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linux-next/net/ieee802154/netlink.c
Johannes Berg 053c095a82 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>
2015-01-18 01:03:45 -05:00

153 lines
4.5 KiB
C

/*
* Netlink interface for IEEE 802.15.4 stack
*
* Copyright 2007, 2008 Siemens AG
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2
* as published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* Written by:
* Sergey Lapin <slapin@ossfans.org>
* Dmitry Eremin-Solenikov <dbaryshkov@gmail.com>
* Maxim Osipov <maxim.osipov@siemens.com>
*/
#include <linux/kernel.h>
#include <linux/gfp.h>
#include <net/genetlink.h>
#include <linux/nl802154.h>
#include "ieee802154.h"
static unsigned int ieee802154_seq_num;
static DEFINE_SPINLOCK(ieee802154_seq_lock);
struct genl_family nl802154_family = {
.id = GENL_ID_GENERATE,
.hdrsize = 0,
.name = IEEE802154_NL_NAME,
.version = 1,
.maxattr = IEEE802154_ATTR_MAX,
};
/* Requests to userspace */
struct sk_buff *ieee802154_nl_create(int flags, u8 req)
{
void *hdr;
struct sk_buff *msg = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_ATOMIC);
unsigned long f;
if (!msg)
return NULL;
spin_lock_irqsave(&ieee802154_seq_lock, f);
hdr = genlmsg_put(msg, 0, ieee802154_seq_num++,
&nl802154_family, flags, req);
spin_unlock_irqrestore(&ieee802154_seq_lock, f);
if (!hdr) {
nlmsg_free(msg);
return NULL;
}
return msg;
}
int ieee802154_nl_mcast(struct sk_buff *msg, unsigned int group)
{
struct nlmsghdr *nlh = nlmsg_hdr(msg);
void *hdr = genlmsg_data(nlmsg_data(nlh));
genlmsg_end(msg, hdr);
return genlmsg_multicast(&nl802154_family, msg, 0, group, GFP_ATOMIC);
}
struct sk_buff *ieee802154_nl_new_reply(struct genl_info *info,
int flags, u8 req)
{
void *hdr;
struct sk_buff *msg = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_ATOMIC);
if (!msg)
return NULL;
hdr = genlmsg_put_reply(msg, info,
&nl802154_family, flags, req);
if (!hdr) {
nlmsg_free(msg);
return NULL;
}
return msg;
}
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));
genlmsg_end(msg, hdr);
return genlmsg_reply(msg, info);
}
static const struct genl_ops ieee8021154_ops[] = {
/* see nl-phy.c */
IEEE802154_DUMP(IEEE802154_LIST_PHY, ieee802154_list_phy,
ieee802154_dump_phy),
IEEE802154_OP(IEEE802154_ADD_IFACE, ieee802154_add_iface),
IEEE802154_OP(IEEE802154_DEL_IFACE, ieee802154_del_iface),
/* see nl-mac.c */
IEEE802154_OP(IEEE802154_ASSOCIATE_REQ, ieee802154_associate_req),
IEEE802154_OP(IEEE802154_ASSOCIATE_RESP, ieee802154_associate_resp),
IEEE802154_OP(IEEE802154_DISASSOCIATE_REQ, ieee802154_disassociate_req),
IEEE802154_OP(IEEE802154_SCAN_REQ, ieee802154_scan_req),
IEEE802154_OP(IEEE802154_START_REQ, ieee802154_start_req),
IEEE802154_DUMP(IEEE802154_LIST_IFACE, ieee802154_list_iface,
ieee802154_dump_iface),
IEEE802154_OP(IEEE802154_SET_MACPARAMS, ieee802154_set_macparams),
IEEE802154_OP(IEEE802154_LLSEC_GETPARAMS, ieee802154_llsec_getparams),
IEEE802154_OP(IEEE802154_LLSEC_SETPARAMS, ieee802154_llsec_setparams),
IEEE802154_DUMP(IEEE802154_LLSEC_LIST_KEY, NULL,
ieee802154_llsec_dump_keys),
IEEE802154_OP(IEEE802154_LLSEC_ADD_KEY, ieee802154_llsec_add_key),
IEEE802154_OP(IEEE802154_LLSEC_DEL_KEY, ieee802154_llsec_del_key),
IEEE802154_DUMP(IEEE802154_LLSEC_LIST_DEV, NULL,
ieee802154_llsec_dump_devs),
IEEE802154_OP(IEEE802154_LLSEC_ADD_DEV, ieee802154_llsec_add_dev),
IEEE802154_OP(IEEE802154_LLSEC_DEL_DEV, ieee802154_llsec_del_dev),
IEEE802154_DUMP(IEEE802154_LLSEC_LIST_DEVKEY, NULL,
ieee802154_llsec_dump_devkeys),
IEEE802154_OP(IEEE802154_LLSEC_ADD_DEVKEY, ieee802154_llsec_add_devkey),
IEEE802154_OP(IEEE802154_LLSEC_DEL_DEVKEY, ieee802154_llsec_del_devkey),
IEEE802154_DUMP(IEEE802154_LLSEC_LIST_SECLEVEL, NULL,
ieee802154_llsec_dump_seclevels),
IEEE802154_OP(IEEE802154_LLSEC_ADD_SECLEVEL,
ieee802154_llsec_add_seclevel),
IEEE802154_OP(IEEE802154_LLSEC_DEL_SECLEVEL,
ieee802154_llsec_del_seclevel),
};
static const struct genl_multicast_group ieee802154_mcgrps[] = {
[IEEE802154_COORD_MCGRP] = { .name = IEEE802154_MCAST_COORD_NAME, },
[IEEE802154_BEACON_MCGRP] = { .name = IEEE802154_MCAST_BEACON_NAME, },
};
int __init ieee802154_nl_init(void)
{
return genl_register_family_with_ops_groups(&nl802154_family,
ieee8021154_ops,
ieee802154_mcgrps);
}
void ieee802154_nl_exit(void)
{
genl_unregister_family(&nl802154_family);
}