kernel_optimize_test/net/xfrm
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
..
Kconfig
Makefile
xfrm_algo.c net: xfrm: xfrm_algo: Remove unused function 2015-01-12 16:50:46 -05:00
xfrm_hash.c
xfrm_hash.h xfrm: hash prefixed policies based on preflen thresholds 2014-09-02 13:29:44 +02:00
xfrm_input.c xfrm: Introduce xfrm_input_afinfo to access the the callbacks properly 2014-03-14 07:28:07 +01:00
xfrm_ipcomp.c
xfrm_output.c net: make skb_gso_segment error handling more robust 2014-10-20 12:38:13 -04:00
xfrm_policy.c Merge branch 'master' of git://git.kernel.org/pub/scm/linux/kernel/git/klassert/ipsec-next 2014-12-08 21:30:21 -05:00
xfrm_proc.c net: clean up snmp stats code 2014-05-07 16:06:05 -04:00
xfrm_replay.c
xfrm_state.c xfrm: remove useless hash_resize_mutex locks 2014-08-29 11:40:03 +02:00
xfrm_sysctl.c
xfrm_user.c netlink: make nlmsg_end() and genlmsg_end() void 2015-01-18 01:03:45 -05:00