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SubjectRe: [PATCH] pids: introduce find_get_task_by_vpid helper
On Thu, Oct 26, 2017 at 03:58:25PM +0200, Oleg Nesterov wrote:
> On 10/26, Mike Rapoport wrote:
> >
> > There are several functions that do find_task_by_vpid() followed by
> > get_task_struct(). We can use a helper function instead.
>
> Yes, agreed, I was going to do this many times.
>
> > --- a/kernel/futex.c
> > +++ b/kernel/futex.c
> > @@ -870,12 +870,7 @@ static struct task_struct *futex_find_get_task(pid_t pid)
> > {
> > struct task_struct *p;
> >
> > - rcu_read_lock();
> > - p = find_task_by_vpid(pid);
> > - if (p)
> > - get_task_struct(p);
> > -
> > - rcu_read_unlock();
> > + p = find_get_task_by_vpid(pid);
> >
> > return p;
>
> OK, but then I think you should remove futex_find_get_task() and convert
> it callers to use the new helper.

Agree. My cocci script was too simple :)

> > @@ -1103,11 +1103,7 @@ static struct task_struct *ptrace_get_task_struct(pid_t pid)
> > {
> > struct task_struct *child;
> >
> > - rcu_read_lock();
> > - child = find_task_by_vpid(pid);
> > - if (child)
> > - get_task_struct(child);
> > - rcu_read_unlock();
> > + child = find_get_task_by_vpid(pid);
> >
> > if (!child)
> > return ERR_PTR(-ESRCH);
>
> The same. ptrace_get_task_struct() should die imo.

Yeah, we could just return -ESRCH in ptrace_get_task_struct users instead
of all the ERR_PTR and PTR_ERR conversions...

> Oleg.
>

--
Sincerely yours,
Mike.

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