benchdnn: brgemm: ukernel: fix f16 crashes with odd K

tests/benchdnn/brgemm/brgemm.cpp

@@ -274,6 +274,7 @@ struct kernel_args_t {
 #else
         brgemm_(nullptr)
         , brgemm_pack_B_(nullptr)
+        , need_pack_(0)
 #endif
         , scratchpad_size_(0)
         , generate_skip_accumulation_(false)
@@ -291,6 +292,7 @@ struct kernel_args_t {
 #else
     dnnl_brgemm_t brgemm_;
     dnnl_brgemm_pack_B_t brgemm_pack_B_;
+    int need_pack_; // `int` to match C API
 #endif
     size_t scratchpad_size_;
     bool generate_skip_accumulation_;
@@ -407,12 +409,11 @@ int init_kernel(kernel_args_t &kernel_args) {
     SAFE(check_dnnl_status(st, prb, res), WARN);
     if (res->state == SKIPPED) return OK;
 
-    int need_pack = 0;
-    st = dnnl_brgemm_pack_B_need_pack(brgemm_pack_B, &need_pack);
+    st = dnnl_brgemm_pack_B_need_pack(brgemm_pack_B, &kernel_args.need_pack_);
     SAFE(check_dnnl_status(st, prb, res), WARN);
     if (res->state == SKIPPED) return OK;
 
-    if (need_pack) {
+    if (kernel_args.need_pack_) {
         st = dnnl_brgemm_pack_B_generate(brgemm_pack_B);
         SAFE(check_dnnl_status(st, prb, res), WARN);
         if (res->state == SKIPPED) return OK;
@@ -660,7 +661,8 @@ void init_memory_args(
 
     // Needed to have enough memory after packing routine.
     // TODO: generalize special f16 case.
-    const int dt_multiplier = prb->wei_dt() == dnnl_f16
+    const int dt_multiplier
+            = prb->wei_dt() == dnnl_f16 && !kernel_args.need_pack_
             ? 1
             : 4 / dnnl_data_type_size(prb->wei_dt());
     const dnnl_dim_t k_rounded = dt_multiplier * div_up(prb->k, dt_multiplier);
@@ -1124,10 +1126,7 @@ int doit(const prb_t *prb, res_t *res) {
             ? (char *)mem_map.at(DNNL_ARG_SCRATCHPAD)
             : nullptr;
 
-    int need_pack = 0;
-    DNN_SAFE(dnnl_brgemm_pack_B_need_pack(brgemm_pack_B, &need_pack), WARN);
-
-    if (need_pack) {
+    if (kernel_args.need_pack_) {
         auto st = dnnl_brgemm_pack_B_execute(
                 brgemm_pack_B, wei_ptr, wei_packed_ptr);
         SAFE(check_dnnl_status(st, prb, res), WARN);