linux/net/ieee802154
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
..
6lowpan ieee802154: 6lowpan: fix Makefile entry 2015-01-08 15:48:06 +01:00
core.c ieee802154: add wpan_phy dump support 2014-11-09 19:50:29 +01:00
core.h ieee802154: add wpan_phy dump support 2014-11-09 19:50:29 +01:00
header_ops.c ieee802154: move ieee802154 header 2014-10-25 21:39:57 +02:00
ieee802154.h ieee802154: add nl802154 framework 2014-11-09 19:50:29 +01:00
Kconfig ieee802154: create 6lowpan sub-directory 2015-01-08 07:25:59 +01:00
Makefile ieee802154: 6lowpan: fix Makefile entry 2015-01-08 15:48:06 +01:00
netlink.c netlink: make nlmsg_end() and genlmsg_end() void 2015-01-18 01:03:45 -05:00
nl-mac.c netlink: make nlmsg_end() and genlmsg_end() void 2015-01-18 01:03:45 -05:00
nl-phy.c netlink: make nlmsg_end() and genlmsg_end() void 2015-01-18 01:03:45 -05:00
nl802154.c netlink: make nlmsg_end() and genlmsg_end() void 2015-01-18 01:03:45 -05:00
nl802154.h ieee802154: add nl802154 framework 2014-11-09 19:50:29 +01:00
nl_policy.c ieee802154: mac802154: remove FSF address 2014-10-25 08:07:30 +02:00
rdev-ops.h nl802154: introduce support for cca settings 2014-12-19 00:19:23 +01:00
socket.c ieee802154: rename af_ieee802154.c to socket.c 2015-01-03 01:49:24 +01:00
sysfs.c ieee802154: rework cca setting 2014-12-19 00:19:23 +01:00
sysfs.h ieee802154: introduce sysfs file 2014-10-28 23:19:09 +01:00