21225873be
For ENETC hardware, the TCs are numbered from 0 to N-1, where N
is the number of TCs. Numerically higher TC has higher priority.
It's obvious that the highest priority TC index should be N-1 and
the 2nd highest priority TC index should be N-2.
However, the previous logic uses netdev_get_prio_tc_map() to get
the indexes of highest priority and 2nd highest priority TCs, it
does not make sense and is incorrect to give a "tc" argument to
netdev_get_prio_tc_map(). So the driver may get the wrong indexes
of the two highest priotiry TCs which would lead to failed to set
the CBS for the two highest priotiry TCs.
e.g.
$ tc qdisc add dev eno0 parent root handle 100: mqprio num_tc 6 \
map 0 0 1 1 2 3 4 5 queues 1@0 1@1 1@2 1@3 2@4 2@6 hw 1
$ tc qdisc replace dev eno0 parent 100:6 cbs idleslope 100000 \
sendslope -900000 hicredit 12 locredit -113 offload 1
$ Error: Specified device failed to setup cbs hardware offload.
^^^^^
In this example, the previous logic deems the indexes of the two
highest priotiry TCs should be 3 and 2. Actually, the indexes are
5 and 4, because the number of TCs is 6. So it would be failed to
configure the CBS for the two highest priority TCs.
Fixes: c431047c4efe ("enetc: add support Credit Based Shaper(CBS) for hardware offload")
Signed-off-by: Wei Fang <wei.fang@nxp.com>
Reviewed-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Reviewed-by: Maciej Fijalkowski <maciej.fijalkowski@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.