In a system with a single initiator node, and one or more memory-only
'target' nodes, the memory-only node(s) would fail to register their
initiator node correctly. i.e. in sysfs:
# ls /sys/devices/system/node/node0/access0/targets/
node0
Where as the correct behavior should be:
# ls /sys/devices/system/node/node0/access0/targets/
node0 node1
This happened because hmat_register_target_initiators() uses list_sort()
to sort the initiator list, but the sort comparision function
(initiator_cmp()) is overloaded to also set the node mask's bits.
In a system with a single initiator, the list is singular, and list_sort
elides the comparision helper call. Thus the node mask never gets set,
and the subsequent search for the best initiator comes up empty.
Add a new helper to sort the initiator list, and handle the singular
list corner case by setting the node mask for that explicitly.
Reported-by: Chris Piper <chris.d.pi...@intel.com>
Cc: <sta...@vger.kernel.org>
Cc: Rafael J. Wysocki <raf...@kernel.org>
Cc: Liu Shixin <liushix...@huawei.com>
Cc: Dan Williams <dan.j.willi...@intel.com>
Signed-off-by: Vishal Verma <vishal.l.ve...@intel.com>
---
drivers/acpi/numa/hmat.c | 32 ++++++++++++++++++++++++++++++--
1 file changed, 30 insertions(+), 2 deletions(-)
diff --git a/drivers/acpi/numa/hmat.c b/drivers/acpi/numa/hmat.c
index 144a84f429ed..cd20b0e9cdfa 100644
--- a/drivers/acpi/numa/hmat.c
+++ b/drivers/acpi/numa/hmat.c
@@ -573,6 +573,30 @@ static int initiator_cmp(void *priv, const struct
list_head *a,
return ia->processor_pxm - ib->processor_pxm;
}
+static int initiators_to_nodemask(unsigned long *p_nodes)
+{
+ /*
+ * list_sort doesn't call @cmp (initiator_cmp) for 0 or 1 sized lists.
+ * For a single-initiator system with other memory-only nodes, this
+ * means an empty p_nodes mask, since that is set by initiator_cmp().
+ * Special case the singular list, and make sure the node mask gets set
+ * appropriately.
+ */
+ if (list_empty(&initiators))
+ return -ENXIO;
+
+ if (list_is_singular(&initiators)) {
+ struct memory_initiator *initiator = list_first_entry(
+ &initiators, struct memory_initiator, node);
+
+ set_bit(initiator->processor_pxm, p_nodes);
+ return 0;
+ }
+
+ list_sort(p_nodes, &initiators, initiator_cmp);
+ return 0;
+}
+
static void hmat_register_target_initiators(struct memory_target *target)
{
static DECLARE_BITMAP(p_nodes, MAX_NUMNODES);
@@ -609,7 +633,9 @@ static void hmat_register_target_initiators(struct
memory_target *target)
* initiators.
*/
bitmap_zero(p_nodes, MAX_NUMNODES);
- list_sort(p_nodes, &initiators, initiator_cmp);
+ if (initiators_to_nodemask(p_nodes) < 0)
+ return;
+
if (!access0done) {
for (i = WRITE_LATENCY; i <= READ_BANDWIDTH; i++) {
loc = localities_types[i];
@@ -643,7 +669,9 @@ static void hmat_register_target_initiators(struct
memory_target *target)
/* Access 1 ignores Generic Initiators */
bitmap_zero(p_nodes, MAX_NUMNODES);
- list_sort(p_nodes, &initiators, initiator_cmp);
+ if (initiators_to_nodemask(p_nodes) < 0)
+ return;
+
for (i = WRITE_LATENCY; i <= READ_BANDWIDTH; i++) {
loc = localities_types[i];
if (!loc)
--
2.38.1
