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/netlabel/netlabel_cipso_v4.c | 3 ++- net/netlabel/netlabel_mgmt.c | 6 ++++-- net/netlabel/netlabel_unlabeled.c | 3 ++- 3 files changed, 8 insertions(+), 4 deletions(-) (limited to 'net/netlabel') 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); diff --git a/net/netlabel/netlabel_mgmt.c b/net/netlabel/netlabel_mgmt.c index e66e977ef2fa..8b3b789c43c2 100644 --- a/net/netlabel/netlabel_mgmt.c +++ b/net/netlabel/netlabel_mgmt.c @@ -456,7 +456,8 @@ static int netlbl_mgmt_listall_cb(struct netlbl_dom_map *entry, void *arg) goto listall_cb_failure; cb_arg->seq++; - return genlmsg_end(cb_arg->skb, data); + genlmsg_end(cb_arg->skb, data); + return 0; listall_cb_failure: genlmsg_cancel(cb_arg->skb, data); @@ -620,7 +621,8 @@ static int netlbl_mgmt_protocols_cb(struct sk_buff *skb, if (ret_val != 0) goto protocols_cb_failure; - return genlmsg_end(skb, data); + genlmsg_end(skb, data); + return 0; protocols_cb_failure: genlmsg_cancel(skb, data); diff --git a/net/netlabel/netlabel_unlabeled.c b/net/netlabel/netlabel_unlabeled.c index 78a63c18779e..aec7994f78cf 100644 --- a/net/netlabel/netlabel_unlabeled.c +++ b/net/netlabel/netlabel_unlabeled.c @@ -1163,7 +1163,8 @@ static int netlbl_unlabel_staticlist_gen(u32 cmd, goto list_cb_failure; cb_arg->seq++; - return genlmsg_end(cb_arg->skb, data); + genlmsg_end(cb_arg->skb, data); + return 0; list_cb_failure: genlmsg_cancel(cb_arg->skb, data); -- cgit v1.2.3-55-g7522