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