Re: [PATCH][next] drm/radeon/si_dpm: Replace one-element array with flexible-array in struct SISLANDS_SMC_SWSTATE

2021-03-05 Thread Gustavo A. R. Silva 
On Fri, Mar 05, 2021 at 02:10:44PM -0500, Alex Deucher wrote:
> Applied.  Thanks!

Awesome. :)

Thanks, Alex.
--
Gustavo
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Re: [PATCH][next] drm/radeon/si_dpm: Replace one-element array with flexible-array in struct SISLANDS_SMC_SWSTATE

2021-03-05 Thread Alex Deucher 
Applied.  Thanks!

Alex

On Wed, Mar 3, 2021 at 2:05 PM Gustavo A. R. Silva
 wrote:
>
> 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 by
> fixing the following warnings:
>
> drivers/gpu/drm/radeon/si_dpm.c: In function ‘si_convert_power_state_to_smc’:
> drivers/gpu/drm/radeon/si_dpm.c:2350:20: 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]
>  2350 |   smc_state->levels[i].dpm2.MaxPS = 
> (u8)((SISLANDS_DPM2_MAX_PULSE_SKIP * (max_sclk - min_sclk)) / max_sclk);
>   |   ~^~~
> drivers/gpu/drm/radeon/si_dpm.c:2351:20: 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]
>  2351 |   smc_state->levels[i].dpm2.NearTDPDec = SISLANDS_DPM2_NEAR_TDP_DEC;
>   |   ~^~~
> drivers/gpu/drm/radeon/si_dpm.c:2352:20: 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]
>  2352 |   smc_state->levels[i].dpm2.AboveSafeInc = 
> SISLANDS_DPM2_ABOVE_SAFE_INC;
>   |   ~^~~
> drivers/gpu/drm/radeon/si_dpm.c:2353:20: 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]
>  2353 |   smc_state->levels[i].dpm2.BelowSafeInc = 
> SISLANDS_DPM2_BELOW_SAFE_INC;
>   |   ~^~~
> drivers/gpu/drm/radeon/si_dpm.c:2354:20: 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]
>  2354 |   smc_state->levels[i].dpm2.PwrEfficiencyRatio = 
> cpu_to_be16(pwr_efficiency_ratio);
>   |   ~^~~
> drivers/gpu/drm/radeon/si_dpm.c:5105:20: 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]
>  5105 |   smc_state->levels[i + 1].aT = cpu_to_be32(a_t);
>   |   ~^~~
>
> [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 
> Link: https://lore.kernel.org/lkml/603f9a8f.adlrpmfzzsapzvyq%25...@intel.com/
> Signed-off-by: Gustavo A. R. Silva 
> ---
>  drivers/gpu/drm/radeon/si_dpm.c   |  5 ++---
>  drivers/gpu/drm/radeon/sislands_smc.h | 10 +-
>  2 files changed, 7 insertions(+), 8 deletions(-)
>
> diff --git a/drivers/gpu/drm/radeon/si_dpm.c b/drivers/gpu/drm/radeon/si_dpm.c
> index 91bfc4762767..918609551804 100644
> --- a/drivers/gpu/drm/radeon/si_dpm.c
> +++ b/drivers/gpu/drm/radeon/si_dpm.c
> @@ -5250,10 +5250,9 @@ static int si_upload_sw_state(struct radeon_device 
> *rdev,
> 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 = _pi->smc_statetable.driverState;
> +   size_t state_size = struct_size(smc_state, levels,
> +   new_state->performance_level_count);
>
> memset(smc_state, 0, state_size);
>
> diff --git a/drivers/gpu/drm/radeon/sislands_smc.h 
> b/drivers/gpu/drm/radeon/sislands_smc.h
> index 966e3a556011..fbd6589bdab9 100644
> --- a/drivers/gpu/drm/radeon/sislands_smc.h
> +++ b/drivers/gpu/drm/radeon/sislands_smc.h
> @@ -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;
> +

[PATCH][next] drm/radeon/si_dpm: Replace one-element array with flexible-array in struct SISLANDS_SMC_SWSTATE

2021-03-03 Thread Gustavo A. R. Silva 
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 by
fixing the following warnings:

drivers/gpu/drm/radeon/si_dpm.c: In function ‘si_convert_power_state_to_smc’:
drivers/gpu/drm/radeon/si_dpm.c:2350:20: 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]
 2350 |   smc_state->levels[i].dpm2.MaxPS = (u8)((SISLANDS_DPM2_MAX_PULSE_SKIP 
* (max_sclk - min_sclk)) / max_sclk);
  |   ~^~~
drivers/gpu/drm/radeon/si_dpm.c:2351:20: 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]
 2351 |   smc_state->levels[i].dpm2.NearTDPDec = SISLANDS_DPM2_NEAR_TDP_DEC;
  |   ~^~~
drivers/gpu/drm/radeon/si_dpm.c:2352:20: 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]
 2352 |   smc_state->levels[i].dpm2.AboveSafeInc = SISLANDS_DPM2_ABOVE_SAFE_INC;
  |   ~^~~
drivers/gpu/drm/radeon/si_dpm.c:2353:20: 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]
 2353 |   smc_state->levels[i].dpm2.BelowSafeInc = SISLANDS_DPM2_BELOW_SAFE_INC;
  |   ~^~~
drivers/gpu/drm/radeon/si_dpm.c:2354:20: 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]
 2354 |   smc_state->levels[i].dpm2.PwrEfficiencyRatio = 
cpu_to_be16(pwr_efficiency_ratio);
  |   ~^~~
drivers/gpu/drm/radeon/si_dpm.c:5105:20: 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]
 5105 |   smc_state->levels[i + 1].aT = cpu_to_be32(a_t);
  |   ~^~~

[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 
Link: https://lore.kernel.org/lkml/603f9a8f.adlrpmfzzsapzvyq%25...@intel.com/
Signed-off-by: Gustavo A. R. Silva 
---
 drivers/gpu/drm/radeon/si_dpm.c   |  5 ++---
 drivers/gpu/drm/radeon/sislands_smc.h | 10 +-
 2 files changed, 7 insertions(+), 8 deletions(-)

diff --git a/drivers/gpu/drm/radeon/si_dpm.c b/drivers/gpu/drm/radeon/si_dpm.c
index 91bfc4762767..918609551804 100644
--- a/drivers/gpu/drm/radeon/si_dpm.c
+++ b/drivers/gpu/drm/radeon/si_dpm.c
@@ -5250,10 +5250,9 @@ static int si_upload_sw_state(struct radeon_device *rdev,
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 = _pi->smc_statetable.driverState;
+   size_t state_size = struct_size(smc_state, levels,
+   new_state->performance_level_count);
 
memset(smc_state, 0, state_size);
 
diff --git a/drivers/gpu/drm/radeon/sislands_smc.h 
b/drivers/gpu/drm/radeon/sislands_smc.h
index 966e3a556011..fbd6589bdab9 100644
--- a/drivers/gpu/drm/radeon/sislands_smc.h
+++ b/drivers/gpu/drm/radeon/sislands_smc.h
@@ -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;
-- 
2.27.0