linux-kernel - Re: [PATCH] x86, math-emu: fix init

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Date:	Wed, 4 Mar 2009 18:51:22 +0100
From:	Ingo Molnar <mingo@...e.hu>
To:	Daniel Glöckner <dg@...ix.com>
Cc:	"H. Peter Anvin" <hpa@...or.com>,
	Suresh Siddha <suresh.b.siddha@...el.com>,
	"Pallipadi, Venkatesh" <venkatesh.pallipadi@...el.com>,
	Arjan van de Ven <arjan@...radead.org>, x86@...nel.org,
	Bill Metzenthen <billm@...bpc.org.au>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] x86, math-emu: fix init_fpu for task != current


* Daniel Glöckner <dg@...ix.com> wrote:

> On 03/02/2009 08:52 PM, Ingo Molnar wrote:
> > * Daniel Glöckner <dg@...ix.com> wrote:
> [..]
> >> This patch creates a new function finit_task that takes a task_struct
> >> parameter. finit becomes a wrapper that simply calls finit_task with
> >> current. On the plus side this avoids many calls to get_current which
> >> would each resolve to an inline assembler mov instruction.
> [..]
> >> --- a/arch/x86/kernel/i387.c
> >> +++ b/arch/x86/kernel/i387.c
> >> @@ -136,7 +136,7 @@ int init_fpu(struct task_struct *tsk)
> >>  #ifdef CONFIG_X86_32
> >>  	if (!HAVE_HWFP) {
> >>  		memset(tsk->thread.xstate, 0, xstate_size);
> >> -		finit();
> >> +		finit_task(tsk);
> >>  		set_stopped_child_used_math(tsk);
> >>  		return 0;
> >>  	}
> [..]
> > 
> > ok, the fix looks good - but we sure want to define this 
> > function in the "# CONFIG_MATH_EMU is not set" case too, agreed?
> 
> To avoid linker errors if the compiler emits the call although 
> !HAVE_HWFP is always false? Sounds plausible. I also removed 
> finit from i387.h as the only other external call site, 
> reg_ld_str.c, gets its prototype from fpu_proto.h.

Could you please send a single combo patch with a full 
changelog, etc.

Thanks,

	Ingo
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