buffer frames, and leading to deauthentications due to excessive retries on the AP.

This leads to choppy or broken streaming video, intermittent connection failures when using NetworkManager due to the extra steps required to reauthenticate to the AP when it has dropped you due to excessive retries, etc.

This patch came out of the debugging sessions I've been having with a large customer of the past 3 weeks.  See bug #493745 & IT #283289 for the details.
Comment 1 John W. Linville 2009-05-05 14:34:28 UTC 
Test kernels w/ the attached patch are available here:

   http://people.redhat.com/linville/kernels/rhel5/

Please give them a try and post the results...thanks!
Comment 2 RHEL Program Management 2009-05-05 14:48:55 UTC 
This request was evaluated by Red Hat Product Management for inclusion in a Red
Hat Enterprise Linux maintenance release.  Product Management has requested
further review of this request by Red Hat Engineering, for potential
inclusion in a Red Hat Enterprise Linux Update release for currently deployed
products.  This request is not yet committed for inclusion in an Update
release.
Comment 4 John Walicki 2009-05-06 01:25:13 UTC 
Dan - Thanks for your support on these patches.  Huge improvement in wireless stability. 

I'll post in the IssueTracker ticket to advocate for inclusion in RHEL 5.4
Comment 5 Don Zickus 2009-05-12 17:41:37 UTC 
in kernel-2.6.18-146.el5
You can download this test kernel from http://people.redhat.com/dzickus/el5

Please do NOT transition this bugzilla state to VERIFIED until our QE team
has sent specific instructions indicating when to do so.  However feel free
to provide a comment indicating that this fix has been verified.
Comment 8 errata-xmlrpc 2009-09-02 08:59:37 UTC 
An advisory has been issued which should help the problem
described in this bug report. This report is therefore being
closed with a resolution of ERRATA. For more information
on therefore solution and/or where to find the updated files,
please follow the link below. You may reopen this bug report
if the solution does not work for you.

http://rhn.redhat.com/errata/RHSA-2009-1243.html