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

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

Also, this helps with the ongoing efforts to enable -Warray-bounds and
fix the following warnings:

drivers/gpu/drm/amd/amdgpu/../pm/powerplay/si_dpm.c:2448:20: warning: array
subscript 1 is above array bounds of ‘SISLANDS_SMC_HW_PERFORMANCE_LEVEL[1]’
{aka ‘struct SISLANDS_SMC_HW_PERFORMANCE_LEVEL[1]’} [-Warray-bounds]
drivers/gpu/drm/amd/amdgpu/../pm/powerplay/si_dpm.c:2449:20: warning: array
subscript 1 is above array bounds of ‘SISLANDS_SMC_HW_PERFORMANCE_LEVEL[1]’
{aka ‘struct SISLANDS_SMC_HW_PERFORMANCE_LEVEL[1]’} [-Warray-bounds]
drivers/gpu/drm/amd/amdgpu/../pm/powerplay/si_dpm.c:2450:20: warning: array
subscript 1 is above array bounds of ‘SISLANDS_SMC_HW_PERFORMANCE_LEVEL[1]’
{aka ‘struct SISLANDS_SMC_HW_PERFORMANCE_LEVEL[1]’} [-Warray-bounds]
drivers/gpu/drm/amd/amdgpu/../pm/powerplay/si_dpm.c:2451:20: warning: array
subscript 1 is above array bounds of ‘SISLANDS_SMC_HW_PERFORMANCE_LEVEL[1]’
{aka ‘struct SISLANDS_SMC_HW_PERFORMANCE_LEVEL[1]’} [-Warray-bounds]
drivers/gpu/drm/amd/amdgpu/../pm/powerplay/si_dpm.c:2452:20: warning: array
subscript 1 is above array bounds of ‘SISLANDS_SMC_HW_PERFORMANCE_LEVEL[1]’
{aka ‘struct SISLANDS_SMC_HW_PERFORMANCE_LEVEL[1]’} [-Warray-bounds]
drivers/gpu/drm/amd/amdgpu/../pm/powerplay/si_dpm.c:5570:20: warning: array
subscript 1 is above array bounds of ‘SISLANDS_SMC_HW_PERFORMANCE_LEVEL[1]’
{aka ‘struct SISLANDS_SMC_HW_PERFORMANCE_LEVEL[1]’} [-Warray-bounds]

[1] https://en.wikipedia.org/wiki/Flexible_array_member
[2] https://www.kernel.org/doc/html/v5.9/process/deprecated.html#zero-length-and-one-element-arrays

Link: https://github.com/KSPP/linux/issues/79
Link: https://github.com/KSPP/linux/issues/109
Build-tested-by: kernel test robot <lkp@intel.com>
Link: https://lore.kernel.org/lkml/6023be58.sk66L%2FV4vuSJI5mI%25lkp@intel.com/
Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
This commit is contained in:
Gustavo A. R. Silva 2021-02-10 16:40:31 -06:00 • committed by Alex Deucher
parent ce7c670dd1
commit 0e1aa13ca3
2 changed files with 7 additions and 9 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

6
drivers/gpu/drm/amd/pm/powerplay/si_dpm.c
View file

@ -5715,11 +5715,9 @@ static int si_upload_sw_state(struct amdgpu_device *adev,
int ret;
u32 address = si_pi->state_table_start +
offsetof(SISLANDS_SMC_STATETABLE, driverState);
u32 state_size = sizeof(SISLANDS_SMC_SWSTATE) +
((new_state->performance_level_count - 1) *
sizeof(SISLANDS_SMC_HW_PERFORMANCE_LEVEL));
SISLANDS_SMC_SWSTATE *smc_state = &si_pi->smc_statetable.driverState;
size_t state_size = struct_size(smc_state, levels,
new_state->performance_level_count);
memset(smc_state, 0, state_size);
ret = si_convert_power_state_to_smc(adev, amdgpu_new_state, smc_state);

10
drivers/gpu/drm/amd/pm/powerplay/sislands_smc.h
View file

@ -182,11 +182,11 @@ typedef struct SISLANDS_SMC_HW_PERFORMANCE_LEVEL SISLANDS_SMC_HW_PERFORMANCE_LEV
struct SISLANDS_SMC_SWSTATE
{
uint8_t flags;
uint8_t levelCount;
uint8_t padding2;
uint8_t padding3;
SISLANDS_SMC_HW_PERFORMANCE_LEVEL levels[1];
uint8_t flags;
uint8_t levelCount;
uint8_t padding2;
uint8_t padding3;
SISLANDS_SMC_HW_PERFORMANCE_LEVEL levels[];
};
typedef struct SISLANDS_SMC_SWSTATE SISLANDS_SMC_SWSTATE;