netlink: clarify attribute length check documentation
authorJohannes Berg <johannes.berg@intel.com>
Thu, 3 Nov 2011 00:10:05 +0000 (00:10 +0000)
committerDavid S. Miller <davem@davemloft.net>
Fri, 4 Nov 2011 21:48:23 +0000 (17:48 -0400)
The documentation for how the length of attributes
is checked is wrong ("Exact length" isn't true, the
policy checks are for "minimum length") and a bit
misleading. Make it more complete and explain what
really happens.

Cc: Thomas Graf <tgraf@suug.ch>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
include/net/netlink.h

index 98c185441bee0c2bf8b36caeb5637b13878cfaff..cb1f3504687fb74df065191ce65add598f063dac 100644 (file)
@@ -192,8 +192,15 @@ enum {
  *    NLA_NUL_STRING       Maximum length of string (excluding NUL)
  *    NLA_FLAG             Unused
  *    NLA_BINARY           Maximum length of attribute payload
- *    NLA_NESTED_COMPAT    Exact length of structure payload
- *    All other            Exact length of attribute payload
+ *    NLA_NESTED           Don't use `len' field -- length verification is
+ *                         done by checking len of nested header (or empty)
+ *    NLA_NESTED_COMPAT    Minimum length of structure payload
+ *    NLA_U8, NLA_U16,
+ *    NLA_U32, NLA_U64,
+ *    NLA_MSECS            Leaving the length field zero will verify the
+ *                         given type fits, using it verifies minimum length
+ *                         just like "All other"
+ *    All other            Minimum length of attribute payload
  *
  * Example:
  * static const struct nla_policy my_policy[ATTR_MAX+1] = {