net: add helper to pre-check if PP for an Rx queue will be unreadable

mlx5 pokes into the rxq state to check if the queue has a memory
provider, and therefore whether it may produce unreadable mem.
Add a helper for doing this in the page pool API. fbnic will want
a similar thing (tho, for a slightly different reason).

Reviewed-by: Mina Almasry <almasrymina@google.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Link: https://patch.msgid.link/20250901211214.1027927-11-kuba@kernel.org
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

2 files changed, 14 insertions, 0 deletions

diff --git a/include/net/netdev_queues.h b/include/net/netdev_queues.h
index b9d02bc65c97..cd00e0406cf4 100644
--- a/include/net/netdev_queues.h
+++ b/include/net/netdev_queues.h
@@ -151,6 +151,8 @@ struct netdev_queue_mgmt_ops {
 							 int idx);
 };
 
+bool netif_rxq_has_unreadable_mp(struct net_device *dev, int idx);
+
 /**
  * DOC: Lockless queue stopping / waking helpers.
  *
diff --git a/include/net/page_pool/helpers.h b/include/net/page_pool/helpers.h
index aa3719f28216..3247026e096a 100644
--- a/include/net/page_pool/helpers.h
+++ b/include/net/page_pool/helpers.h
@@ -505,6 +505,18 @@ static inline void page_pool_nid_changed(struct page_pool *pool, int new_nid)
 		page_pool_update_nid(pool, new_nid);
 }
 
+/**
+ * page_pool_is_unreadable() - will allocated buffers be unreadable for the CPU
+ * @pool: queried page pool
+ *
+ * Check if page pool will return buffers which are unreadable to the CPU /
+ * kernel. This will only be the case if user space bound a memory provider (mp)
+ * which returns unreadable memory to the queue served by the page pool.
+ * If %PP_FLAG_ALLOW_UNREADABLE_NETMEM was set but there is no mp bound
+ * this helper will return false. See also netif_rxq_has_unreadable_mp().
+ *
+ * Return: true if memory allocated by the page pool may be unreadable
+ */
 static inline bool page_pool_is_unreadable(struct page_pool *pool)
 {
 	return !!pool->mp_ops;