page_pool: use __cacheline_group_{begin, end}_aligned()

Instead of doing __cacheline_group_begin() __aligned(), use the new
__cacheline_group_{begin,end}_aligned(), so that it will take care
of the group alignment itself.
Also replace open-coded `4 * sizeof(long)` in two places with
a definition.

Signed-off-by: Alexander Lobakin <[e-mail]>
Signed-off-by: Tony Nguyen <[e-mail]>

include/net/page_pool/types.h

···
 };
 #endif
 
+/* The whole frag API block must stay within one cacheline. On 32-bit systems,
+ * sizeof(long) == sizeof(int), so that the block size is ``3 * sizeof(long)``.
+ * On 64-bit systems, the actual size is ``2 * sizeof(long) + sizeof(int)``.
+ * The closest pow-2 to both of them is ``4 * sizeof(long)``, so just use that
+ * one for simplicity.
+ * Having it aligned to a cacheline boundary may be excessive and doesn't bring
+ * any good.
+ */
+#define PAGE_POOL_FRAG_GROUP_ALIGN	(4 * sizeof(long))
+
 struct page_pool {
 	struct page_pool_params_fast p;
 
···
 	bool system:1;			/* This is a global percpu pool */
 #endif
 
-	/* The following block must stay within one cacheline. On 32-bit
-	 * systems, sizeof(long) == sizeof(int), so that the block size is
-	 * ``3 * sizeof(long)``. On 64-bit systems, the actual size is
-	 * ``2 * sizeof(long) + sizeof(int)``. The closest pow-2 to both of
-	 * them is ``4 * sizeof(long)``, so just use that one for simplicity.
-	 * Having it aligned to a cacheline boundary may be excessive and
-	 * doesn't bring any good.
-	 */
-	__cacheline_group_begin(frag) __aligned(4 * sizeof(long));
+	__cacheline_group_begin_aligned(frag, PAGE_POOL_FRAG_GROUP_ALIGN);
 	long frag_users;
 	netmem_ref frag_page;
 	unsigned int frag_offset;
-	__cacheline_group_end(frag);
+	__cacheline_group_end_aligned(frag, PAGE_POOL_FRAG_GROUP_ALIGN);
 
 	struct delayed_work release_dw;
 	void (*disconnect)(void *pool);

net/core/page_pool.c

···
 	CACHELINE_ASSERT_GROUP_MEMBER(struct page_pool, frag, frag_users);
 	CACHELINE_ASSERT_GROUP_MEMBER(struct page_pool, frag, frag_page);
 	CACHELINE_ASSERT_GROUP_MEMBER(struct page_pool, frag, frag_offset);
-	CACHELINE_ASSERT_GROUP_SIZE(struct page_pool, frag, 4 * sizeof(long));
+	CACHELINE_ASSERT_GROUP_SIZE(struct page_pool, frag,
+				    PAGE_POOL_FRAG_GROUP_ALIGN);
 }
 
 static int page_pool_init(struct page_pool *pool,