[PATCH v4 3/4] arch_topology: Reset SMT state when topology is unavailable

[Sudeep Holla <sudeep.holla@kernel.org>]

If DT has no CPU information or cpu-map, parsing succeeds without
notifying the SMT framework. A later topology validation failure can
discard parsed data while leaving the SMT thread count set by
parse_socket().

Reset the count to one on these paths so the SMT framework matches
the topology that remains available.

Reported-by: Sashiko <sashiko-bot@kernel.org>
Closes: https://sashiko.dev/#/bug/linux-486a8656-d962-4966-8d90-bbb2ce276147
Fixes: 5deb9c789ae4 ("arch_topology: Support SMT control for OF based system")
Signed-off-by: Sudeep Holla <sudeep.holla@kernel.org>
---
 drivers/base/arch_topology.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/base/arch_topology.c b/drivers/base/arch_topology.c
index eea4c4257d08..c439fc91270d 100644
--- a/drivers/base/arch_topology.c
+++ b/drivers/base/arch_topology.c
@@ -662,6 +662,7 @@ static int __init parse_dt_topology(void)
 
 	if (!cn) {
 		pr_err("No CPU information found in DT\n");
+		cpu_smt_set_num_threads(1, 1);
 		return 0;
 	}
 
@@ -672,8 +673,10 @@ static int __init parse_dt_topology(void)
 	struct device_node *map __free(device_node) =
 		of_get_child_by_name(cn, "cpu-map");
 
-	if (!map)
+	if (!map) {
+		cpu_smt_set_num_threads(1, 1);
 		return ret;
+	}
 
 	ret = parse_socket(map);
 	if (ret != 0)
@@ -951,6 +954,7 @@ void __init init_cpu_topology(void)
 		 * arch-specific early cache level detection a chance to run.
 		 */
 		reset_cpu_topology();
+		cpu_smt_set_num_threads(1, 1);
 	}
 
 	for_each_possible_cpu(cpu) {
-- 
2.43.0