Re: [PATCH] net_sched: gred: Fix oops in gred_dump() in WRED mode

[David Miller <davem@davemloft.net>]

From: David Ward <david.ward@ll.mit.edu>
Date: Sun, 15 Apr 2012 18:31:45 -0400

> A parameter set exists for WRED mode, called wred_set, to hold the same
> values for qavg and qidlestart across all VQs. The WRED mode values had
> been previously held in the VQ for the default DP. After these values
> were moved to wred_set, the VQ for the default DP was no longer created
> automatically (so that it could be omitted on purpose, to have packets
> in the default DP enqueued directly to the device without using RED).
> 
> However, gred_dump() was overlooked during that change; in WRED mode it
> still reads qavg/qidlestart from the VQ for the default DP, which might
> not even exist. As a result, this command sequence will cause an oops:
> 
> tc qdisc add dev $DEV handle $HANDLE parent $PARENT gred setup \
>     DPs 3 default 2 grio
> tc qdisc change dev $DEV handle $HANDLE gred DP 0 prio 8 $RED_OPTIONS
> tc qdisc change dev $DEV handle $HANDLE gred DP 1 prio 8 $RED_OPTIONS
> 
> This fixes gred_dump() in WRED mode to use the values held in wred_set.
> 
> Signed-off-by: David Ward <david.ward@ll.mit.edu>

Applied and queued up for -stable, thanks David.