linux-kernel - Re: [RFC v6][PATCH 3/9] x86 support for checkpoint/restart

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Date:	Fri, 10 Oct 2008 06:24:31 -0400
From:	Oren Laadan <orenl@...columbia.edu>
To:	Cedric Le Goater <clg@...ibm.com>
CC:	jeremy@...p.org, arnd@...db.de,
	containers@...ts.linux-foundation.org,
	linux-kernel@...r.kernel.org,
	Dave Hansen <dave@...ux.vnet.ibm.com>, linux-mm@...ck.org,
	Alexander Viro <viro@...iv.linux.org.uk>,
	"H. Peter Anvin" <hpa@...or.com>, Ingo Molnar <mingo@...e.hu>
Subject: Re: [RFC v6][PATCH 3/9] x86 support for checkpoint/restart



Cedric Le Goater wrote:
>> +int cr_read_cpu_fpu(struct cr_hdr_cpu *hh, struct task_struct *t)
>> +{
>> +	struct thread_struct *thread = &t->thread;
>> +
>> +	/* i387 + MMU + SSE */
>> +
>> +	preempt_disable();
>> +
>> +	__clear_fpu(t);		/* in case we used FPU in user mode */
>> +
>> +	if (!hh->used_math)
>> +		clear_used_math();
>> +	else {
>> +		if (hh->has_fxsr != cpu_has_fxsr) {
>> +			force_sig(SIGFPE, t);
>> +			return -EINVAL;
>> +		}
> 
> don't you need an init_fpu() around here ? because the task you restart might 
> not have used FPU yet.
> 
>> +		memcpy(&thread->xstate, &hh->xstate, sizeof(thread->xstate));
> 
> also i'd used 'xstate_size' instead of sizeof(thread->xstate)
> 

Yes, that was broken, and already fixed in for next round.

Thanks,

Oren.

> 
> thanks,
> 
> C.
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