misc/170433: [ath] TX hang after a stuck beacon message with active traffic

[Adrian Chadd]

>Number:         170433
>Category:       misc
>Synopsis:       [ath] TX hang after a stuck beacon message with active traffic
>Confidential:   no
>Severity:       non-critical
>Priority:       low
>Responsible:    freebsd-bugs
>State:          open
>Quarter:        
>Keywords:       
>Date-Required:
>Class:          sw-bug
>Submitter-Id:   current-users
>Arrival-Date:   Tue Aug 07 00:40:03 UTC 2012
>Closed-Date:
>Last-Modified:
>Originator:     Adrian Chadd
>Release:        9.0-STABLE, HEAD net80211/ath
>Organization:
>Environment:
>Description:
When doing iperf tests to a FreeBSD AP in 2.4GHz, a stuck beacon event would result in traffic stalls.

This can be flushed by one or more "sysctl dev.ath.X.forcebstuck=1" commands.

IT didn't show up in 5GHz mode because I never saw a stuck beacon issue.
>How-To-Repeat:

>Fix:

The problem is in ath_legacy_tx_dma_restart(). It was initialising the wrong link pointer and so the TX queue would end up with incorrect link information.

>Release-Note:
>Audit-Trail:
>Unformatted: