[PATCH 01/14] drm/amd/pm: Replace one-element array with flexible-array member

From: Gustavo A. R. Silva
Date: Wed Oct 07 2020 - 11:56:28 EST


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_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-arrays

Build-tested-by: kernel test robot <lkp@xxxxxxxxx>
Link: https://lore.kernel.org/lkml/5f7c295c.8iqp1Ifc6oiVDq%2F%2F%25lkp@xxxxxxxxx/
Signed-off-by: Gustavo A. R. Silva <gustavoars@xxxxxxxxxx>
---
drivers/gpu/drm/amd/pm/inc/hwmgr.h | 4 ++--
drivers/gpu/drm/amd/pm/powerplay/hwmgr/processpptables.c | 9 +++------
drivers/gpu/drm/amd/pm/powerplay/hwmgr/smu8_hwmgr.c | 2 +-
drivers/gpu/drm/amd/pm/powerplay/hwmgr/smu_helper.c | 5 ++---
4 files changed, 8 insertions(+), 12 deletions(-)

diff --git a/drivers/gpu/drm/amd/pm/inc/hwmgr.h b/drivers/gpu/drm/amd/pm/inc/hwmgr.h
index 3898a95ec28b..a1dbfd5636e6 100644
--- a/drivers/gpu/drm/amd/pm/inc/hwmgr.h
+++ b/drivers/gpu/drm/amd/pm/inc/hwmgr.h
@@ -122,8 +122,8 @@ struct phm_acpclock_voltage_dependency_record {
};

struct phm_clock_voltage_dependency_table {
- uint32_t count; /* Number of entries. */
- struct phm_clock_voltage_dependency_record entries[1]; /* Dynamically allocate count entries. */
+ uint32_t count; /* Number of entries. */
+ struct phm_clock_voltage_dependency_record entries[]; /* Dynamically allocate count entries. */
};

struct phm_phase_shedding_limits_record {
diff --git a/drivers/gpu/drm/amd/pm/powerplay/hwmgr/processpptables.c b/drivers/gpu/drm/amd/pm/powerplay/hwmgr/processpptables.c
index 719597c5d27d..d94a7d8e0587 100644
--- a/drivers/gpu/drm/amd/pm/powerplay/hwmgr/processpptables.c
+++ b/drivers/gpu/drm/amd/pm/powerplay/hwmgr/processpptables.c
@@ -377,14 +377,11 @@ static int get_clock_voltage_dependency_table(struct pp_hwmgr *hwmgr,
const ATOM_PPLIB_Clock_Voltage_Dependency_Table *table)
{

- unsigned long table_size, i;
+ unsigned long i;
struct phm_clock_voltage_dependency_table *dep_table;

- table_size = sizeof(unsigned long) +
- sizeof(struct phm_clock_voltage_dependency_table)
- * table->ucNumEntries;
-
- dep_table = kzalloc(table_size, GFP_KERNEL);
+ dep_table = kzalloc(struct_size(dep_table, entries, table->ucNumEntries),
+ GFP_KERNEL);
if (NULL == dep_table)
return -ENOMEM;

diff --git a/drivers/gpu/drm/amd/pm/powerplay/hwmgr/smu8_hwmgr.c b/drivers/gpu/drm/amd/pm/powerplay/hwmgr/smu8_hwmgr.c
index 35ed47ebaf09..ed9b89980184 100644
--- a/drivers/gpu/drm/amd/pm/powerplay/hwmgr/smu8_hwmgr.c
+++ b/drivers/gpu/drm/amd/pm/powerplay/hwmgr/smu8_hwmgr.c
@@ -276,7 +276,7 @@ static int smu8_init_dynamic_state_adjustment_rule_settings(
{
struct phm_clock_voltage_dependency_table *table_clk_vlt;

- table_clk_vlt = kzalloc(struct_size(table_clk_vlt, entries, 7),
+ table_clk_vlt = kzalloc(struct_size(table_clk_vlt, entries, 8),
GFP_KERNEL);

if (NULL == table_clk_vlt) {
diff --git a/drivers/gpu/drm/amd/pm/powerplay/hwmgr/smu_helper.c b/drivers/gpu/drm/amd/pm/powerplay/hwmgr/smu_helper.c
index 60b5ca974356..b485f8b1d6f2 100644
--- a/drivers/gpu/drm/amd/pm/powerplay/hwmgr/smu_helper.c
+++ b/drivers/gpu/drm/amd/pm/powerplay/hwmgr/smu_helper.c
@@ -492,13 +492,12 @@ int phm_get_sclk_for_voltage_evv(struct pp_hwmgr *hwmgr,
*/
int phm_initializa_dynamic_state_adjustment_rule_settings(struct pp_hwmgr *hwmgr)
{
- uint32_t table_size;
struct phm_clock_voltage_dependency_table *table_clk_vlt;
struct phm_ppt_v1_information *pptable_info = (struct phm_ppt_v1_information *)(hwmgr->pptable);

/* initialize vddc_dep_on_dal_pwrl table */
- table_size = sizeof(uint32_t) + 4 * sizeof(struct phm_clock_voltage_dependency_record);
- table_clk_vlt = kzalloc(table_size, GFP_KERNEL);
+ table_clk_vlt = kzalloc(struct_size(table_clk_vlt, entries, 4),
+ GFP_KERNEL);

if (NULL == table_clk_vlt) {
pr_err("Can not allocate space for vddc_dep_on_dal_pwrl! \n");
--
2.27.0