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>
diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c
index f7c8bbe..8975d95 100644
--- a/net/ipv6/addrconf.c
+++ b/net/ipv6/addrconf.c
@@ -489,7 +489,8 @@
nla_put_s32(skb, NETCONFA_PROXY_NEIGH, devconf->proxy_ndp) < 0)
goto nla_put_failure;
- return nlmsg_end(skb, nlh);
+ nlmsg_end(skb, nlh);
+ return 0;
nla_put_failure:
nlmsg_cancel(skb, nlh);
@@ -619,7 +620,7 @@
cb->nlh->nlmsg_seq,
RTM_NEWNETCONF,
NLM_F_MULTI,
- -1) <= 0) {
+ -1) < 0) {
rcu_read_unlock();
goto done;
}
@@ -635,7 +636,7 @@
NETLINK_CB(cb->skb).portid,
cb->nlh->nlmsg_seq,
RTM_NEWNETCONF, NLM_F_MULTI,
- -1) <= 0)
+ -1) < 0)
goto done;
else
h++;
@@ -646,7 +647,7 @@
NETLINK_CB(cb->skb).portid,
cb->nlh->nlmsg_seq,
RTM_NEWNETCONF, NLM_F_MULTI,
- -1) <= 0)
+ -1) < 0)
goto done;
else
h++;
@@ -4047,7 +4048,8 @@
if (nla_put_u32(skb, IFA_FLAGS, ifa->flags) < 0)
goto error;
- return nlmsg_end(skb, nlh);
+ nlmsg_end(skb, nlh);
+ return 0;
error:
nlmsg_cancel(skb, nlh);
@@ -4076,7 +4078,8 @@
return -EMSGSIZE;
}
- return nlmsg_end(skb, nlh);
+ nlmsg_end(skb, nlh);
+ return 0;
}
static int inet6_fill_ifacaddr(struct sk_buff *skb, struct ifacaddr6 *ifaca,
@@ -4101,7 +4104,8 @@
return -EMSGSIZE;
}
- return nlmsg_end(skb, nlh);
+ nlmsg_end(skb, nlh);
+ return 0;
}
enum addr_type_t {
@@ -4134,7 +4138,7 @@
cb->nlh->nlmsg_seq,
RTM_NEWADDR,
NLM_F_MULTI);
- if (err <= 0)
+ if (err < 0)
break;
nl_dump_check_consistent(cb, nlmsg_hdr(skb));
}
@@ -4151,7 +4155,7 @@
cb->nlh->nlmsg_seq,
RTM_GETMULTICAST,
NLM_F_MULTI);
- if (err <= 0)
+ if (err < 0)
break;
}
break;
@@ -4166,7 +4170,7 @@
cb->nlh->nlmsg_seq,
RTM_GETANYCAST,
NLM_F_MULTI);
- if (err <= 0)
+ if (err < 0)
break;
}
break;
@@ -4638,7 +4642,8 @@
goto nla_put_failure;
nla_nest_end(skb, protoinfo);
- return nlmsg_end(skb, nlh);
+ nlmsg_end(skb, nlh);
+ return 0;
nla_put_failure:
nlmsg_cancel(skb, nlh);
@@ -4670,7 +4675,7 @@
if (inet6_fill_ifinfo(skb, idev,
NETLINK_CB(cb->skb).portid,
cb->nlh->nlmsg_seq,
- RTM_NEWLINK, NLM_F_MULTI) <= 0)
+ RTM_NEWLINK, NLM_F_MULTI) < 0)
goto out;
cont:
idx++;
@@ -4747,7 +4752,8 @@
ci.valid_time = ntohl(pinfo->valid);
if (nla_put(skb, PREFIX_CACHEINFO, sizeof(ci), &ci))
goto nla_put_failure;
- return nlmsg_end(skb, nlh);
+ nlmsg_end(skb, nlh);
+ return 0;
nla_put_failure:
nlmsg_cancel(skb, nlh);
diff --git a/net/ipv6/addrlabel.c b/net/ipv6/addrlabel.c
index fd0dc47..e43e79d 100644
--- a/net/ipv6/addrlabel.c
+++ b/net/ipv6/addrlabel.c
@@ -490,7 +490,8 @@
return -EMSGSIZE;
}
- return nlmsg_end(skb, nlh);
+ nlmsg_end(skb, nlh);
+ return 0;
}
static int ip6addrlbl_dump(struct sk_buff *skb, struct netlink_callback *cb)
@@ -510,7 +511,7 @@
cb->nlh->nlmsg_seq,
RTM_NEWADDRLABEL,
NLM_F_MULTI);
- if (err <= 0)
+ if (err < 0)
break;
}
idx++;
diff --git a/net/ipv6/ip6_fib.c b/net/ipv6/ip6_fib.c
index 03c520a..53775ee 100644
--- a/net/ipv6/ip6_fib.c
+++ b/net/ipv6/ip6_fib.c
@@ -277,7 +277,6 @@
w->leaf = rt;
return 1;
}
- WARN_ON(res == 0);
}
w->leaf = NULL;
return 0;
diff --git a/net/ipv6/ip6mr.c b/net/ipv6/ip6mr.c
index 7226697..34b6826 100644
--- a/net/ipv6/ip6mr.c
+++ b/net/ipv6/ip6mr.c
@@ -2388,7 +2388,8 @@
if (err < 0 && err != -ENOENT)
goto nla_put_failure;
- return nlmsg_end(skb, nlh);
+ nlmsg_end(skb, nlh);
+ return 0;
nla_put_failure:
nlmsg_cancel(skb, nlh);
diff --git a/net/ipv6/route.c b/net/ipv6/route.c
index 34dcbb5..c60f157 100644
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -2725,7 +2725,8 @@
if (rtnl_put_cacheinfo(skb, &rt->dst, 0, expires, rt->dst.error) < 0)
goto nla_put_failure;
- return nlmsg_end(skb, nlh);
+ nlmsg_end(skb, nlh);
+ return 0;
nla_put_failure:
nlmsg_cancel(skb, nlh);