mirror of
https://mirrors.bfsu.edu.cn/git/linux.git
synced 2024-11-16 08:44:21 +08:00
053c095a82
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>
137 lines
2.8 KiB
C
137 lines
2.8 KiB
C
/*
|
|
* Copyright (C) 2007 Red Hat, Inc. All rights reserved.
|
|
*
|
|
* This copyrighted material is made available to anyone wishing to use,
|
|
* modify, copy, or redistribute it subject to the terms and conditions
|
|
* of the GNU General Public License v.2.
|
|
*/
|
|
|
|
#include <net/genetlink.h>
|
|
#include <linux/dlm.h>
|
|
#include <linux/dlm_netlink.h>
|
|
#include <linux/gfp.h>
|
|
|
|
#include "dlm_internal.h"
|
|
|
|
static uint32_t dlm_nl_seqnum;
|
|
static uint32_t listener_nlportid;
|
|
|
|
static struct genl_family family = {
|
|
.id = GENL_ID_GENERATE,
|
|
.name = DLM_GENL_NAME,
|
|
.version = DLM_GENL_VERSION,
|
|
};
|
|
|
|
static int prepare_data(u8 cmd, struct sk_buff **skbp, size_t size)
|
|
{
|
|
struct sk_buff *skb;
|
|
void *data;
|
|
|
|
skb = genlmsg_new(size, GFP_NOFS);
|
|
if (!skb)
|
|
return -ENOMEM;
|
|
|
|
/* add the message headers */
|
|
data = genlmsg_put(skb, 0, dlm_nl_seqnum++, &family, 0, cmd);
|
|
if (!data) {
|
|
nlmsg_free(skb);
|
|
return -EINVAL;
|
|
}
|
|
|
|
*skbp = skb;
|
|
return 0;
|
|
}
|
|
|
|
static struct dlm_lock_data *mk_data(struct sk_buff *skb)
|
|
{
|
|
struct nlattr *ret;
|
|
|
|
ret = nla_reserve(skb, DLM_TYPE_LOCK, sizeof(struct dlm_lock_data));
|
|
if (!ret)
|
|
return NULL;
|
|
return nla_data(ret);
|
|
}
|
|
|
|
static int send_data(struct sk_buff *skb)
|
|
{
|
|
struct genlmsghdr *genlhdr = nlmsg_data((struct nlmsghdr *)skb->data);
|
|
void *data = genlmsg_data(genlhdr);
|
|
|
|
genlmsg_end(skb, data);
|
|
|
|
return genlmsg_unicast(&init_net, skb, listener_nlportid);
|
|
}
|
|
|
|
static int user_cmd(struct sk_buff *skb, struct genl_info *info)
|
|
{
|
|
listener_nlportid = info->snd_portid;
|
|
printk("user_cmd nlpid %u\n", listener_nlportid);
|
|
return 0;
|
|
}
|
|
|
|
static struct genl_ops dlm_nl_ops[] = {
|
|
{
|
|
.cmd = DLM_CMD_HELLO,
|
|
.doit = user_cmd,
|
|
},
|
|
};
|
|
|
|
int __init dlm_netlink_init(void)
|
|
{
|
|
return genl_register_family_with_ops(&family, dlm_nl_ops);
|
|
}
|
|
|
|
void dlm_netlink_exit(void)
|
|
{
|
|
genl_unregister_family(&family);
|
|
}
|
|
|
|
static void fill_data(struct dlm_lock_data *data, struct dlm_lkb *lkb)
|
|
{
|
|
struct dlm_rsb *r = lkb->lkb_resource;
|
|
|
|
memset(data, 0, sizeof(struct dlm_lock_data));
|
|
|
|
data->version = DLM_LOCK_DATA_VERSION;
|
|
data->nodeid = lkb->lkb_nodeid;
|
|
data->ownpid = lkb->lkb_ownpid;
|
|
data->id = lkb->lkb_id;
|
|
data->remid = lkb->lkb_remid;
|
|
data->status = lkb->lkb_status;
|
|
data->grmode = lkb->lkb_grmode;
|
|
data->rqmode = lkb->lkb_rqmode;
|
|
if (lkb->lkb_ua)
|
|
data->xid = lkb->lkb_ua->xid;
|
|
if (r) {
|
|
data->lockspace_id = r->res_ls->ls_global_id;
|
|
data->resource_namelen = r->res_length;
|
|
memcpy(data->resource_name, r->res_name, r->res_length);
|
|
}
|
|
}
|
|
|
|
void dlm_timeout_warn(struct dlm_lkb *lkb)
|
|
{
|
|
struct sk_buff *uninitialized_var(send_skb);
|
|
struct dlm_lock_data *data;
|
|
size_t size;
|
|
int rv;
|
|
|
|
size = nla_total_size(sizeof(struct dlm_lock_data)) +
|
|
nla_total_size(0); /* why this? */
|
|
|
|
rv = prepare_data(DLM_CMD_TIMEOUT, &send_skb, size);
|
|
if (rv < 0)
|
|
return;
|
|
|
|
data = mk_data(send_skb);
|
|
if (!data) {
|
|
nlmsg_free(send_skb);
|
|
return;
|
|
}
|
|
|
|
fill_data(data, lkb);
|
|
|
|
send_data(send_skb);
|
|
}
|
|
|