xsk: Expose min chunk size to drivers

Drivers should be aware of the range of valid UMEM chunk sizes to be
able to allocate their internal structures of an appropriate size. It
will be used by mlx5e in the following patches.
Signed-off-by: Maxim Mikityanskiy <maximmi@nvidia.com>
Reviewed-by: Tariq Toukan <tariqt@nvidia.com>
CC: "Björn Töpel" <bjorn@kernel.org>
CC: Magnus Karlsson <magnus.karlsson@intel.com>
CC: Maciej Fijalkowski <maciej.fijalkowski@intel.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

include/net/xdp_sock_drv.h

@@ -9,6 +9,9 @@
 #include <net/xdp_sock.h>
 #include <net/xsk_buff_pool.h>
 
+#define XDP_UMEM_MIN_CHUNK_SHIFT 11
+#define XDP_UMEM_MIN_CHUNK_SIZE (1 << XDP_UMEM_MIN_CHUNK_SHIFT)
+
 #ifdef CONFIG_XDP_SOCKETS
 
 void xsk_tx_completed(struct xsk_buff_pool *pool, u32 nb_entries);

net/xdp/xdp_umem.c

@@ -19,8 +19,6 @@
 #include "xdp_umem.h"
 #include "xsk_queue.h"
 
-#define XDP_UMEM_MIN_CHUNK_SIZE 2048
-
 static DEFINE_IDA(umem_ida);
 
 static void xdp_umem_unpin_pages(struct xdp_umem *umem)