Re: [PATCH v3 1/1] kthread: allocate kthread structure using kmalloc

From	Thomas Gleixner <tglx@linutronix.de>
Newsgroups	linux.kernel
Subject	Re: [PATCH v3 1/1] kthread: allocate kthread structure using kmalloc
Date	2016-10-26 20:40 +0200
Message-ID	<swBhf-7Ar-5@gated-at.bofh.it> (permalink)
References	(2 earlier) <swc9c-7vM-29@gated-at.bofh.it> <swdeW-8ec-11@gated-at.bofh.it> <swxdE-4QU-23@gated-at.bofh.it> <swy01-5vO-15@gated-at.bofh.it> <swyMp-5PJ-29@gated-at.bofh.it>
Organization	linux.* mail to news gateway

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On Wed, 26 Oct 2016, Oleg Nesterov wrote:
> On 10/26, Thomas Gleixner wrote:
> >
> > On Wed, 26 Oct 2016, Oleg Nesterov wrote:
> > > +static inline void set_kthread_struct(void *kthread)
> > > +{
> > > +	/*
> > > +	 * We abuse ->set_child_tid to avoid the new member and because it
> > > +	 * can't be wrongly copied by copy_process(). We also rely on fact
> > > +	 * that the caller can't exec, so PF_KTHREAD can't be cleared.
> > > +	 */
> > > +	current->set_child_tid = (__force void __user *)kthread;
> >
> > Can we pretty please avoid this type casting? We only have 5 places using
> > set_child_tid. So we can really make it a proper union
> 
> Yes, I thought about anonymous union too, the only problem is that
> it will need more comments ;)

Be careful with anonymous unions. There are a few pitfalls with older
compilers. That's why I said make it a proper union and fixup the 5 usage
sites. It might work in this case, but you've been warned :)

Thanks,

	tglx

Thread

[PATCH v3 1/1] kthread: allocate kthread structure using kmalloc Roman Pen <roman.penyaev@profitbricks.com> - 2016-10-25 13:10 +0200
  Re: [PATCH v3 1/1] kthread: allocate kthread structure using         kmalloc Oleg Nesterov <oleg@redhat.com> - 2016-10-25 16:10 +0200
    Re: [PATCH v3 1/1] kthread: allocate kthread structure using kmalloc Roman Penyaev <roman.penyaev@profitbricks.com> - 2016-10-25 17:50 +0200
    Re: [PATCH v3 1/1] kthread: allocate kthread structure using         kmalloc Oleg Nesterov <oleg@redhat.com> - 2016-10-25 17:50 +0200
      Re: [PATCH v3 1/1] kthread: allocate kthread structure using         kmalloc Oleg Nesterov <oleg@redhat.com> - 2016-10-25 18:20 +0200
      Re: [PATCH v3 1/1] kthread: allocate kthread structure using kmalloc Roman Penyaev <roman.penyaev@profitbricks.com> - 2016-10-25 18:20 +0200
      Re: [PATCH v3 1/1] kthread: allocate kthread structure using kmalloc Andy Lutomirski <luto@amacapital.net> - 2016-10-25 19:00 +0200
        Re: [PATCH v3 1/1] kthread: allocate kthread structure using kmalloc Oleg Nesterov <oleg@redhat.com> - 2016-10-26 16:20 +0200
          Re: [PATCH v3 1/1] kthread: allocate kthread structure using  kmalloc Thomas Gleixner <tglx@linutronix.de> - 2016-10-26 17:10 +0200
            Re: [PATCH v3 1/1] kthread: allocate kthread structure using         kmalloc Oleg Nesterov <oleg@redhat.com> - 2016-10-26 18:00 +0200
              Re: [PATCH v3 1/1] kthread: allocate kthread structure using  kmalloc Thomas Gleixner <tglx@linutronix.de> - 2016-10-26 20:40 +0200
                [PATCH 2/2] Revert "kthread: Pin the stack via  try_get_task_stack()/put_task_stack() in to_live_kthread() function" Oleg Nesterov <oleg@redhat.com> - 2016-10-28 18:20 +0200
                Re: [PATCH 2/2] Revert "kthread: Pin the stack via  try_get_task_stack()/put_task_stack() in to_live_kthread() function" Thomas Gleixner <tglx@linutronix.de> - 2016-10-28 21:00 +0200
                [PATCH 0/2] kthread: make struct kthread kmalloc'ed Oleg Nesterov <oleg@redhat.com> - 2016-10-28 18:20 +0200
                [PATCH 1/2] kthread: make struct kthread kmalloc'ed Oleg Nesterov <oleg@redhat.com> - 2016-10-28 18:20 +0200
                Re: [PATCH 1/2] kthread: make struct kthread kmalloc'ed Thomas Gleixner <tglx@linutronix.de> - 2016-10-28 21:00 +0200
                Re: [PATCH 0/2] kthread: make struct kthread kmalloc'ed Thomas Gleixner <tglx@linutronix.de> - 2016-10-28 20:50 +0200
                [PATCH 0/2] kthread: kill to_live_kthread() Oleg Nesterov <oleg@redhat.com> - 2016-10-31 21:10 +0100
                [PATCH 1/2] kthread: don't use to_live_kthread() in kthread_stop() Oleg Nesterov <oleg@redhat.com> - 2016-10-31 21:10 +0100
                Re: [PATCH 1/2] kthread: don't use to_live_kthread() in  kthread_stop() Thomas Gleixner <tglx@linutronix.de> - 2016-11-09 09:10 +0100
                [PATCH 2/2] kthread: don't use to_live_kthread() in kthread_park()  and kthread_unpark() Oleg Nesterov <oleg@redhat.com> - 2016-10-31 21:10 +0100
                Re: [PATCH 2/2] kthread: don't use to_live_kthread() in kthread_park()  and kthread_unpark() Thomas Gleixner <tglx@linutronix.de> - 2016-11-09 09:50 +0100
                Re: [PATCH 2/2] kthread: don't use to_live_kthread() in         kthread_park() and kthread_unpark() Oleg Nesterov <oleg@redhat.com> - 2016-11-09 18:30 +0100
                [PATCH 1/1] kthread: don't abuse kthread_create_on_cpu() in  __kthread_create_worker() Oleg Nesterov <oleg@redhat.com> - 2016-11-10 18:30 +0100
                [PATCH 0/1] kthread: don't abuse kthread_create_on_cpu() in  __kthread_create_worker() Oleg Nesterov <oleg@redhat.com> - 2016-11-10 18:30 +0100
                Re: [PATCH 0/2] kthread: kill to_live_kthread() Andy Lutomirski <luto@amacapital.net> - 2016-11-07 19:40 +0100
          Re: [PATCH v3 1/1] kthread: allocate kthread structure using         kmalloc Oleg Nesterov <oleg@redhat.com> - 2016-10-26 18:20 +0200
          Re: [PATCH v3 1/1] kthread: allocate kthread structure using kmalloc Josh Poimboeuf <jpoimboe@redhat.com> - 2016-10-27 05:00 +0200
            Re: [PATCH v3 1/1] kthread: allocate kthread structure using         kmalloc Oleg Nesterov <oleg@redhat.com> - 2016-10-27 16:00 +0200

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