cxl/port: Fix decoder initialization when nr_targets > interleave_ways

The decoder_populate_targets() helper walks all of the targets in a port
and makes sure they can be looked up in @target_map. Where @target_map
is a lookup table from target position to target id (corresponding to a
cxl_dport instance). However @target_map is only responsible for
conveying the active dport instances as indicated by interleave_ways.

When nr_targets > interleave_ways it results in
decoder_populate_targets() walking off the end of the valid entries in
@target_map. Given target_map is initialized to 0 it results in the
dport lookup failing if position 0 is not mapped to a dport with an id
of 0:

  cxl_port port3: Failed to populate active decoder targets
  cxl_port port3: Failed to add decoder
  cxl_port port3: Failed to add decoder3.0
  cxl_bus_probe: cxl_port port3: probe: -6

This bug also highlights that when the decoder's ->targets[] array is
written in cxl_port_setup_targets() it is missing a hold of the
targets_lock to synchronize against sysfs readers of the target list. A
fix for that is saved for a later patch.

Fixes: a5c258021689 ("cxl/bus: Populate the target list at decoder create")
Cc:  <[email protected]>
Signed-off-by: Huang, Ying <[email protected]>
[djbw: rewrite the changelog, find the Fixes: tag]
Co-developed-by: Dan Williams <[email protected]>
Reviewed-by: Alison Schofield <[email protected]>
Reviewed-by: Dave Jiang <[email protected]>
Signed-off-by: Dan Williams <[email protected]>

0 files changed, 0 insertions, 0 deletions