classify: use 32 bits hash
classify hash used to be stored as u64 in buffer metadata, use 32 bits
instead:
- on almost all our supported arch (x86 and arm64) we use crc32c
intrinsics to compute the final hash: we really get a 32-bits hash
- the hash itself is used to compute a 32-bits bucket index by masking
upper bits: we always discard the higher 32-bits
- this allows to increase the l2 classify buffer metadata padding such
as it does not overlap with the ip fib_index metadata anymore. This
overlap is an issue when using the 'set metadata' action in the ip
ACL node which updates both fields
Type: fix
Change-Id: I5d35bdae97b96c3cae534e859b63950fb500ff50
Signed-off-by: Benoît Ganne <bganne@cisco.com>
diff --git a/src/vnet/buffer.h b/src/vnet/buffer.h
index 2f25245..144f62a 100644
--- a/src/vnet/buffer.h
+++ b/src/vnet/buffer.h
@@ -320,13 +320,13 @@
/* L2 classify */
struct
{
- struct opaque_l2 pad;
+ u32 pad[4]; /* do not overlay w/ ip.fib_index nor l2 */
union
{
u32 table_index;
u32 opaque_index;
};
- u64 hash;
+ u32 hash;
} l2_classify;
/* vnet policer */