Commit 9526e431 authored by Gustavo A. R. Silva's avatar Gustavo A. R. Silva Committed by Alex Deucher
Browse files

drm/amd/pm: Replace one-element array with flexible-array in struct phm_phase_shedding_limits_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_phase_shedding_limits_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
ptable->ucNumEntries by sizeof(struct phm_phase_shedding_limits_table)
when it should have multiplied it by sizeof(struct phm_phase_shedding_limits_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: default avatarkernel test robot <lkp@intel.com>
Link: https://lore.kernel.org/lkml/5f7c5d36.6PStUZp2HRxAz7IM%25lkp@intel.com/


Acked-by: default avatarChristian König <christian.koenig@amd.com>
Signed-off-by: default avatarGustavo A. R. Silva <gustavoars@kernel.org>
Signed-off-by: default avatarAlex Deucher <alexander.deucher@amd.com>
parent 0e319cfe

drivers/gpu/drm/amd/pm/inc/hwmgr.h

+1 −1
Original line number Diff line number Diff line
@@ -161,7 +161,7 @@ struct phm_vce_clock_voltage_dependency_record { 


struct phm_phase_shedding_limits_table {

	uint32_t                           count;

	struct phm_phase_shedding_limits_record  entries[1];

	struct phm_phase_shedding_limits_record  entries[];

};



struct phm_vceclock_voltage_dependency_table {

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

+4 −8
Original line number Diff line number Diff line
@@ -1530,16 +1530,12 @@ static int init_phase_shedding_table(struct pp_hwmgr *hwmgr, 
				(((unsigned long)powerplay_table4) +

				le16_to_cpu(powerplay_table4->usVddcPhaseShedLimitsTableOffset));

			struct phm_phase_shedding_limits_table *table;

			unsigned long size, i;





			size = sizeof(unsigned long) +

				(sizeof(struct phm_phase_shedding_limits_table) *

				ptable->ucNumEntries);

			unsigned long i;



			table = kzalloc(size, GFP_KERNEL);



			if (table == NULL)

			table = kzalloc(struct_size(table, entries, ptable->ucNumEntries),

					GFP_KERNEL);

			if (!table)

				return -ENOMEM;



			table->count = (unsigned long)ptable->ucNumEntries;