Le 03/10/2018 à 09:07, Nicholas Piggin a écrit :

On Wed, 3 Oct 2018 08:45:25 +0200
Christophe LEROY [off-list ref] wrote:

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Le 03/10/2018 à 08:30, Nicholas Piggin a écrit :

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On Wed, 3 Oct 2018 07:52:59 +0200
Christophe LEROY [off-list ref] wrote:
   

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Le 03/10/2018 à 07:34, Nicholas Piggin a écrit :

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On Mon,  1 Oct 2018 12:30:25 +0000 (UTC)
Christophe Leroy [off-list ref] wrote:
      

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thread_info is not anymore in the stack, so the entire stack
can now be used.

Nice.
      

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In the meantime, all pointers to the stacks are not anymore
pointers to thread_info so this patch changes them to void*

Wasn't this previously effectively already the case with patch
3/7? You had thread_info sized space left there, but it was not
used or initialized right? Does it make sense to move this part
of it to the previous patch?

Not really.

In 3/7 I changed the prototypes of two functions that really used the
pointer as a task pointer only.

I meant 2/7 here sorry.

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Here it change things that before 4/7 were really used as both stack
pointers and thread_info pointers.

And here I meant 3/7

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What uses it as a thread_info pointer? It seems more like a stack
with some amount of unused space in it but that's all.

Before 3/7, we have

void do_softirq_own_stack(void)
{
	struct thread_info *curtp, *irqtp;

	curtp = current_thread_info();
	irqtp = softirq_ctx[smp_processor_id()];
	irqtp->task = curtp->task;
	irqtp->flags = 0;
	call_do_softirq(irqtp);
	irqtp->task = NULL;

	/* Set any flag that may have been set on the
	 * alternate stack
	 */
	if (irqtp->flags)
		set_bits(irqtp->flags, &curtp->flags);
}

After 3/7, we have

   void do_softirq_own_stack(void)
   {
	struct thread_info *irqtp;

   	irqtp = softirq_ctx[smp_processor_id()];
   	call_do_softirq(irqtp);
   }


So now only we can change irqtp to void* can't we ?

In patch 3 we can, right? That's what I mean by moving from
thread_info * to void * in patch 3 rather than 4.

Ah ok, that's what you meant. Sorry.

But if you prefer not to, it's fine. Maybe it keeps patch 3
a little smaller.

Yes indeed, that's the idea, keep patch 3 to the strict minimum and do 
cleanups afterwards.

Christophe

Thanks,
Nick