Commit 48d41809 authored by Vishal Verma's avatar Vishal Verma Committed by Dan Williams
Browse files

ACPI: HMAT: Fix initiator registration for single-initiator systems 



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 consume the sorted initiator list, and generate the
nodemask, decoupling it from the overloaded initiator_cmp() comparision
callback. This prevents the singular list corner case naturally, and
makes the code easier to follow as well.

Cc: <stable@vger.kernel.org>
Cc: Rafael J. Wysocki <rafael@kernel.org>
Cc: Liu Shixin <liushixin2@huawei.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Reported-by: default avatarChris Piper <chris.d.piper@intel.com>
Signed-off-by: default avatarVishal Verma <vishal.l.verma@intel.com>
Acked-by: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: default avatarKirill A. Shutemov <kirill.shutemov@linux.intel.com>
Link: https://lore.kernel.org/r/20221116-acpi_hmat_fix-v2-2-3712569be691@intel.com


Signed-off-by: default avatarDan Williams <dan.j.williams@intel.com>
parent 14f16d47

drivers/acpi/numa/hmat.c

+20 −6
Original line number Diff line number Diff line
@@ -562,17 +562,26 @@ static int initiator_cmp(void *priv, const struct list_head *a, 
{

	struct memory_initiator *ia;

	struct memory_initiator *ib;

	unsigned long *p_nodes = priv;



	ia = list_entry(a, struct memory_initiator, node);

	ib = list_entry(b, struct memory_initiator, node);



	set_bit(ia->processor_pxm, p_nodes);

	set_bit(ib->processor_pxm, p_nodes);



	return ia->processor_pxm - ib->processor_pxm;

}



static int initiators_to_nodemask(unsigned long *p_nodes)

{

	struct memory_initiator *initiator;



	if (list_empty(&initiators))

		return -ENXIO;



	list_for_each_entry(initiator, &initiators, node)

		set_bit(initiator->processor_pxm, p_nodes);



	return 0;

}



static void hmat_register_target_initiators(struct memory_target *target)

{

	static DECLARE_BITMAP(p_nodes, MAX_NUMNODES);
@@ -609,7 +618,10 @@ static void hmat_register_target_initiators(struct memory_target *target) 
	 * initiators.

	 */

	bitmap_zero(p_nodes, MAX_NUMNODES);

	list_sort(p_nodes, &initiators, initiator_cmp);

	list_sort(NULL, &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 +655,9 @@ 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)