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[PATCH] taskstats: cleanup reply assembling

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Thomas Graf wrote:
>
> nla_nest_start() may return NULL, either rely on prepare_reply() to be
> correct and BUG() on failure or do proper error handling for all
> functions.

nla_put() in taskstat.c can fail only if the 'size' argument of alloc_skb()
was not right. This is a kernel bug, we should not hide it. So add 'BUG()'
on error path and check for 'na == NULL'.

> genlmsg_cancel() is only required in error paths for dumping
> procedures.

So we can remove 'genlmsg_cancel()' calls and 'void *reply' (saves 227 bytes).

Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Cc: Thomas Graf <tgraf@suug.ch>
Cc: Shailabh Nagar <nagar@watson.ibm.com>
Cc: Balbir Singh <balbir@in.ibm.com>
Cc: Jay Lan <jlan@sgi.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This commit is contained in:
Oleg Nesterov 2006-12-06 20:36:55 -08:00 committed by Linus Torvalds
parent 51de4d9085
commit 3716748530
1 changed files with 16 additions and 22 deletions
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38
kernel/taskstats.c
View file

@ -69,7 +69,7 @@ enum actions {
};
static int prepare_reply(struct genl_info *info, u8 cmd, struct sk_buff **skbp,
void **replyp, size_t size)
size_t size)
{
struct sk_buff *skb;
void *reply;
@ -94,7 +94,6 @@ static int prepare_reply(struct genl_info *info, u8 cmd, struct sk_buff **skbp,
}
*skbp = skb;
*replyp = reply;
return 0;
}
@ -351,11 +350,13 @@ static struct taskstats *mk_reply(struct sk_buff *skb, int type, u32 pid)
struct nlattr *na, *ret;
int aggr;
aggr = TASKSTATS_TYPE_AGGR_TGID;
if (type == TASKSTATS_TYPE_PID)
aggr = TASKSTATS_TYPE_AGGR_PID;
aggr = (type == TASKSTATS_TYPE_PID)
? TASKSTATS_TYPE_AGGR_PID
: TASKSTATS_TYPE_AGGR_TGID;
na = nla_nest_start(skb, aggr);
if (!na)
goto err;
if (nla_put(skb, type, sizeof(pid), &pid) < 0)
goto err;
ret = nla_reserve(skb, TASKSTATS_TYPE_STATS, sizeof(struct taskstats));
@ -373,7 +374,6 @@ static int taskstats_user_cmd(struct sk_buff *skb, struct genl_info *info)
int rc = 0;
struct sk_buff *rep_skb;
struct taskstats *stats;
void *reply;
size_t size;
cpumask_t mask;
@ -395,7 +395,7 @@ static int taskstats_user_cmd(struct sk_buff *skb, struct genl_info *info)
size = nla_total_size(sizeof(u32)) +
nla_total_size(sizeof(struct taskstats)) + nla_total_size(0);
rc = prepare_reply(info, TASKSTATS_CMD_NEW, &rep_skb, &reply, size);
rc = prepare_reply(info, TASKSTATS_CMD_NEW, &rep_skb, size);
if (rc < 0)
return rc;
@ -404,27 +404,24 @@ static int taskstats_user_cmd(struct sk_buff *skb, struct genl_info *info)
u32 pid = nla_get_u32(info->attrs[TASKSTATS_CMD_ATTR_PID]);
stats = mk_reply(rep_skb, TASKSTATS_TYPE_PID, pid);
if (!stats)
goto nla_err;
goto err;
rc = fill_pid(pid, NULL, stats);
if (rc < 0)
goto nla_err;
goto err;
} else if (info->attrs[TASKSTATS_CMD_ATTR_TGID]) {
u32 tgid = nla_get_u32(info->attrs[TASKSTATS_CMD_ATTR_TGID]);
stats = mk_reply(rep_skb, TASKSTATS_TYPE_TGID, tgid);
if (!stats)
goto nla_err;
goto err;
rc = fill_tgid(tgid, NULL, stats);
if (rc < 0)
goto nla_err;
goto err;
} else
goto err;
return send_reply(rep_skb, info->snd_pid);
nla_err:
genlmsg_cancel(rep_skb, reply);
err:
nlmsg_free(rep_skb);
return rc;
@ -461,7 +458,6 @@ void taskstats_exit(struct task_struct *tsk, int group_dead)
struct listener_list *listeners;
struct taskstats *stats;
struct sk_buff *rep_skb;
void *reply;
size_t size;
int is_thread_group;
@ -486,17 +482,17 @@ void taskstats_exit(struct task_struct *tsk, int group_dead)
if (list_empty(&listeners->list))
return;
rc = prepare_reply(NULL, TASKSTATS_CMD_NEW, &rep_skb, &reply, size);
rc = prepare_reply(NULL, TASKSTATS_CMD_NEW, &rep_skb, size);
if (rc < 0)
return;
stats = mk_reply(rep_skb, TASKSTATS_TYPE_PID, tsk->pid);
if (!stats)
goto nla_err;
goto err;
rc = fill_pid(tsk->pid, tsk, stats);
if (rc < 0)
goto nla_err;
goto err;
/*
* Doesn't matter if tsk is the leader or the last group member leaving
@ -506,16 +502,14 @@ void taskstats_exit(struct task_struct *tsk, int group_dead)
stats = mk_reply(rep_skb, TASKSTATS_TYPE_TGID, tsk->tgid);
if (!stats)
goto nla_err;
goto err;
memcpy(stats, tsk->signal->stats, sizeof(*stats));
send:
send_cpu_listeners(rep_skb, listeners);
return;
nla_err:
genlmsg_cancel(rep_skb, reply);
err:
nlmsg_free(rep_skb);
}