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author | Johannes Berg <johannes.berg@intel.com> | 2015-01-16 22:09:00 +0100 |
---|---|---|
committer | David S. Miller <davem@davemloft.net> | 2015-01-18 01:03:45 -0500 |
commit | 053c095a82cf773075e83d7233b5cc19a1f73ece (patch) | |
tree | c787028efa9a73a182a0f338f87b6294cef4b8b9 /include/net | |
parent | ede58ef28e105de94475b2b69fa069c9a2ce6933 (diff) | |
download | op-kernel-dev-053c095a82cf773075e83d7233b5cc19a1f73ece.zip op-kernel-dev-053c095a82cf773075e83d7233b5cc19a1f73ece.tar.gz |
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 'include/net')
-rw-r--r-- | include/net/genetlink.h | 4 | ||||
-rw-r--r-- | include/net/netlink.h | 6 |
2 files changed, 3 insertions, 7 deletions
diff --git a/include/net/genetlink.h b/include/net/genetlink.h index 8412508..f24aa83 100644 --- a/include/net/genetlink.h +++ b/include/net/genetlink.h @@ -245,9 +245,9 @@ static inline void *genlmsg_put_reply(struct sk_buff *skb, * @skb: socket buffer the message is stored in * @hdr: user specific header */ -static inline int genlmsg_end(struct sk_buff *skb, void *hdr) +static inline void genlmsg_end(struct sk_buff *skb, void *hdr) { - return nlmsg_end(skb, hdr - GENL_HDRLEN - NLMSG_HDRLEN); + nlmsg_end(skb, hdr - GENL_HDRLEN - NLMSG_HDRLEN); } /** diff --git a/include/net/netlink.h b/include/net/netlink.h index d5869b9..e010ee8 100644 --- a/include/net/netlink.h +++ b/include/net/netlink.h @@ -490,14 +490,10 @@ static inline struct sk_buff *nlmsg_new(size_t payload, gfp_t flags) * Corrects the netlink message header to include the appeneded * attributes. Only necessary if attributes have been added to * the message. - * - * Returns the total data length of the skb. */ -static inline int nlmsg_end(struct sk_buff *skb, struct nlmsghdr *nlh) +static inline void nlmsg_end(struct sk_buff *skb, struct nlmsghdr *nlh) { nlh->nlmsg_len = skb_tail_pointer(skb) - (unsigned char *)nlh; - - return skb->len; } /** |