[PATCH 08/14] drm/amd/pm: Replace one-element array with flexible-array in struct phm_cac_leakage_table

Gustavo A. R. Silva
2020-10-07T16:01:40Z

struct phm_cac_leakage_table, instead of a one-element array,
and use the struct_size() helper to calculate the size for the allocation.

Also, save some heap space as the original code is multiplying
table->ucNumEntries by sizeof(struct phm_cac_leakage_table) when it
should have been multiplied it by sizeof(struct phm_cac_leakage_record)
instead.

[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@intel.com>
Link: https://lore.kernel.org/lkml/5f7c5d38.iT%2FQTjN+659XUDo5%25lkp@intel.com/
Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
---
drivers/gpu/drm/amd/pm/inc/hwmgr.h | 2 +-
.../drm/amd/pm/powerplay/hwmgr/processpptables.c | 13 +++++--------
2 files changed, 6 insertions(+), 9 deletions(-)

diff --git a/drivers/gpu/drm/amd/pm/inc/hwmgr.h b/drivers/gpu/drm/amd/pm/inc/hwmgr.h
index b8e33325fac6..7e0c948a7097 100644
--- a/drivers/gpu/drm/amd/pm/inc/hwmgr.h
+++ b/drivers/gpu/drm/amd/pm/inc/hwmgr.h
@@ -393,7 +393,7 @@ union phm_cac_leakage_record {

struct phm_cac_leakage_table {
uint32_t count;
- union phm_cac_leakage_record entries[1];
+ union phm_cac_leakage_record entries[];
};

struct phm_samu_clock_voltage_dependency_record {
diff --git a/drivers/gpu/drm/amd/pm/powerplay/hwmgr/processpptables.c b/drivers/gpu/drm/amd/pm/powerplay/hwmgr/processpptables.c
index 7719f52e6d52..e059802d1e25 100644
--- a/drivers/gpu/drm/amd/pm/powerplay/hwmgr/processpptables.c
+++ b/drivers/gpu/drm/amd/pm/powerplay/hwmgr/processpptables.c
@@ -1384,17 +1384,14 @@ static int get_cac_leakage_table(struct pp_hwmgr *hwmgr,
const ATOM_PPLIB_CAC_Leakage_Table *table)
{
struct phm_cac_leakage_table *cac_leakage_table;
- unsigned long table_size, i;
+ unsigned long i;

- if (hwmgr == NULL || table == NULL || ptable == NULL)
+ if (!hwmgr || !table || !ptable)
return -EINVAL;

- table_size = sizeof(ULONG) +
- (sizeof(struct phm_cac_leakage_table) * table->ucNumEntries);
-
- cac_leakage_table = kzalloc(table_size, GFP_KERNEL);
-
- if (cac_leakage_table == NULL)
+ cac_leakage_table = kzalloc(struct_size(cac_leakage_table, entries, table->ucNumEntries),
+ GFP_KERNEL);
+ if (!cac_leakage_table)
return -ENOMEM;

cac_leakage_table->count = (ULONG)table->ucNumEntries;
--
2.27.0