net/mlx5e: SHAMPO, Specialize mlx5e_fill_skb_data()

mlx5e_fill_skb_data() used to have multiple callers. But after the XDP
multibuf refactoring from commit 2cb0e27d ("net/mlx5e: RX, Prepare
non-linear striding RQ for XDP multi-buffer support") the SHAMPO code
path is the only caller.

Take advantage of this and specialize the function:
- Drop the redundant check.
- Assume that data_bcnt is > 0. This is needed in a downstream patch.

Rename the function as well to make things clear.
Signed-off-by: Dragos Tatulea <dtatulea@nvidia.com>
Suggested-by: Tariq Toukan <tariqt@nvidia.com>
Signed-off-by: Tariq Toukan <tariqt@nvidia.com>
Link: https://lore.kernel.org/r/20240603212219.1037656-8-tariqt@nvidia.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>

drivers/net/ethernet/mellanox/mlx5/core/en_rx.c

@@ -1948,21 +1948,16 @@ const struct mlx5e_rx_handlers mlx5e_rx_handlers_rep = {
 #endif
 
 static void
-mlx5e_fill_skb_data(struct sk_buff *skb, struct mlx5e_rq *rq,
-		    struct mlx5e_frag_page *frag_page,
-		    u32 data_bcnt, u32 data_offset)
+mlx5e_shampo_fill_skb_data(struct sk_buff *skb, struct mlx5e_rq *rq,
+			   struct mlx5e_frag_page *frag_page,
+			   u32 data_bcnt, u32 data_offset)
 {
 	net_prefetchw(skb->data);
 
-	while (data_bcnt) {
+	do {
 		/* Non-linear mode, hence non-XSK, which always uses PAGE_SIZE. */
 		u32 pg_consumed_bytes = min_t(u32, PAGE_SIZE - data_offset, data_bcnt);
-		unsigned int truesize;
-
-		if (test_bit(MLX5E_RQ_STATE_SHAMPO, &rq->state))
-			truesize = pg_consumed_bytes;
-		else
-			truesize = ALIGN(pg_consumed_bytes, BIT(rq->mpwqe.log_stride_sz));
+		unsigned int truesize = pg_consumed_bytes;
 
 		frag_page->frags++;
 		mlx5e_add_skb_frag(rq, skb, frag_page->page, data_offset,
@@ -1971,7 +1966,7 @@ mlx5e_fill_skb_data(struct sk_buff *skb, struct mlx5e_rq *rq,
 		data_bcnt -= pg_consumed_bytes;
 		data_offset = 0;
 		frag_page++;
-	}
+	} while (data_bcnt);
 }
 
 static struct sk_buff *
@@ -2330,10 +2325,12 @@ static void mlx5e_handle_rx_cqe_mpwrq_shampo(struct mlx5e_rq *rq, struct mlx5_cq
 	}
 
 	if (likely(head_size)) {
-		struct mlx5e_frag_page *frag_page;
+		if (data_bcnt) {
+			struct mlx5e_frag_page *frag_page;
 
-		frag_page = &wi->alloc_units.frag_pages[page_idx];
-		mlx5e_fill_skb_data(*skb, rq, frag_page, data_bcnt, data_offset);
+			frag_page = &wi->alloc_units.frag_pages[page_idx];
+			mlx5e_shampo_fill_skb_data(*skb, rq, frag_page, data_bcnt, data_offset);
+		}
 	}
 
 	mlx5e_shampo_complete_rx_cqe(rq, cqe, cqe_bcnt, *skb);