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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 07:03:45 +0100 |
commit | 053c095a82cf773075e83d7233b5cc19a1f73ece (patch) | |
tree | c787028efa9a73a182a0f338f87b6294cef4b8b9 /kernel | |
parent | atm: remove deprecated use of pci api (diff) | |
download | linux-053c095a82cf773075e83d7233b5cc19a1f73ece.tar.xz linux-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 'kernel')
-rw-r--r-- | kernel/taskstats.c | 13 |
1 files changed, 2 insertions, 11 deletions
diff --git a/kernel/taskstats.c b/kernel/taskstats.c index 670fff88a961..21f82c29c914 100644 --- a/kernel/taskstats.c +++ b/kernel/taskstats.c @@ -111,13 +111,8 @@ static int send_reply(struct sk_buff *skb, struct genl_info *info) { struct genlmsghdr *genlhdr = nlmsg_data(nlmsg_hdr(skb)); void *reply = genlmsg_data(genlhdr); - int rc; - rc = genlmsg_end(skb, reply); - if (rc < 0) { - nlmsg_free(skb); - return rc; - } + genlmsg_end(skb, reply); return genlmsg_reply(skb, info); } @@ -134,11 +129,7 @@ static void send_cpu_listeners(struct sk_buff *skb, void *reply = genlmsg_data(genlhdr); int rc, delcount = 0; - rc = genlmsg_end(skb, reply); - if (rc < 0) { - nlmsg_free(skb); - return; - } + genlmsg_end(skb, reply); rc = 0; down_read(&listeners->sem); |