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author | Johannes Berg <johannes.berg@intel.com> | 2015-01-16 22:09:00 +0100 |
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committer | David S. Miller <davem@davemloft.net> | 2015-01-18 01:03:45 -0500 |
commit | 053c095a82cf773075e83d7233b5cc19a1f73ece (patch) | |
tree | c787028efa9a73a182a0f338f87b6294cef4b8b9 /net/netlabel/netlabel_cipso_v4.c | |
parent | ede58ef28e105de94475b2b69fa069c9a2ce6933 (diff) | |
download | lwn-053c095a82cf773075e83d7233b5cc19a1f73ece.tar.gz lwn-053c095a82cf773075e83d7233b5cc19a1f73ece.zip |
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>
Diffstat (limited to 'net/netlabel/netlabel_cipso_v4.c')
-rw-r--r-- | net/netlabel/netlabel_cipso_v4.c | 3 |
1 files changed, 2 insertions, 1 deletions
diff --git a/net/netlabel/netlabel_cipso_v4.c b/net/netlabel/netlabel_cipso_v4.c index c2f2a53a4879..179625353cac 100644 --- a/net/netlabel/netlabel_cipso_v4.c +++ b/net/netlabel/netlabel_cipso_v4.c @@ -641,7 +641,8 @@ static int netlbl_cipsov4_listall_cb(struct cipso_v4_doi *doi_def, void *arg) if (ret_val != 0) goto listall_cb_failure; - return genlmsg_end(cb_arg->skb, data); + genlmsg_end(cb_arg->skb, data); + return 0; listall_cb_failure: genlmsg_cancel(cb_arg->skb, data); |