Replace struct_size() with sizeof(), and avoid allocating 8 too many
bytes.

The following difference in binary output is expected and reflects the
desired change:

| net/sched/cls_u32.o
| @@ -6148,7 +6148,7 @@
| include/linux/slab.h:599
|     2cf5:      mov    0x0(%rip),%rdi        # 2cfc <u32_init+0xfc>
|                        2cf8: R_X86_64_PC32     kmalloc_caches+0xc
|-    2cfc:      mov    $0x98,%edx
|+    2cfc:      mov    $0x90,%edx

Fixes: d61491a51f7e ("net/sched: cls_u32: Replace one-element array with flexible-array member")
Reported-by: Alejandro Colomar <alx@kernel.org>
Closes: https://lore.kernel.org/lkml/09b4a2ce-da74-3a19-6961-67883f634d98@kernel.org/ (local)
Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
---
 net/sched/cls_u32.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/sched/cls_u32.c b/net/sched/cls_u32.c
index da4c179a4d41..6663e971a13e 100644
--- a/net/sched/cls_u32.c
+++ b/net/sched/cls_u32.c

@@ -366,7 +366,7 @@ static int u32_init(struct tcf_proto *tp)
        idr_init(&root_ht->handle_idr);

        if (tp_c == NULL) {
-               tp_c = kzalloc(struct_size(tp_c, hlist->ht, 1), GFP_KERNEL);
+               tp_c = kzalloc(sizeof(*tp_c), GFP_KERNEL);
                if (tp_c == NULL) {
                        kfree(root_ht);
                        return -ENOBUFS;