From 053c095a82cf773075e83d7233b5cc19a1f73ece Mon Sep 17 00:00:00 2001 From: Johannes Berg Date: Fri, 16 Jan 2015 22:09:00 +0100 Subject: 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 Signed-off-by: David S. Miller --- net/ieee802154/netlink.c | 12 ++---------- net/ieee802154/nl-mac.c | 3 ++- net/ieee802154/nl-phy.c | 3 ++- net/ieee802154/nl802154.c | 6 ++++-- 4 files changed, 10 insertions(+), 14 deletions(-) (limited to 'net/ieee802154') diff --git a/net/ieee802154/netlink.c b/net/ieee802154/netlink.c index fa1464762d0d..c8133c07ceee 100644 --- a/net/ieee802154/netlink.c +++ b/net/ieee802154/netlink.c @@ -63,13 +63,9 @@ int ieee802154_nl_mcast(struct sk_buff *msg, unsigned int group) struct nlmsghdr *nlh = nlmsg_hdr(msg); void *hdr = genlmsg_data(nlmsg_data(nlh)); - if (genlmsg_end(msg, hdr) < 0) - goto out; + genlmsg_end(msg, hdr); return genlmsg_multicast(&nl802154_family, msg, 0, group, GFP_ATOMIC); -out: - nlmsg_free(msg); - return -ENOBUFS; } struct sk_buff *ieee802154_nl_new_reply(struct genl_info *info, @@ -96,13 +92,9 @@ int ieee802154_nl_reply(struct sk_buff *msg, struct genl_info *info) struct nlmsghdr *nlh = nlmsg_hdr(msg); void *hdr = genlmsg_data(nlmsg_data(nlh)); - if (genlmsg_end(msg, hdr) < 0) - goto out; + genlmsg_end(msg, hdr); return genlmsg_reply(msg, info); -out: - nlmsg_free(msg); - return -ENOBUFS; } static const struct genl_ops ieee8021154_ops[] = { diff --git a/net/ieee802154/nl-mac.c b/net/ieee802154/nl-mac.c index 3c902e9516fb..9105265920fe 100644 --- a/net/ieee802154/nl-mac.c +++ b/net/ieee802154/nl-mac.c @@ -136,7 +136,8 @@ static int ieee802154_nl_fill_iface(struct sk_buff *msg, u32 portid, } wpan_phy_put(phy); - return genlmsg_end(msg, hdr); + genlmsg_end(msg, hdr); + return 0; nla_put_failure: wpan_phy_put(phy); diff --git a/net/ieee802154/nl-phy.c b/net/ieee802154/nl-phy.c index 7baf98b14611..1b9d25f6e898 100644 --- a/net/ieee802154/nl-phy.c +++ b/net/ieee802154/nl-phy.c @@ -65,7 +65,8 @@ static int ieee802154_nl_fill_phy(struct sk_buff *msg, u32 portid, goto nla_put_failure; mutex_unlock(&phy->pib_lock); kfree(buf); - return genlmsg_end(msg, hdr); + genlmsg_end(msg, hdr); + return 0; nla_put_failure: mutex_unlock(&phy->pib_lock); diff --git a/net/ieee802154/nl802154.c b/net/ieee802154/nl802154.c index a25b9bbd077b..a4daf91b8d0a 100644 --- a/net/ieee802154/nl802154.c +++ b/net/ieee802154/nl802154.c @@ -306,7 +306,8 @@ static int nl802154_send_wpan_phy(struct cfg802154_registered_device *rdev, goto nla_put_failure; finish: - return genlmsg_end(msg, hdr); + genlmsg_end(msg, hdr); + return 0; nla_put_failure: genlmsg_cancel(msg, hdr); @@ -489,7 +490,8 @@ nl802154_send_iface(struct sk_buff *msg, u32 portid, u32 seq, int flags, if (nla_put_u8(msg, NL802154_ATTR_LBT_MODE, wpan_dev->lbt)) goto nla_put_failure; - return genlmsg_end(msg, hdr); + genlmsg_end(msg, hdr); + return 0; nla_put_failure: genlmsg_cancel(msg, hdr); -- cgit v1.2.3