Re: [PATCH stable] net: sch_generic: fix the missing new qdisc assignment bug

[Brian Norris]

On Tue, Nov 03, 2020 at 11:25:38AM +0800, Yunsheng Lin wrote:
> commit 2fb541c862c9 ("net: sch_generic: aviod concurrent reset and enqueue op for lockless qdisc")
> 
> When the above upstream commit is backported to stable kernel,
> one assignment is missing, which causes two problems reported
> by Joakim and Vishwanath, see [1] and [2].
> 
> So add the assignment back to fix it.
> 
> 1. https://www.spinics.net/lists/netdev/msg693916.html
> 2. https://www.spinics.net/lists/netdev/msg695131.html
> 
> Fixes: 749cc0b0c7f3 ("net: sch_generic: aviod concurrent reset and enqueue op for lockless qdisc")
> Signed-off-by: Yunsheng Lin <linyunsheng@xxxxxxxxxx>

For whatever it's worth, we've seen similar problems (particularly,
ENOBUFS on AF_PACKET sockets) and have tested this fix on 4.19.y (we're
also queueing it up on our 5.4.y branch, but haven't tested it as much):

Tested-by: Brian Norris <briannorris@xxxxxxxxxxxx>

Thanks!