[PATCH] powerpc/pseries: Hold reference and fix refcount leak bugs

[PATCH] powerpc/pseries: Hold reference and fix refcount leak bugs

[Liang He]

In pseries_cpuhp_cache_use_count() and pseries_cpuhp_detach_nodes(),
we need carefully hold the reference returned by
of_find_next_cache_node() and use it to call of_node_put() to keep
refcount balance.

Signed-off-by: Liang He <windhl@126.com>
---
 arch/powerpc/platforms/pseries/hotplug-cpu.c | 15 +++++++++++----
 1 file changed, 11 insertions(+), 4 deletions(-)

diff --git a/arch/powerpc/platforms/pseries/hotplug-cpu.c b/arch/powerpc/platforms/pseries/hotplug-cpu.c
index 0f8cd8b06432..e0a7ac5db15d 100644
--- a/arch/powerpc/platforms/pseries/hotplug-cpu.c
+++ b/arch/powerpc/platforms/pseries/hotplug-cpu.c
@@ -619,17 +619,21 @@ static ssize_t dlpar_cpu_add(u32 drc_index)
 static unsigned int pseries_cpuhp_cache_use_count(const struct device_node *cachedn)
 {
 	unsigned int use_count = 0;
-	struct device_node *dn;
+	struct device_node *dn, *tn;
 
 	WARN_ON(!of_node_is_type(cachedn, "cache"));
 
 	for_each_of_cpu_node(dn) {
-		if (of_find_next_cache_node(dn) == cachedn)
+		tn = of_find_next_cache_node(dn);
+		of_node_put(tn);
+		if (tn == cachedn)
 			use_count++;
 	}
 
 	for_each_node_by_type(dn, "cache") {
-		if (of_find_next_cache_node(dn) == cachedn)
+		tn = of_find_next_cache_node(dn);
+		of_node_put(tn);
+		if (tn == cachedn)
 			use_count++;
 	}
 
@@ -649,10 +653,13 @@ static int pseries_cpuhp_detach_nodes(struct device_node *cpudn)
 
 	dn = cpudn;
 	while ((dn = of_find_next_cache_node(dn))) {
-		if (pseries_cpuhp_cache_use_count(dn) > 1)
+		if (pseries_cpuhp_cache_use_count(dn) > 1) {
+			of_node_put(dn);
 			break;
+		}
 
 		ret = of_changeset_detach_node(&cs, dn);
+		of_node_put(dn);
 		if (ret)
 			goto out;
 	}
-- 
2.25.1

Re: [PATCH] powerpc/pseries: Hold reference and fix refcount leak bugs

[Michael Ellerman]

On Tue, 21 Jun 2022 19:17:01 +0800, Liang He wrote:
> In pseries_cpuhp_cache_use_count() and pseries_cpuhp_detach_nodes(),
> we need carefully hold the reference returned by
> of_find_next_cache_node() and use it to call of_node_put() to keep
> refcount balance.
> 
> 

Applied to powerpc/next.

[1/1] powerpc/pseries: Hold reference and fix refcount leak bugs
      https://git.kernel.org/powerpc/c/6ec4836fa15a0ff02e3a382ad6b1920c728a8c95

cheers