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SubjectRe: [RFC][PATCH 03/10] taskstats: Split fill_pid function
* Michael Holzheu <holzheu@linux.vnet.ibm.com> [2010-09-23 16:01:07]:

> Subject: [PATCH] taskstats: Split fill_pid function
>
> From: Michael Holzheu <holzheu@linux.vnet.ibm.com>
>
> Separate the finding of a task_struct by pid or tgid from filling the taskstats
> data. This makes the code more readable.
>
> Signed-off-by: Michael Holzheu <holzheu@linux.vnet.ibm.com>
> ---
> kernel/taskstats.c | 50 +++++++++++++++++++++-----------------------------
> 1 file changed, 21 insertions(+), 29 deletions(-)
>
> --- a/kernel/taskstats.c
> +++ b/kernel/taskstats.c
> @@ -175,22 +175,8 @@ static void send_cpu_listeners(struct sk
> up_write(&listeners->sem);
> }
>
> -static int fill_pid(pid_t pid, struct task_struct *tsk,
> - struct taskstats *stats)
> +static void fill_stats(struct task_struct *tsk, struct taskstats *stats)
> {
> - int rc = 0;
> -
> - if (!tsk) {
> - rcu_read_lock();
> - tsk = find_task_by_vpid(pid);
> - if (tsk)
> - get_task_struct(tsk);
> - rcu_read_unlock();
> - if (!tsk)
> - return -ESRCH;
> - } else
> - get_task_struct(tsk);
> -
> memset(stats, 0, sizeof(*stats));
> /*
> * Each accounting subsystem adds calls to its functions to
> @@ -209,17 +195,27 @@ static int fill_pid(pid_t pid, struct ta
>
> /* fill in extended acct fields */
> xacct_add_tsk(stats, tsk);
> +}
>
> - /* Define err: label here if needed */
> - put_task_struct(tsk);
> - return rc;
> +static int fill_stats_for_pid(pid_t pid, struct taskstats *stats)
> +{
> + struct task_struct *tsk;
>
> + rcu_read_lock();
> + tsk = find_task_by_vpid(pid);
> + if (tsk)
> + get_task_struct(tsk);
> + rcu_read_unlock();
> + if (!tsk)
> + return -ESRCH;
> + fill_stats(tsk, stats);
> + put_task_struct(tsk);
> + return 0;
> }
>
> -static int fill_tgid(pid_t tgid, struct task_struct *first,
> - struct taskstats *stats)
> +static int fill_stats_for_tgid(pid_t tgid, struct taskstats *stats)
> {
> - struct task_struct *tsk;
> + struct task_struct *tsk, *first;
> unsigned long flags;
> int rc = -ESRCH;
>
> @@ -228,8 +224,7 @@ static int fill_tgid(pid_t tgid, struct
> * leaders who are already counted with the dead tasks
> */
> rcu_read_lock();
> - if (!first)
> - first = find_task_by_vpid(tgid);
> + first = find_task_by_vpid(tgid);
>
> if (!first || !lock_task_sighand(first, &flags))
> goto out;
> @@ -268,7 +263,6 @@ out:
> return rc;
> }
>
> -
> static void fill_tgid_exit(struct task_struct *tsk)
> {
> unsigned long flags;
> @@ -477,7 +471,7 @@ static int cmd_attr_pid(struct genl_info
> if (!stats)
> goto err;
>
> - rc = fill_pid(pid, NULL, stats);
> + rc = fill_stats_for_pid(pid, stats);
> if (rc < 0)
> goto err;
> return send_reply(rep_skb, info);
> @@ -507,7 +501,7 @@ static int cmd_attr_tgid(struct genl_inf
> if (!stats)
> goto err;
>
> - rc = fill_tgid(tgid, NULL, stats);
> + rc = fill_stats_for_tgid(tgid, stats);
> if (rc < 0)
> goto err;
> return send_reply(rep_skb, info);
> @@ -593,9 +587,7 @@ void taskstats_exit(struct task_struct *
> if (!stats)
> goto err;
>
> - rc = fill_pid(-1, tsk, stats);
> - if (rc < 0)
> - goto err;
> + fill_stats(tsk, stats);
>
> /*
> * Doesn't matter if tsk is the leader or the last group member leaving
>
>


Acked-by: Balbir Singh <balbir@linux.vnet.ibm.com>


--
Three Cheers,
Balbir


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