Subject: [PATCH 04/10 net-next] page_pool: Add API to update numa node and flush page caches

From: Jonathan Lemon <[email-masked]>
Date: Wed, 16 Oct 2019 15:50:22 -0700

From: Saeed Mahameed <[email-masked]>

Add page_pool_update_nid() to be called from drivers when they detect
numa node changes.

It will do:
1) Flush the pool's page cache and ptr_ring.
2) Update page pool nid value to start allocating from the new numa
node.

Signed-off-by: Saeed Mahameed <[email-masked]>
Signed-off-by: Jonathan Lemon <[email-masked]>
---
 include/net/page_pool.h | 10 ++++++++++
 net/core/page_pool.c    | 16 +++++++++++-----
 2 files changed, 21 insertions(+), 5 deletions(-)

diff --git a/include/net/page_pool.h b/include/net/page_pool.h
index 2cbcdbdec254..fb13cf6055ff 100644
--- a/include/net/page_pool.h
+++ b/include/net/page_pool.h
@@ -226,4 +226,14 @@ static inline bool page_pool_put(struct page_pool *pool)
 	return refcount_dec_and_test(&pool->user_cnt);
 }
 
+/* Only safe from napi context or when user guarantees it is thread safe */
+void __page_pool_flush(struct page_pool *pool);
+static inline void page_pool_update_nid(struct page_pool *pool, int new_nid)
+{
+	if (unlikely(pool->p.nid != new_nid)) {
+		/* TODO: Add statistics/trace */
+		__page_pool_flush(pool);
+		pool->p.nid = new_nid;
+	}
+}
 #endif /* _NET_PAGE_POOL_H */
diff --git a/net/core/page_pool.c b/net/core/page_pool.c
index 5bc65587f1c4..678cf85f273a 100644
--- a/net/core/page_pool.c
+++ b/net/core/page_pool.c
@@ -373,16 +373,13 @@ void __page_pool_free(struct page_pool *pool)
 }
 EXPORT_SYMBOL(__page_pool_free);
 
-/* Request to shutdown: release pages cached by page_pool, and check
- * for in-flight pages
- */
-bool __page_pool_request_shutdown(struct page_pool *pool)
+void __page_pool_flush(struct page_pool *pool)
 {
 	struct page *page;
 
 	/* Empty alloc cache, assume caller made sure this is
 	 * no-longer in use, and page_pool_alloc_pages() cannot be
-	 * call concurrently.
+	 * called concurrently.
 	 */
 	while (pool->alloc.count) {
 		page = pool->alloc.cache[--pool->alloc.count];
@@ -393,6 +390,15 @@ bool __page_pool_request_shutdown(struct page_pool *pool)
 	 * be in-flight.
 	 */
 	__page_pool_empty_ring(pool);
+}
+EXPORT_SYMBOL(__page_pool_flush);
+
+/* Request to shutdown: release pages cached by page_pool, and check
+ * for in-flight pages
+ */
+bool __page_pool_request_shutdown(struct page_pool *pool)
+{
+	__page_pool_flush(pool);
 
 	return __page_pool_safe_to_destroy(pool);
 }
-- 
2.17.1