On ingress, a network device such as a switch assigns to packets
priority based on various criteria. Common options include interpreting
PCP and DSCP fields according to user configuration. When a packet
egresses the switch, a reverse process may rewrite PCP and/or DSCP
values according to packet priority.
The following three functions support a) obtaining a DSCP-to-priority
map or vice versa, and b) finding default-priority entries in APP
The DCB subsystem supports for APP entries a very generous M:N mapping
between priorities and protocol identifiers. Understandably,
several (say) DSCP values can map to the same priority. But this
asymmetry holds the other way around as well--one priority can map to
several DSCP values. For this reason, the following functions operate in
terms of bitmaps, with ones in positions that match some APP entry.
- dcb_ieee_getapp_dscp_prio_mask_map() to compute for a given netdevice
a map of DSCP-to-priority-mask, which gives for each DSCP value a
bitmap of priorities related to that DSCP value by APP, along the
lines of dcb_ieee_getapp_mask().
- dcb_ieee_getapp_prio_dscp_mask_map() similarly to compute for a given
netdevice a map from priorities to a bitmap of DSCPs.
- dcb_ieee_getapp_default_prio_mask() which finds all default-priority
rules for a given port in APP database, and returns a mask of
priorities allowed by these default-priority rules.
Signed-off-by: Petr Machata <email@example.com>
Signed-off-by: Ido Schimmel <firstname.lastname@example.org>
Signed-off-by: David S. Miller <email@example.com>