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

drm/amd/pm: Replace one-element array with flexible-array in struct phm_ppt_v1_clock_voltage_dependency_table

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_ppt_v1_clock_voltage_dependency_table, 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/5f7c433c.TTk9rnA+F58kyDUy%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/powerplay/hwmgr/hwmgr_ppt.h

@@ -48,7 +48,7 @@ typedef struct phm_ppt_v1_clock_voltage_dependency_record phm_ppt_v1_clock_volta
 
 struct phm_ppt_v1_clock_voltage_dependency_table {
 	uint32_t count;                                            /* Number of entries. */
-	phm_ppt_v1_clock_voltage_dependency_record entries[1];     /* Dynamically allocate count entries. */
+	phm_ppt_v1_clock_voltage_dependency_record entries[];	   /* Dynamically allocate count entries. */
 };
 
 typedef struct phm_ppt_v1_clock_voltage_dependency_table phm_ppt_v1_clock_voltage_dependency_table;

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

@@ -367,7 +367,7 @@ static int get_mclk_voltage_dependency_table(
 		ATOM_Tonga_MCLK_Dependency_Table const *mclk_dep_table
 		)
 {
-	uint32_t table_size, i;
+	uint32_t i;
 	phm_ppt_v1_clock_voltage_dependency_table *mclk_table;
 	phm_ppt_v1_clock_voltage_dependency_record *mclk_table_record;
 	ATOM_Tonga_MCLK_Dependency_Record *mclk_dep_record;
@@ -375,12 +375,9 @@ static int get_mclk_voltage_dependency_table(
 	PP_ASSERT_WITH_CODE((0 != mclk_dep_table->ucNumEntries),
 		"Invalid PowerPlay Table!", return -1);
 
-	table_size = sizeof(uint32_t) + sizeof(phm_ppt_v1_clock_voltage_dependency_record)
-		* mclk_dep_table->ucNumEntries;
-
-	mclk_table = kzalloc(table_size, GFP_KERNEL);
-
-	if (NULL == mclk_table)
+	mclk_table = kzalloc(struct_size(mclk_table, entries, mclk_dep_table->ucNumEntries),
+			     GFP_KERNEL);
+	if (!mclk_table)
 		return -ENOMEM;
 
 	mclk_table->count = (uint32_t)mclk_dep_table->ucNumEntries;
@@ -410,7 +407,7 @@ static int get_sclk_voltage_dependency_table(
 		PPTable_Generic_SubTable_Header const  *sclk_dep_table
 		)
 {
-	uint32_t table_size, i;
+	uint32_t i;
 	phm_ppt_v1_clock_voltage_dependency_table *sclk_table;
 	phm_ppt_v1_clock_voltage_dependency_record *sclk_table_record;
 
@@ -422,12 +419,9 @@ static int get_sclk_voltage_dependency_table(
 		PP_ASSERT_WITH_CODE((0 != tonga_table->ucNumEntries),
 			"Invalid PowerPlay Table!", return -1);
 
-		table_size = sizeof(uint32_t) + sizeof(phm_ppt_v1_clock_voltage_dependency_record)
-			* tonga_table->ucNumEntries;
-
-		sclk_table = kzalloc(table_size, GFP_KERNEL);
-
-		if (NULL == sclk_table)
+		sclk_table = kzalloc(struct_size(sclk_table, entries, tonga_table->ucNumEntries),
+				     GFP_KERNEL);
+		if (!sclk_table)
 			return -ENOMEM;
 
 		sclk_table->count = (uint32_t)tonga_table->ucNumEntries;
@@ -454,12 +448,9 @@ static int get_sclk_voltage_dependency_table(
 		PP_ASSERT_WITH_CODE((0 != polaris_table->ucNumEntries),
 			"Invalid PowerPlay Table!", return -1);
 
-		table_size = sizeof(uint32_t) + sizeof(phm_ppt_v1_clock_voltage_dependency_record)
-			* polaris_table->ucNumEntries;
-
-		sclk_table = kzalloc(table_size, GFP_KERNEL);
-
-		if (NULL == sclk_table)
+		sclk_table = kzalloc(struct_size(sclk_table, entries, polaris_table->ucNumEntries),
+				     GFP_KERNEL);
+		if (!sclk_table)
 			return -ENOMEM;
 
 		sclk_table->count = (uint32_t)polaris_table->ucNumEntries;

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

@@ -571,18 +571,14 @@ static int get_socclk_voltage_dependency_table(
 		phm_ppt_v1_clock_voltage_dependency_table **pp_vega10_clk_dep_table,
 		const ATOM_Vega10_SOCCLK_Dependency_Table *clk_dep_table)
 {
-	uint32_t table_size, i;
+	uint32_t i;
 	phm_ppt_v1_clock_voltage_dependency_table *clk_table;
 
