Patch "xsk: Add cb area to struct xdp_buff_xsk" has been added to the 5.15-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    xsk: Add cb area to struct xdp_buff_xsk

to the 5.15-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     xsk-add-cb-area-to-struct-xdp_buff_xsk.patch
and it can be found in the queue-5.15 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit 65bf169438f4b555b96d411bdc60832ff3c33414
Author: Toke Høiland-Jørgensen <toke@xxxxxxxxxx>
Date:   Thu Jan 19 14:15:33 2023 -0800

    xsk: Add cb area to struct xdp_buff_xsk
    
    [ Upstream commit 94ecc5ca4dbf1f01bae6e32f5cd88c0fc5dc3cc9 ]
    
    Add an area after the xdp_buff in struct xdp_buff_xsk that drivers can use
    to stash extra information to use in metadata kfuncs. The maximum size of
    24 bytes means the full xdp_buff_xsk structure will take up exactly two
    cache lines (with the cb field spanning both). Also add a macro drivers can
    use to check their own wrapping structs against the available size.
    
    Cc: John Fastabend <john.fastabend@xxxxxxxxx>
    Cc: David Ahern <dsahern@xxxxxxxxx>
    Cc: Martin KaFai Lau <martin.lau@xxxxxxxxx>
    Cc: Jakub Kicinski <kuba@xxxxxxxxxx>
    Cc: Willem de Bruijn <willemb@xxxxxxxxxx>
    Cc: Jesper Dangaard Brouer <brouer@xxxxxxxxxx>
    Cc: Anatoly Burakov <anatoly.burakov@xxxxxxxxx>
    Cc: Alexander Lobakin <alexandr.lobakin@xxxxxxxxx>
    Cc: Magnus Karlsson <magnus.karlsson@xxxxxxxxx>
    Cc: Maryam Tahhan <mtahhan@xxxxxxxxxx>
    Cc: xdp-hints@xxxxxxxxxxxxxxx
    Cc: netdev@xxxxxxxxxxxxxxx
    Suggested-by: Jakub Kicinski <kuba@xxxxxxxxxx>
    Signed-off-by: Toke Høiland-Jørgensen <toke@xxxxxxxxxx>
    Signed-off-by: Stanislav Fomichev <sdf@xxxxxxxxxx>
    Link: https://lore.kernel.org/r/20230119221536.3349901-15-sdf@xxxxxxxxxx
    Signed-off-by: Martin KaFai Lau <martin.lau@xxxxxxxxxx>
    Stable-dep-of: 3ce29c17dc84 ("igc: read before write to SRRCTL register")
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/include/net/xsk_buff_pool.h b/include/net/xsk_buff_pool.h
index ebd1f43578d65..14db77ff5fca5 100644
--- a/include/net/xsk_buff_pool.h
+++ b/include/net/xsk_buff_pool.h
@@ -18,8 +18,11 @@ struct xdp_sock;
 struct device;
 struct page;
 
+#define XSK_PRIV_MAX 24
+
 struct xdp_buff_xsk {
 	struct xdp_buff xdp;
+	u8 cb[XSK_PRIV_MAX];
 	dma_addr_t dma;
 	dma_addr_t frame_dma;
 	struct xsk_buff_pool *pool;
@@ -28,6 +31,8 @@ struct xdp_buff_xsk {
 	struct list_head free_list_node;
 };
 
+#define XSK_CHECK_PRIV_TYPE(t) BUILD_BUG_ON(sizeof(t) > offsetofend(struct xdp_buff_xsk, cb))
+
 struct xsk_dma_map {
 	dma_addr_t *dma_pages;
 	struct device *dev;