[PATCH] don't use task->pid/tgid in same_thread_group/has_group_leader_pid

[PATCH] don't use task->pid/tgid in same_thread_group/has_group_leader_pid

[Oleg Nesterov]

task_struct->pid/tgid should go away.

1. Change same_thread_group() to use task->signal for comparison.

2. Change has_group_leader_pid(task) to compare task_pid(task) with
   signal->leader_pid.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
---
 include/linux/sched.h |    8 ++++----
 1 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/include/linux/sched.h b/include/linux/sched.h
index 178a8d9..ce51dfd 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -2179,15 +2179,15 @@ static inline bool thread_group_leader(struct task_struct *p)
  * all we care about is that we have a task with the appropriate
  * pid, we don't actually care if we have the right task.
  */
-static inline int has_group_leader_pid(struct task_struct *p)
+static inline bool has_group_leader_pid(struct task_struct *p)
 {
-	return p->pid == p->tgid;
+	return task_pid(p) == p->signal->leader_pid;
 }
 
 static inline
-int same_thread_group(struct task_struct *p1, struct task_struct *p2)
+bool same_thread_group(struct task_struct *p1, struct task_struct *p2)
 {
-	return p1->tgid == p2->tgid;
+	return p1->signal == p2->signal;
 }
 
 static inline struct task_struct *next_thread(const struct task_struct *p)
-- 
1.5.5.1

Re: [PATCH] don't use task->pid/tgid in same_thread_group/has_group_leader_pid

[Eric W. Biederman]

Oleg Nesterov <oleg@redhat.com> writes:

> task_struct->pid/tgid should go away.
>
> 1. Change same_thread_group() to use task->signal for comparison.
>
> 2. Change has_group_leader_pid(task) to compare task_pid(task) with
>    signal->leader_pid.

Reviewed-by: "Eric W. Biederman" <ebiederm@xmission.com>

This change looks good, thanks.

The posix cpu timers usage of has_group_leader_pid looks a little iffy,
but this change doesn't look like it will break them.

Thanks for this cleanup Oleg.

> Signed-off-by: Oleg Nesterov <oleg@redhat.com>
> ---
>  include/linux/sched.h |    8 ++++----
>  1 files changed, 4 insertions(+), 4 deletions(-)
>
> diff --git a/include/linux/sched.h b/include/linux/sched.h
> index 178a8d9..ce51dfd 100644
> --- a/include/linux/sched.h
> +++ b/include/linux/sched.h
> @@ -2179,15 +2179,15 @@ static inline bool thread_group_leader(struct task_struct *p)
>   * all we care about is that we have a task with the appropriate
>   * pid, we don't actually care if we have the right task.
>   */
> -static inline int has_group_leader_pid(struct task_struct *p)
> +static inline bool has_group_leader_pid(struct task_struct *p)
>  {
> -	return p->pid == p->tgid;
> +	return task_pid(p) == p->signal->leader_pid;
>  }
>  
>  static inline
> -int same_thread_group(struct task_struct *p1, struct task_struct *p2)
> +bool same_thread_group(struct task_struct *p1, struct task_struct *p2)
>  {
> -	return p1->tgid == p2->tgid;
> +	return p1->signal == p2->signal;
>  }
>  
>  static inline struct task_struct *next_thread(const struct task_struct *p)