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: <[email protected]>
Cc: Rafael J. Wysocki <[email protected]>
Cc: Liu Shixin <[email protected]>
Cc: Dan Williams <[email protected]>
Cc: Kirill A. Shutemov <[email protected]>
Reported-by: Chris Piper <[email protected]>
Signed-off-by: Vishal Verma <[email protected]>
---
drivers/acpi/numa/hmat.c | 26 ++++++++++++++++++++------
1 file changed, 20 insertions(+), 6 deletions(-)
diff --git a/drivers/acpi/numa/hmat.c b/drivers/acpi/numa/hmat.c
index 144a84f429ed..6cceca64a6bc 100644
--- a/drivers/acpi/numa/hmat.c
+++ b/drivers/acpi/numa/hmat.c
@@ -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)
--
2.38.1
On Wed, Nov 16, 2022 at 04:37:37PM -0700, Vishal Verma wrote:
> 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: <[email protected]>
> Cc: Rafael J. Wysocki <[email protected]>
> Cc: Liu Shixin <[email protected]>
> Cc: Dan Williams <[email protected]>
> Cc: Kirill A. Shutemov <[email protected]>
> Reported-by: Chris Piper <[email protected]>
> Signed-off-by: Vishal Verma <[email protected]>
Acked-by: Kirill A. Shutemov <[email protected]>
--
Kiryl Shutsemau / Kirill A. Shutemov
On 11/17/2022 12:37 AM, Vishal Verma wrote:
> 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: <[email protected]>
> Cc: Rafael J. Wysocki <[email protected]>
> Cc: Liu Shixin <[email protected]>
> Cc: Dan Williams <[email protected]>
> Cc: Kirill A. Shutemov <[email protected]>
> Reported-by: Chris Piper <[email protected]>
> Signed-off-by: Vishal Verma <[email protected]>
Acked-by: Rafael J. Wysocki <[email protected]>
> ---
> drivers/acpi/numa/hmat.c | 26 ++++++++++++++++++++------
> 1 file changed, 20 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/acpi/numa/hmat.c b/drivers/acpi/numa/hmat.c
> index 144a84f429ed..6cceca64a6bc 100644
> --- a/drivers/acpi/numa/hmat.c
> +++ b/drivers/acpi/numa/hmat.c
> @@ -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)
>