linux-kernel - Re: math_state_restore and kernel_fpu

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Date:	Mon, 20 Jan 2014 19:22:51 -0700 (MST)
From:	Nate Eldredge <nate@...tsmathematics.com>
To:	George Spelvin <linux@...izon.com>
cc:	adilger@...ger.ca, arjan@...ux.intel.com, jack@...e.cz,
	linux-kernel@...r.kernel.org, maarten-baert@...mail.com,
	mingo@...e.hu, suresh.b.siddha@...el.com, tglx@...utronix.de,
	viro@...iv.linux.org.uk
Subject: Re: math_state_restore and kernel_fpu_end disable interrupts?

On Sun, 19 Jan 2014, George Spelvin wrote:

>> It's credited to Suresh Siddha, whom I've cc'ed (along with others who
>> signed off).  Suresh, if you're still around, could you comment on why
>> math_state_restore always leaves interrupts disabled, regardless of their
>> state on entry?  Is there a deep reason or is it a bug?
>
> What the comments seemed to be implying was that it was a bug to enter
> this code with interrupts enabled.  So the problem may be a little bit
> more systemic; expert counsel is required.

It would be kind of weird for code that requires disabled interrupts on 
entry to turn around and enable interrupts itself.  I agree that it would 
really help for a guru to take a look...

On which note, Suresh's email bounced :-(

-- 
Nate Eldredge
nate@...tsmathematics.com

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