netfilter: nft_bitwise: correct uapi header comment.

The comment documenting how bitwise expressions work includes a table
which summarizes the mask and xor arguments combined to express the
supported boolean operations.  However, the row for OR:

 mask    xor
 0       x

is incorrect.

  dreg = (sreg & 0) ^ x

is not equivalent to:

  dreg = sreg | x

What the code actually does is:

  dreg = (sreg & ~x) ^ x

Update the documentation to match.

Signed-off-by: Jeremy Sowden <jeremy@azazel.net>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

diff --git a/include/uapi/linux/netfilter/nf_tables.h b/include/uapi/linux/netfilter/nf_tables.h
index e237ecbdcd8ac3740cfaa714fcb6e3a1f340a317..dd46117679338b5cfb655bb65645eaaeec326631 100644 (file)
--- a/include/uapi/linux/netfilter/nf_tables.h
+++ b/include/uapi/linux/netfilter/nf_tables.h
@@ -501,7 +501,7 @@ enum nft_immediate_attributes {
  *
  *             mask    xor
  * NOT:                1       1
- * OR:         0       x
+ * OR:         ~x      x
  * XOR:                1       x
  * AND:                x       0
  */