drm/amd/powerplay/smu8_hwmgr: use struct_size() in kzalloc()

GustavoARSilva · alexdeucher · commit 7f5725f98025 · 2019-02-19T15:58:27.000-05:00
One of the more common cases of allocation size calculations is finding
the size of a structure that has a zero-sized array at the end, along
with memory for some number of elements for that array. For example:

struct foo {
    int stuff;
    struct boo entry[];
};

size = sizeof(struct foo) + count * sizeof(struct boo);
instance = kzalloc(size, GFP_KERNEL);

Instead of leaving these open-coded and prone to type mistakes, we can
now use the new struct_size() helper:

instance = kzalloc(struct_size(instance, entry, count), GFP_KERNEL);

Notice that, in this case, variable table_size is not necessary, hence
it is removed.

This code was detected with the help of Coccinelle.

Signed-off-by: Gustavo A. R. Silva &lt;gustavo@embeddedor.com&gt;
Signed-off-by: Alex Deucher &lt;alexander.deucher@amd.com&gt;
diff --git a/drivers/gpu/drm/amd/powerplay/hwmgr/smu8_hwmgr.c b/drivers/gpu/drm/amd/powerplay/hwmgr/smu8_hwmgr.c
@@ -272,12 +272,10 @@ static int smu8_init_dynamic_state_adjustment_rule_settings(
 			struct pp_hwmgr *hwmgr,
 			ATOM_CLK_VOLT_CAPABILITY *disp_voltage_table)
 {
-	uint32_t table_size =
-		sizeof(struct phm_clock_voltage_dependency_table) +
-		(7 * sizeof(struct phm_clock_voltage_dependency_record));
+	struct phm_clock_voltage_dependency_table *table_clk_vlt;
 
-	struct phm_clock_voltage_dependency_table *table_clk_vlt =
-					kzalloc(table_size, GFP_KERNEL);
+	table_clk_vlt = kzalloc(struct_size(table_clk_vlt, entries, 7),
+				GFP_KERNEL);
 
 	if (NULL == table_clk_vlt) {
 		pr_err("Can not allocate memory!\n");
