drm/amd/pm: Replace one-element array with flexible-array in struct phm_clock_array

There is a regular need in the kernel to provide a way to declare having
a dynamically sized set of trailing elements in a structure. Kernel code
should always use “flexible array members”[1] for these cases. The older
style of one-element or zero-length arrays should no longer be used[2].

Refactor the code according to the use of a flexible-array member in
struct phm_clock_array, instead of a one-element array, and use the
struct_size() helper to calculate the size for the allocation.

[1] https://en.wikipedia.org/wiki/Flexible_array_member
[2] https://www.kernel.org/doc/html/v5.9-rc1/process/deprecated.html#zero-length-and-one-element-arraysBuild-tested-by: kernel test robot <lkp@intel.com>
Link: https://lore.kernel.org/lkml/5f7c433f.ZyMD+YUIVAwiHGVe%25lkp@intel.com/Acked-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/pm/inc/hwmgr.h

@@ -91,7 +91,7 @@ struct phm_set_power_state_input {
 
 struct phm_clock_array {
 	uint32_t count;
-	uint32_t values[1];
+	uint32_t values[];
 };
 
 struct phm_clock_voltage_dependency_record {

drivers/gpu/drm/amd/pm/powerplay/hwmgr/process_pptables_v1_0.c

@@ -318,19 +318,16 @@ static int get_valid_clk(
 		phm_ppt_v1_clock_voltage_dependency_table const *clk_volt_pp_table
 		)
 {
-	uint32_t table_size, i;
+	uint32_t i;
 	struct phm_clock_array *table;
 	phm_ppt_v1_clock_voltage_dependency_record *dep_record;
 
 	PP_ASSERT_WITH_CODE((0 != clk_volt_pp_table->count),
 		"Invalid PowerPlay Table!", return -1);
 
-	table_size = sizeof(uint32_t) +
-		sizeof(uint32_t) * clk_volt_pp_table->count;
-
-	table = kzalloc(table_size, GFP_KERNEL);
-
-	if (NULL == table)
+	table = kzalloc(struct_size(table, values, clk_volt_pp_table->count),
+			GFP_KERNEL);
+	if (!table)
 		return -ENOMEM;
 
 	table->count = (uint32_t)clk_volt_pp_table->count;

drivers/gpu/drm/amd/pm/powerplay/hwmgr/processpptables.c

@@ -404,12 +404,11 @@ static int get_valid_clk(struct pp_hwmgr *hwmgr,
 			struct phm_clock_array **ptable,
 			const struct phm_clock_voltage_dependency_table *table)
 {
-	unsigned long table_size, i;
+	unsigned long i;
 	struct phm_clock_array *clock_table;
 
-	table_size = sizeof(unsigned long) + sizeof(unsigned long) * table->count;
-	clock_table = kzalloc(table_size, GFP_KERNEL);
-	if (NULL == clock_table)
+	clock_table = kzalloc(struct_size(clock_table, values, table->count), GFP_KERNEL);
+	if (!clock_table)
 		return -ENOMEM;
 
 	clock_table->count = (unsigned long)table->count;

drivers/gpu/drm/amd/pm/powerplay/hwmgr/vega10_processpptables.c

@@ -875,17 +875,14 @@ static int get_valid_clk(
 		struct phm_clock_array **clk_table,
 		const phm_ppt_v1_clock_voltage_dependency_table *clk_volt_pp_table)
 {
-	uint32_t table_size, i;
+	uint32_t i;
 	struct phm_clock_array *table;
 
 	PP_ASSERT_WITH_CODE(clk_volt_pp_table->count,
 			"Invalid PowerPlay Table!", return -1);
 
-	table_size = sizeof(uint32_t) +
-			sizeof(uint32_t) * clk_volt_pp_table->count;
-
-	table = kzalloc(table_size, GFP_KERNEL);
-
+	table = kzalloc(struct_size(table, values, clk_volt_pp_table->count),
+			GFP_KERNEL);
 	if (!table)
 		return -ENOMEM;