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From: Ingo Molnar <mingo@kernel.org>
To: Oleg Nesterov <oleg@redhat.com>
Cc: linux-kernel@vger.kernel.org,
	Andy Lutomirski <luto@amacapital.net>,
	Andrew Morton <akpm@linux-foundation.org>,
	Dave Hansen <dave@sr71.net>,
	Peter Zijlstra <peterz@infradead.org>,
	Borislav Petkov <bp@alien8.de>, "H . Peter Anvin" <hpa@zytor.com>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	Uros Bizjak <ubizjak@gmail.com>
Subject: Re: [PATCH 2/3] x86/fpu: Remove the thread::fpu pointer
Date: Sat, 8 Jun 2024 08:55:35 +0200	[thread overview]
Message-ID: <ZmQAZ-REghlJmax-@gmail.com> (raw)
In-Reply-To: <ZmF5IhYp5JiiMHgv@gmail.com>


* Ingo Molnar <mingo@kernel.org> wrote:

> 
> * Oleg Nesterov <oleg@redhat.com> wrote:
> 
> > On 06/05, Ingo Molnar wrote:
> > >
> > > @@ -591,13 +591,11 @@ int fpu_clone(struct task_struct *dst, unsigned long clone_flags, bool minimal,
> > >  	 * This is safe because task_struct size is a multiple of cacheline size.
> > >  	 */
> > >  	struct fpu *dst_fpu = (void *)dst + sizeof(*dst);
> > > -	struct fpu *src_fpu = current->thread.fpu;
> > > +	struct fpu *src_fpu = x86_task_fpu(current);
> > 
> > I think this patch can also change
> > 
> > 	struct fpu *dst_fpu = (void *)dst + sizeof(*dst);
> > 
> > above to use x86_task_fpu(dst).
> 
> Yeah, so I'd prefer to keep it open coded, because of the comment and the 
> debug check makes a lot more sense if the pointer calculation is visible:

On a second thought I changed it to your suggested variant:

        struct fpu *src_fpu = x86_task_fpu(current);
        struct fpu *dst_fpu = x86_task_fpu(dst);

because you are right, it's in fact easier to read this way.

Thanks,

	Ingo

  reply	other threads:[~2024-06-08  6:55 UTC|newest]

Thread overview: 30+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-06-05  8:35 [PATCH 0/3, v3] x86/fpu: Remove the thread::fpu pointer Ingo Molnar
2024-06-05  8:35 ` [PATCH 1/3] x86/fpu: Make task_struct::thread constant size Ingo Molnar
2024-06-05 19:04   ` Chang S. Bae
2024-06-06  9:30     ` [PATCH] x86/fpu: Fix stale comment in ex_handler_fprestore() Ingo Molnar
2024-06-06 15:55       ` Chang S. Bae
2024-06-05  8:35 ` [PATCH 2/3] x86/fpu: Remove the thread::fpu pointer Ingo Molnar
2024-06-05 13:38   ` Oleg Nesterov
2024-06-06  8:53     ` Ingo Molnar
2024-06-08  6:55       ` Ingo Molnar [this message]
2024-06-08  7:26         ` Ingo Molnar
2024-06-08 10:10           ` Oleg Nesterov
2024-06-25  5:26   ` Edgecombe, Rick P
2024-06-25 13:45     ` Edgecombe, Rick P
2024-06-05  8:35 ` [PATCH 3/3] x86/fpu: Remove init_task FPU state dependencies, add debugging warning Ingo Molnar
2024-06-05 14:17   ` Oleg Nesterov
2024-06-05 16:08     ` Linus Torvalds
2024-06-05 16:26       ` Oleg Nesterov
2024-06-05 17:28         ` Linus Torvalds
2024-06-06  8:30           ` [PATCH 3/3, v4] x86/fpu: Remove init_task FPU state dependencies, add debugging warning for PF_KTHREAD tasks Ingo Molnar
2024-06-06  8:46             ` [PATCH 4/3] x86/fpu: Push 'fpu' pointer calculation into the fpu__drop() call Ingo Molnar
2024-06-06  8:47             ` [PATCH 5/3] x86/fpu: Make sure x86_task_fpu() doesn't get called for PF_KTHREAD tasks during exit Ingo Molnar
2024-06-06  8:48             ` [PATCH 3/3, v4] x86/fpu: Remove init_task FPU state dependencies, add debugging warning for PF_KTHREAD tasks Ingo Molnar
2024-06-06 12:00             ` Oleg Nesterov
2024-06-07 10:56               ` Ingo Molnar
2024-06-24  6:47   ` [PATCH 3/3] x86/fpu: Remove init_task FPU state dependencies, add debugging warning Ning, Hongyu
2024-06-27  3:50     ` Ning, Hongyu
2024-06-05 21:21 ` [PATCH 0/3, v3] x86/fpu: Remove the thread::fpu pointer Brian Gerst
2024-06-06  9:06   ` [PATCH] x86/fpu: Introduce the x86_task_fpu() helper method Ingo Molnar
2024-06-06 15:35     ` Brian Gerst
2024-06-07 11:38       ` Ingo Molnar

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