page_pool: constify some read-only function arguments

There are several functions taking pointers to data they don't modify.
This includes statistics fetching, page and page_pool parameters, etc.
Constify the pointers, so that call sites will be able to pass const
pointers as well.
No functional changes, no visible changes in functions sizes.
Reviewed-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>
Signed-off-by: Alexander Lobakin <aleksander.lobakin@intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>

include/net/page_pool/helpers.h

@@ -58,7 +58,7 @@
 /* Deprecated driver-facing API, use netlink instead */
 int page_pool_ethtool_stats_get_count(void);
 u8 *page_pool_ethtool_stats_get_strings(u8 *data);
-u64 *page_pool_ethtool_stats_get(u64 *data, void *stats);
+u64 *page_pool_ethtool_stats_get(u64 *data, const void *stats);
 
 bool page_pool_get_stats(const struct page_pool *pool,
 			 struct page_pool_stats *stats);
@@ -73,7 +73,7 @@ static inline u8 *page_pool_ethtool_stats_get_strings(u8 *data)
 	return data;
 }
 
-static inline u64 *page_pool_ethtool_stats_get(u64 *data, void *stats)
+static inline u64 *page_pool_ethtool_stats_get(u64 *data, const void *stats)
 {
 	return data;
 }
@@ -204,8 +204,8 @@ static inline void *page_pool_dev_alloc_va(struct page_pool *pool,
  * Get the stored dma direction. A driver might decide to store this locally
  * and avoid the extra cache line from page_pool to determine the direction.
  */
-static
-inline enum dma_data_direction page_pool_get_dma_dir(struct page_pool *pool)
+static inline enum dma_data_direction
+page_pool_get_dma_dir(const struct page_pool *pool)
 {
 	return pool->p.dma_dir;
 }
@@ -370,7 +370,7 @@ static inline void page_pool_free_va(struct page_pool *pool, void *va,
  * Fetch the DMA address of the page. The page pool to which the page belongs
  * must had been created with PP_FLAG_DMA_MAP.
  */
-static inline dma_addr_t page_pool_get_dma_addr(struct page *page)
+static inline dma_addr_t page_pool_get_dma_addr(const struct page *page)
 {
 	dma_addr_t ret = page->dma_addr;
 

include/net/page_pool/types.h

@@ -213,7 +213,7 @@ struct xdp_mem_info;
 #ifdef CONFIG_PAGE_POOL
 void page_pool_destroy(struct page_pool *pool);
 void page_pool_use_xdp_mem(struct page_pool *pool, void (*disconnect)(void *),
-			   struct xdp_mem_info *mem);
+			   const struct xdp_mem_info *mem);
 void page_pool_put_page_bulk(struct page_pool *pool, void **data,
 			     int count);
 #else
@@ -223,7 +223,7 @@ static inline void page_pool_destroy(struct page_pool *pool)
 
 static inline void page_pool_use_xdp_mem(struct page_pool *pool,
 					 void (*disconnect)(void *),
-					 struct xdp_mem_info *mem)
+					 const struct xdp_mem_info *mem)
 {
 }
 

net/core/page_pool.c

@@ -123,9 +123,9 @@ int page_pool_ethtool_stats_get_count(void)
 }
 EXPORT_SYMBOL(page_pool_ethtool_stats_get_count);
 
-u64 *page_pool_ethtool_stats_get(u64 *data, void *stats)
+u64 *page_pool_ethtool_stats_get(u64 *data, const void *stats)
 {
-	struct page_pool_stats *pool_stats = stats;
+	const struct page_pool_stats *pool_stats = stats;
 
 	*data++ = pool_stats->alloc_stats.fast;
 	*data++ = pool_stats->alloc_stats.slow;
@@ -383,8 +383,8 @@ static struct page *__page_pool_get_cached(struct page_pool *pool)
 	return page;
 }
 
-static void page_pool_dma_sync_for_device(struct page_pool *pool,
-					  struct page *page,
+static void page_pool_dma_sync_for_device(const struct page_pool *pool,
+					  const struct page *page,
 					  unsigned int dma_sync_size)
 {
 	dma_addr_t dma_addr = page_pool_get_dma_addr(page);
@@ -987,7 +987,7 @@ static void page_pool_release_retry(struct work_struct *wq)
 }
 
 void page_pool_use_xdp_mem(struct page_pool *pool, void (*disconnect)(void *),
-			   struct xdp_mem_info *mem)
+			   const struct xdp_mem_info *mem)
 {
 	refcount_inc(&pool->user_cnt);
 	pool->disconnect = disconnect;