[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-ID: <27ac48c0-b19c-4104-8ec9-08232e3f42f6@fiberby.net>
Date: Fri, 12 Apr 2024 09:01:15 +0000
From: Asbjørn Sloth Tønnesen <ast@...erby.net>
To: Suman Ghosh <sumang@...vell.com>,
"netdev@...r.kernel.org" <netdev@...r.kernel.org>
Cc: "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
"David S. Miller" <davem@...emloft.net>, Eric Dumazet <edumazet@...gle.com>,
Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>,
Sunil Kovvuri Goutham <sgoutham@...vell.com>,
Geethasowjanya Akula <gakula@...vell.com>,
Subbaraya Sundeep Bhatta <sbhatta@...vell.com>,
Hariprasad Kelam <hkelam@...vell.com>
Subject: Re: [PATCH net] octeontx2-pf: fix FLOW_DIS_IS_FRAGMENT implementation
Hi Suman,
On 4/12/24 5:34 AM, Suman Ghosh wrote:
>> if (match.mask->flags & FLOW_DIS_IS_FRAGMENT) {
>> + val = match.key->flags & FLOW_DIS_IS_FRAGMENT;
>> if (ntohs(flow_spec->etype) == ETH_P_IP) {
>> - flow_spec->ip_flag = IPV4_FLAG_MORE;
>> + flow_spec->ip_flag = val ? IPV4_FLAG_MORE : 0;
> [Suman] Do we need this? If user provide the command "tc filter add .... ip_flags nofrags" then the above if check should not be hit right? If we are inside the check then we always want to set IPV4_FLAG_MORE right?
In iproute2, the "frag"/"nofrag" is parsed in flower_parse_matching_flags(),
it sets TCA_FLOWER_KEY_FLAGS_IS_FRAGMENT in TCA_FLOWER_KEY_FLAGS and
TCA_FLOWER_KEY_FLAGS_MASK.
Back in the kernel, in fl_set_key_flags() (net/sched/cls_flower.c) then,
directly translates TCA_FLOWER_KEY_FLAGS_IS_FRAGMENT into FLOW_DIS_IS_FRAGMENT,
while only setting the key bit, if the mask bit is being set.
There are therefore 3 possible cases:
- `tc flower ...` (no ip_flags frag or nofrag)
(match.key->flags & FLOW_DIS_FIRST_FRAG) is false
(match.mask->flags & FLOW_DIS_FIRST_FRAG) is false
- `tc flower ... ip_flags nofrag`
(match.key->flags & FLOW_DIS_FIRST_FRAG) is false
(match.mask->flags & FLOW_DIS_FIRST_FRAG) is true
- `tc flower ... ip_flags frag`
(match.key->flags & FLOW_DIS_FIRST_FRAG) is true
(match.mask->flags & FLOW_DIS_FIRST_FRAG) is true
The `nofrag` case will still have the mask bit set, and hence pass the entry condition.
>> flow_mask->ip_flag = IPV4_FLAG_MORE;
Yes, you should always set IPV4_FLAG_MORE in flow_mask, but not always in flow_spec.
--
Best regards
Asbjørn Sloth Tønnesen
Network Engineer
Fiberby - AS42541
Powered by blists - more mailing lists