[PATCH net-next] nfp: flower: refine the use of circular buffer

@@ -43,15 +43,14 @@ static int nfp_release_stats_entry(struct nfp_app *app, u32 stats_context_id)
 	struct circ_buf *ring;
 
 	ring = &priv->stats_ids.free_list;
-	/* Check if buffer is full. */
-	if (!CIRC_SPACE(ring->head, ring->tail,
-			priv->stats_ring_size * NFP_FL_STATS_ELEM_RS -
-			NFP_FL_STATS_ELEM_RS + 1))
+	/* Check if buffer is full, stats_ring_size must be power of 2 */
+	if (!CIRC_SPACE(ring->head, ring->tail, priv->stats_ring_size))
 		return -ENOBUFS;
 
-	memcpy(&ring->buf[ring->head], &stats_context_id, NFP_FL_STATS_ELEM_RS);
-	ring->head = (ring->head + NFP_FL_STATS_ELEM_RS) %
-		     (priv->stats_ring_size * NFP_FL_STATS_ELEM_RS);
+	/* Each increment of head represents size of NFP_FL_STATS_ELEM_RS */
+	memcpy(&ring->buf[ring->head * NFP_FL_STATS_ELEM_RS],
+	       &stats_context_id, NFP_FL_STATS_ELEM_RS);
+	ring->head = (ring->head + 1) & (priv->stats_ring_size - 1);
 
 	return 0;
 }

@@ -86,11 +85,14 @@ static int nfp_get_stats_entry(struct nfp_app *app, u32 *stats_context_id)
 		return -ENOENT;
 	}
 
-	memcpy(&temp_stats_id, &ring->buf[ring->tail], NFP_FL_STATS_ELEM_RS);
+	/* Each increment of tail represents size of NFP_FL_STATS_ELEM_RS */
+	memcpy(&temp_stats_id, &ring->buf[ring->tail * NFP_FL_STATS_ELEM_RS],
+	       NFP_FL_STATS_ELEM_RS);
 	*stats_context_id = temp_stats_id;
-	memcpy(&ring->buf[ring->tail], &freed_stats_id, NFP_FL_STATS_ELEM_RS);
-	ring->tail = (ring->tail + NFP_FL_STATS_ELEM_RS) %
-		     (priv->stats_ring_size * NFP_FL_STATS_ELEM_RS);
+	memcpy(&ring->buf[ring->tail * NFP_FL_STATS_ELEM_RS], &freed_stats_id,
+	       NFP_FL_STATS_ELEM_RS);
+	/* stats_ring_size must be power of 2 */
+	ring->tail = (ring->tail + 1) & (priv->stats_ring_size - 1);
 
 	return 0;
 }

@@ -138,13 +140,18 @@ static int nfp_release_mask_id(struct nfp_app *app, u8 mask_id)
 	struct circ_buf *ring;
 
 	ring = &priv->mask_ids.mask_id_free_list;
-	/* Checking if buffer is full. */
+	/* Checking if buffer is full,
+	 * NFP_FLOWER_MASK_ENTRY_RS must be power of 2
+	 */
 	if (CIRC_SPACE(ring->head, ring->tail, NFP_FLOWER_MASK_ENTRY_RS) == 0)
 		return -ENOBUFS;
 
-	memcpy(&ring->buf[ring->head], &mask_id, NFP_FLOWER_MASK_ELEMENT_RS);
-	ring->head = (ring->head + NFP_FLOWER_MASK_ELEMENT_RS) %
-		     (NFP_FLOWER_MASK_ENTRY_RS * NFP_FLOWER_MASK_ELEMENT_RS);
+	/* Each increment of head represents size of
+	 * NFP_FLOWER_MASK_ELEMENT_RS
+	 */
+	memcpy(&ring->buf[ring->head * NFP_FLOWER_MASK_ELEMENT_RS], &mask_id,
+	       NFP_FLOWER_MASK_ELEMENT_RS);
+	ring->head = (ring->head + 1) & (NFP_FLOWER_MASK_ENTRY_RS - 1);
 
 	priv->mask_ids.last_used[mask_id] = ktime_get();
 

@@ -171,7 +178,11 @@ static int nfp_mask_alloc(struct nfp_app *app, u8 *mask_id)
 	if (ring->head == ring->tail)
 		goto err_not_found;
 
-	memcpy(&temp_id, &ring->buf[ring->tail], NFP_FLOWER_MASK_ELEMENT_RS);
+	/* Each increment of tail represents size of
+	 * NFP_FLOWER_MASK_ELEMENT_RS
+	 */
+	memcpy(&temp_id, &ring->buf[ring->tail * NFP_FLOWER_MASK_ELEMENT_RS],
+	       NFP_FLOWER_MASK_ELEMENT_RS);
 	*mask_id = temp_id;
 
 	reuse_timeout = ktime_add_ns(priv->mask_ids.last_used[*mask_id],

@@ -180,9 +191,10 @@ static int nfp_mask_alloc(struct nfp_app *app, u8 *mask_id)
 	if (ktime_before(ktime_get(), reuse_timeout))
 		goto err_not_found;
 
-	memcpy(&ring->buf[ring->tail], &freed_id, NFP_FLOWER_MASK_ELEMENT_RS);
-	ring->tail = (ring->tail + NFP_FLOWER_MASK_ELEMENT_RS) %
-		     (NFP_FLOWER_MASK_ENTRY_RS * NFP_FLOWER_MASK_ELEMENT_RS);
+	memcpy(&ring->buf[ring->tail * NFP_FLOWER_MASK_ELEMENT_RS], &freed_id,
+	       NFP_FLOWER_MASK_ELEMENT_RS);
+	/* NFP_FLOWER_MASK_ENTRY_RS must be power of 2 */
+	ring->tail = (ring->tail + 1) & (NFP_FLOWER_MASK_ENTRY_RS - 1);
 
 	return 0;