diff options
| author | Vladimir Oltean <vladimir.oltean@nxp.com> | 2023-04-11 21:01:55 +0300 |
|---|---|---|
| committer | Jakub Kicinski <kuba@kernel.org> | 2023-04-13 22:22:10 -0700 |
| commit | a721c3e54b80e45cd9202e7fca29ef018bed9069 (patch) | |
| tree | b9c097e81750a251d194e8bbfc2e1da337d04f8a /include/uapi | |
| parent | f62af20bed2d9e824f51cfc97ff01bc261f40e58 (diff) | |
net/sched: taprio: allow per-TC user input of FP adminStatus
This is a duplication of the FP adminStatus logic introduced for
tc-mqprio. Offloading is done through the tc_mqprio_qopt_offload
structure embedded within tc_taprio_qopt_offload. So practically, if a
device driver is written to treat the mqprio portion of taprio just like
standalone mqprio, it gets unified handling of frame preemption.
I would have reused more code with taprio, but this is mostly netlink
attribute parsing, which is hard to transform into generic code without
having something that stinks as a result. We have the same variables
with the same semantics, just different nlattr type values
(TCA_MQPRIO_TC_ENTRY=5 vs TCA_TAPRIO_ATTR_TC_ENTRY=12;
TCA_MQPRIO_TC_ENTRY_FP=2 vs TCA_TAPRIO_TC_ENTRY_FP=3, etc) and
consequently, different policies for the nest.
Every time nla_parse_nested() is called, an on-stack table "tb" of
nlattr pointers is allocated statically, up to the maximum understood
nlattr type. That array size is hardcoded as a constant, but when
transforming this into a common parsing function, it would become either
a VLA (which the Linux kernel rightfully doesn't like) or a call to the
allocator.
Having FP adminStatus in tc-taprio can be seen as addressing the 802.1Q
Annex S.3 "Scheduling and preemption used in combination, no HOLD/RELEASE"
and S.4 "Scheduling and preemption used in combination with HOLD/RELEASE"
use cases. HOLD and RELEASE events are emitted towards the underlying
MAC Merge layer when the schedule hits a Set-And-Hold-MAC or a
Set-And-Release-MAC gate operation. So within the tc-taprio UAPI space,
one can distinguish between the 2 use cases by choosing whether to use
the TC_TAPRIO_CMD_SET_AND_HOLD and TC_TAPRIO_CMD_SET_AND_RELEASE gate
operations within the schedule, or just TC_TAPRIO_CMD_SET_GATES.
A small part of the change is dedicated to refactoring the max_sdu
nlattr parsing to put all logic under the "if" that tests for presence
of that nlattr.
Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Reviewed-by: Ferenc Fejes <fejes@inf.elte.hu>
Reviewed-by: Simon Horman <simon.horman@corigine.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Diffstat (limited to 'include/uapi')
| -rw-r--r-- | include/uapi/linux/pkt_sched.h | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/include/uapi/linux/pkt_sched.h b/include/uapi/linux/pkt_sched.h index b8d29be91b62..51a7addc56c6 100644 --- a/include/uapi/linux/pkt_sched.h +++ b/include/uapi/linux/pkt_sched.h @@ -1252,6 +1252,7 @@ enum { TCA_TAPRIO_TC_ENTRY_UNSPEC, TCA_TAPRIO_TC_ENTRY_INDEX, /* u32 */ TCA_TAPRIO_TC_ENTRY_MAX_SDU, /* u32 */ + TCA_TAPRIO_TC_ENTRY_FP, /* u32 */ /* add new constants above here */ __TCA_TAPRIO_TC_ENTRY_CNT, |