From: Huang Ying <ying.huang@xxxxxxxxx>
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 conveyed 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: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: "Huang, Ying" <ying.huang@xxxxxxxxx>
[djbw: rewrite the changelog, find the Fixes: tag]
Co-developed-by: Dan Williams <dan.j.williams@xxxxxxxxx>
Signed-off-by: Dan Williams <dan.j.williams@xxxxxxxxx>
---
drivers/cxl/core/port.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/cxl/core/port.c b/drivers/cxl/core/port.c
index b7c93bb18f6e..57495cdc181f 100644
--- a/drivers/cxl/core/port.c
+++ b/drivers/cxl/core/port.c
@@ -1644,7 +1644,7 @@ static int decoder_populate_targets(struct cxl_switch_decoder *cxlsd,
return -EINVAL;
write_seqlock(&cxlsd->target_lock);
- for (i = 0; i < cxlsd->nr_targets; i++) {
+ for (i = 0; i < cxlsd->cxld.interleave_ways; i++) {
struct cxl_dport *dport = find_dport(port, target_map[i]);
if (!dport) {
