Re: [PATCH] inet_diag: fix reporting cgroup classid and fallback to priority

[David Miller]

From: Konstantin Khlebnikov <khlebnikov@xxxxxxxxxxxxxx>
Date: Sat, 09 Feb 2019 13:35:52 +0300

> Field idiag_ext in struct inet_diag_req_v2 used as bitmap of requested
> extensions has only 8 bits. Thus extensions starting from DCTCPINFO
> cannot be requested directly. Some of them included into response
> unconditionally or hook into some of lower 8 bits.
> 
> Extension INET_DIAG_CLASS_ID has not way to request from the beginning.
> 
> This patch bundle it with INET_DIAG_TCLASS (ipv6 tos), fixes space
> reservation, and documents behavior for other extensions.
> 
> Also this patch adds fallback to reporting socket priority. This filed
> is more widely used for traffic classification because ipv4 sockets
> automatically maps TOS to priority and default qdisc pfifo_fast knows
> about that. But priority could be changed via setsockopt SO_PRIORITY so
> INET_DIAG_TOS isn't enough for predicting class.
> 
> Also cgroup2 obsoletes net_cls classid (it always zero), but we cannot
> reuse this field for reporting cgroup2 id because it is 64-bit (ino+gen).
> 
> So, after this patch INET_DIAG_CLASS_ID will report socket priority
> for most common setup when net_cls isn't set and/or cgroup2 in use.
> 
> Signed-off-by: Konstantin Khlebnikov <khlebnikov@xxxxxxxxxxxxxx>
> Fixes: 0888e372c37f ("net: inet: diag: expose sockets cgroup classid")

Applied, and queued up for -stable.

Please always put the Fixes: tag first in the list of tags.  I fixed
it up for you this time.

Thanks.