 	PP_ASSERT_WITH_CODE(clk_dep_table->ucNumEntries,
 		"Invalid PowerPlay Table!", return -1);
 
-	table_size = sizeof(uint32_t) +
-			sizeof(phm_ppt_v1_clock_voltage_dependency_record) *
-			clk_dep_table->ucNumEntries;
-
-	clk_table = kzalloc(table_size, GFP_KERNEL);
-
+	clk_table = kzalloc(struct_size(clk_table, entries, clk_dep_table->ucNumEntries),
+			    GFP_KERNEL);
 	if (!clk_table)
 		return -ENOMEM;
 
@@ -605,18 +601,14 @@ static int get_mclk_voltage_dependency_table(
 		phm_ppt_v1_clock_voltage_dependency_table **pp_vega10_mclk_dep_table,
 		const ATOM_Vega10_MCLK_Dependency_Table *mclk_dep_table)
 {
-	uint32_t table_size, i;
+	uint32_t i;
 	phm_ppt_v1_clock_voltage_dependency_table *mclk_table;
 
 	PP_ASSERT_WITH_CODE(mclk_dep_table->ucNumEntries,
 		"Invalid PowerPlay Table!", return -1);
 
-	table_size = sizeof(uint32_t) +
-			sizeof(phm_ppt_v1_clock_voltage_dependency_record) *
-			mclk_dep_table->ucNumEntries;
-
-	mclk_table = kzalloc(table_size, GFP_KERNEL);
-
+	mclk_table = kzalloc(struct_size(mclk_table, entries, mclk_dep_table->ucNumEntries),
+			    GFP_KERNEL);
 	if (!mclk_table)
 		return -ENOMEM;
 
@@ -644,7 +636,7 @@ static int get_gfxclk_voltage_dependency_table(
 			**pp_vega10_clk_dep_table,
 		const ATOM_Vega10_GFXCLK_Dependency_Table *clk_dep_table)
 {
-	uint32_t table_size, i;
+	uint32_t i;
 	struct phm_ppt_v1_clock_voltage_dependency_table
 				*clk_table;
 	ATOM_Vega10_GFXCLK_Dependency_Record_V2 *patom_record_v2;
@@ -652,12 +644,8 @@ static int get_gfxclk_voltage_dependency_table(
 	PP_ASSERT_WITH_CODE((clk_dep_table->ucNumEntries != 0),
 			"Invalid PowerPlay Table!", return -1);
 
-	table_size = sizeof(uint32_t) +
-			sizeof(phm_ppt_v1_clock_voltage_dependency_record) *
-			clk_dep_table->ucNumEntries;
-
-	clk_table = kzalloc(table_size, GFP_KERNEL);
-
+	clk_table = kzalloc(struct_size(clk_table, entries, clk_dep_table->ucNumEntries),
+			    GFP_KERNEL);
 	if (!clk_table)
 		return -ENOMEM;
 
@@ -711,19 +699,15 @@ static int get_pix_clk_voltage_dependency_table(
 			**pp_vega10_clk_dep_table,
 		const  ATOM_Vega10_PIXCLK_Dependency_Table *clk_dep_table)
 {
-	uint32_t table_size, i;
+	uint32_t i;
 	struct phm_ppt_v1_clock_voltage_dependency_table
 				*clk_table;
 
 	PP_ASSERT_WITH_CODE((clk_dep_table->ucNumEntries != 0),
 			"Invalid PowerPlay Table!", return -1);
 
-	table_size = sizeof(uint32_t) +
-			sizeof(phm_ppt_v1_clock_voltage_dependency_record) *
-			clk_dep_table->ucNumEntries;
-
-	clk_table = kzalloc(table_size, GFP_KERNEL);
-
+	clk_table = kzalloc(struct_size(clk_table, entries, clk_dep_table->ucNumEntries),
+			    GFP_KERNEL);
 	if (!clk_table)
 		return -ENOMEM;
 
@@ -747,7 +731,7 @@ static int get_dcefclk_voltage_dependency_table(
 			**pp_vega10_clk_dep_table,
 		const ATOM_Vega10_DCEFCLK_Dependency_Table *clk_dep_table)
 {
-	uint32_t table_size, i;
+	uint32_t i;
 	uint8_t num_entries;
 	struct phm_ppt_v1_clock_voltage_dependency_table
 				*clk_table;
@@ -775,12 +759,8 @@ static int get_dcefclk_voltage_dependency_table(
 		num_entries = clk_dep_table->ucNumEntries;
 
 
-	table_size = sizeof(uint32_t) +
-			sizeof(phm_ppt_v1_clock_voltage_dependency_record) *
-			num_entries;
-
-	clk_table = kzalloc(table_size, GFP_KERNEL);
-
+	clk_table = kzalloc(struct_size(clk_table, entries, num_entries),
+			    GFP_KERNEL);
 	if (!clk_table)
 		return -ENOMEM;