linux/net/decnet
Johannes Berg 053c095a82 netlink: make nlmsg_end() and genlmsg_end() void
Contrary to common expectations for an "int" return, these functions
return only a positive value -- if used correctly they cannot even
return 0 because the message header will necessarily be in the skb.

This makes the very common pattern of

  if (genlmsg_end(...) < 0) { ... }

be a whole bunch of dead code. Many places also simply do

  return nlmsg_end(...);

and the caller is expected to deal with it.

This also commonly (at least for me) causes errors, because it is very
common to write

  if (my_function(...))
    /* error condition */

and if my_function() does "return nlmsg_end()" this is of course wrong.

Additionally, there's not a single place in the kernel that actually
needs the message length returned, and if anyone needs it later then
it'll be very easy to just use skb->len there.

Remove this, and make the functions void. This removes a bunch of dead
code as described above. The patch adds lines because I did

-	return nlmsg_end(...);
+	nlmsg_end(...);
+	return 0;

I could have preserved all the function's return values by returning
skb->len, but instead I've audited all the places calling the affected
functions and found that none cared. A few places actually compared
the return value with <= 0 in dump functionality, but that could just
be changed to < 0 with no change in behaviour, so I opted for the more
efficient version.

One instance of the error I've made numerous times now is also present
in net/phonet/pn_netlink.c in the route_dumpit() function - it didn't
check for <0 or <=0 and thus broke out of the loop every single time.
I've preserved this since it will (I think) have caused the messages to
userspace to be formatted differently with just a single message for
every SKB returned to userspace. It's possible that this isn't needed
for the tools that actually use this, but I don't even know what they
are so couldn't test that changing this behaviour would be acceptable.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2015-01-18 01:03:45 -05:00
..
netfilter net: Use netlink_ns_capable to verify the permisions of netlink messages 2014-04-24 13:44:54 -04:00
af_decnet.c new helper: memcpy_to_msg() 2014-11-24 04:28:51 -05:00
dn_dev.c netlink: make nlmsg_end() and genlmsg_end() void 2015-01-18 01:03:45 -05:00
dn_fib.c net: tcp: add RTAX_CC_ALGO fib handling 2015-01-05 22:55:24 -05:00
dn_neigh.c neigh: remove dynamic neigh table registration support 2014-11-11 15:23:54 -05:00
dn_nsp_in.c net: Fix use after free by removing length arg from sk_data_ready callbacks. 2014-04-11 16:15:36 -04:00
dn_nsp_out.c decnet: use correct RCU API to deref sk_dst_cache field 2013-01-28 00:15:27 -05:00
dn_route.c netlink: make nlmsg_end() and genlmsg_end() void 2015-01-18 01:03:45 -05:00
dn_rules.c sections: fix section conflicts in net 2012-10-06 03:04:45 +09:00
dn_table.c netlink: make nlmsg_end() and genlmsg_end() void 2015-01-18 01:03:45 -05:00
dn_timer.c decnet: Use time_after_eq 2014-08-22 12:23:11 -07:00
Kconfig net/decnet: remove depends on CONFIG_EXPERIMENTAL 2013-01-11 11:39:34 -08:00
Makefile
README
sysctl_net_decnet.c net: Convert uses of typedef ctl_table to struct ctl_table 2013-06-13 02:36:09 -07:00
TODO

                       Linux DECnet Project
                      ======================

The documentation for this kernel subsystem is available in the
Documentation/networking subdirectory of this distribution and also
on line at http://www.chygwyn.com/DECnet/

Steve Whitehouse <SteveW@ACM.org>