[PATCH] powercap: intel_rapl: Optimize rp->domains memory allocation

[xiongxin <xiongxin@xxxxxxxxxx>]

In the memory allocation of rp->domains in rapl_detect_domains(), there
is an additional memory of struct rapl_domain allocated to prevent the
pointer out of bounds called later.

Optimize the code here to save sizeof(struct rapl_domain) bytes of
memory.

Test in Intel NUC (i5-1135G7).

Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: xiongxin <xiongxin@xxxxxxxxxx>
Tested-by: xiongxin <xiongxin@xxxxxxxxxx>
---
 drivers/powercap/intel_rapl_common.c | 15 ++++++++-------
 1 file changed, 8 insertions(+), 7 deletions(-)

diff --git a/drivers/powercap/intel_rapl_common.c b/drivers/powercap/intel_rapl_common.c
index 8970c7b80884..f8971282498a 100644
--- a/drivers/powercap/intel_rapl_common.c
+++ b/drivers/powercap/intel_rapl_common.c
@@ -1171,13 +1171,14 @@ static int rapl_package_register_powercap(struct rapl_package *rp)
 {
 	struct rapl_domain *rd;
 	struct powercap_zone *power_zone = NULL;
-	int nr_pl, ret;
+	int nr_pl, ret, i;
 
 	/* Update the domain data of the new package */
 	rapl_update_domain_data(rp);
 
 	/* first we register package domain as the parent zone */
-	for (rd = rp->domains; rd < rp->domains + rp->nr_domains; rd++) {
+	for (i = 0; i < rp->nr_domains; i++) {
+		rd = &rp->domains[i];
 		if (rd->id == RAPL_DOMAIN_PACKAGE) {
 			nr_pl = find_nr_power_limit(rd);
 			pr_debug("register package domain %s\n", rp->name);
@@ -1201,8 +1202,9 @@ static int rapl_package_register_powercap(struct rapl_package *rp)
 		return -ENODEV;
 	}
 	/* now register domains as children of the socket/package */
-	for (rd = rp->domains; rd < rp->domains + rp->nr_domains; rd++) {
+	for (i = 0; i < rp->nr_domains; i++) {
 		struct powercap_zone *parent = rp->power_zone;
+		rd = &rp->domains[i];
 
 		if (rd->id == RAPL_DOMAIN_PACKAGE)
 			continue;
@@ -1302,7 +1304,6 @@ static void rapl_detect_powerlimit(struct rapl_domain *rd)
  */
 static int rapl_detect_domains(struct rapl_package *rp, int cpu)
 {
-	struct rapl_domain *rd;
 	int i;
 
 	for (i = 0; i < RAPL_DOMAIN_MAX; i++) {
@@ -1319,15 +1320,15 @@ static int rapl_detect_domains(struct rapl_package *rp, int cpu)
 	}
 	pr_debug("found %d domains on %s\n", rp->nr_domains, rp->name);
 
-	rp->domains = kcalloc(rp->nr_domains + 1, sizeof(struct rapl_domain),
+	rp->domains = kcalloc(rp->nr_domains, sizeof(struct rapl_domain),
 			      GFP_KERNEL);
 	if (!rp->domains)
 		return -ENOMEM;
 
 	rapl_init_domains(rp);
 
-	for (rd = rp->domains; rd < rp->domains + rp->nr_domains; rd++)
-		rapl_detect_powerlimit(rd);
+	for (i = 0; i < rp->nr_domains; i++)
+		rapl_detect_powerlimit(&rp->domains[i]);
 
 	return 0;
 }
-- 
2.34.1