net: skbuff: reorder bytes 2 and 3 of the bitfield

BPF needs to know the offsets of fields it tries to access.
Zero-length fields are added to make offsetof() work.
This unfortunately partitions the bitfield (fields across
the zero-length members can't be coalesced).

Reorder bytes 2 and 3, BPF needs to know the offset of fields
previously in byte 3 and some fields in byte 2 should really
be optional.

The two bytes are always in the same cacheline so it should
not matter.

Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Link: https://lore.kernel.org/r/20230321014115.997841-3-kuba@kernel.org
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>

diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index 5a63878..36d31e7 100644 (file)
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -944,16 +944,6 @@ struct sk_buff {
        __u8                    ip_summed:2;
        __u8                    ooo_okay:1;
 
-       __u8                    l4_hash:1;
-       __u8                    sw_hash:1;
-       __u8                    wifi_acked_valid:1;
-       __u8                    wifi_acked:1;
-       __u8                    no_fcs:1;
-       /* Indicates the inner headers are valid in the skbuff. */
-       __u8                    encapsulation:1;
-       __u8                    encap_hdr_csum:1;
-       __u8                    csum_valid:1;
-
        /* private: */
        __u8                    __mono_tc_offset[0];
        /* public: */
@@ -966,6 +956,16 @@ struct sk_buff {
        __u8                    tc_skip_classify:1;
        __u8                    tc_at_ingress:1;        /* See TC_AT_INGRESS_MASK */
 #endif
+
+       __u8                    l4_hash:1;
+       __u8                    sw_hash:1;
+       __u8                    wifi_acked_valid:1;
+       __u8                    wifi_acked:1;
+       __u8                    no_fcs:1;
+       /* Indicates the inner headers are valid in the skbuff. */
+       __u8                    encapsulation:1;
+       __u8                    encap_hdr_csum:1;
+       __u8                    csum_valid:1;
 #ifdef CONFIG_IPV6_NDISC_NODETYPE
        __u8                    ndisc_nodetype:2;
 #endif