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Message-ID: <20061102165524.GB3634@oleg>
Date: Thu, 2 Nov 2006 19:55:24 +0300
From: Oleg Nesterov <oleg@...sign.ru>
To: Andrew Morton <akpm@...l.org>
Cc: Thomas Graf <tgraf@...g.ch>, Shailabh Nagar <nagar@...son.ibm.com>,
Balbir Singh <balbir@...ibm.com>, Jay Lan <jlan@....com>,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH] taskstats: cleanup reply assembling
The same patch, but
- do not add 'BUG()' to the error path, Balbir and Shailabh
disagree.
- use '?:' in mk_reply as Balbir suggested.
[PATCH] taskstats: cleanup reply assembling
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.
Add a check for 'na == NULL' (this can't happen unless we mis-calculated
the size).
> genlmsg_cancel() is only required in error paths for dumping
> procedures.
Remove 'genlmsg_cancel()' calls and 'void *reply' (saves 227 bytes).
On 11/02, Balbir Singh wrote:
>
> > + aggr = TASKSTATS_TYPE_AGGR_TGID;
> > + if (type == TASKSTATS_TYPE_PID)
> > + aggr = TASKSTATS_TYPE_AGGR_PID;
>
> How about using
>
> aggr = (type == TASKSTATS_TYPE_PID) ? TASKSTATS_TYPE_AGGR_PID :
> TASKSTATS_TYPE_AGGR_TGID;
Change mk_reply() to use '?:'.
Signed-off-by: Oleg Nesterov <oleg@...sign.ru>
--- STATS/kernel/taskstats.c~1_nla_bug 2006-11-01 21:14:39.000000000 +0300
+++ STATS/kernel/taskstats.c 2006-11-02 19:39:27.000000000 +0300
@@ -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;
@@ -99,7 +99,6 @@ static int prepare_reply(struct genl_inf
}
*skbp = skb;
- *replyp = reply;
return 0;
}
@@ -356,11 +355,13 @@ static struct taskstats *mk_reply(struct
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));
@@ -378,7 +379,6 @@ static int taskstats_user_cmd(struct sk_
int rc = 0;
struct sk_buff *rep_skb;
struct taskstats *stats;
- void *reply;
size_t size;
cpumask_t mask;
@@ -400,7 +400,7 @@ static int taskstats_user_cmd(struct sk_
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;
@@ -409,27 +409,24 @@ static int taskstats_user_cmd(struct sk_
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;
@@ -466,7 +463,6 @@ void taskstats_exit(struct task_struct *
struct listener_list *listeners;
struct taskstats *stats;
struct sk_buff *rep_skb;
- void *reply;
size_t size;
int is_thread_group;
@@ -491,17 +487,17 @@ void taskstats_exit(struct task_struct *
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
@@ -511,16 +507,14 @@ void taskstats_exit(struct task_struct *
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);
}
-
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