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authorJohannes Berg <johannes.berg@intel.com>2015-01-17 00:09:00 +0300
committerDavid S. Miller <davem@davemloft.net>2015-01-18 09:03:45 +0300
commit053c095a82cf773075e83d7233b5cc19a1f73ece (patch)
treec787028efa9a73a182a0f338f87b6294cef4b8b9 /include/net
parentede58ef28e105de94475b2b69fa069c9a2ce6933 (diff)
downloadlinux-053c095a82cf773075e83d7233b5cc19a1f73ece.tar.xz
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.h4
-rw-r--r--include/net/netlink.h6
2 files changed, 3 insertions, 7 deletions
diff --git a/include/net/genetlink.h b/include/net/genetlink.h
index 84125088c309..f24aa83b80b6 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 d5869b90bfbb..e010ee8da41d 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;
}
/**