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Subject[PATCH 4.19 131/276] powerpc/numa: improve control of topology updates
Date
[ Upstream commit 2d4d9b308f8f8dec68f6dbbff18c68ec7c6bd26f ]

When booted with "topology_updates=no", or when "off" is written to
/proc/powerpc/topology_updates, NUMA reassignments are inhibited for
PRRN and VPHN events. However, migration and suspend unconditionally
re-enable reassignments via start_topology_update(). This is
incoherent.

Check the topology_updates_enabled flag in
start/stop_topology_update() so that callers of those APIs need not be
aware of whether reassignments are enabled. This allows the
administrative decision on reassignments to remain in force across
migrations and suspensions.

Signed-off-by: Nathan Lynch <nathanl@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
arch/powerpc/mm/numa.c | 18 ++++++++++++------
1 file changed, 12 insertions(+), 6 deletions(-)

diff --git a/arch/powerpc/mm/numa.c b/arch/powerpc/mm/numa.c
index 10fb43efef508..f473c05e96497 100644
--- a/arch/powerpc/mm/numa.c
+++ b/arch/powerpc/mm/numa.c
@@ -1495,6 +1495,9 @@ int start_topology_update(void)
{
int rc = 0;

+ if (!topology_updates_enabled)
+ return 0;
+
if (firmware_has_feature(FW_FEATURE_PRRN)) {
if (!prrn_enabled) {
prrn_enabled = 1;
@@ -1524,6 +1527,9 @@ int stop_topology_update(void)
{
int rc = 0;

+ if (!topology_updates_enabled)
+ return 0;
+
if (prrn_enabled) {
prrn_enabled = 0;
#ifdef CONFIG_SMP
@@ -1579,11 +1585,13 @@ static ssize_t topology_write(struct file *file, const char __user *buf,

kbuf[read_len] = '\0';

- if (!strncmp(kbuf, "on", 2))
+ if (!strncmp(kbuf, "on", 2)) {
+ topology_updates_enabled = true;
start_topology_update();
- else if (!strncmp(kbuf, "off", 3))
+ } else if (!strncmp(kbuf, "off", 3)) {
stop_topology_update();
- else
+ topology_updates_enabled = false;
+ } else
return -EINVAL;

return count;
@@ -1598,9 +1606,7 @@ static const struct file_operations topology_ops = {

static int topology_update_init(void)
{
- /* Do not poll for changes if disabled at boot */
- if (topology_updates_enabled)
- start_topology_update();
+ start_topology_update();

if (vphn_enabled)
topology_schedule_update();
--
2.20.1


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