linux-kernel - Re: x86/fpu: Don't export __kernel_fpu

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Message-ID: <20190109170935.e6b6rwzpk6dlruu4@linutronix.de>
Date:   Wed, 9 Jan 2019 18:09:35 +0100
From:   Sebastian Andrzej Siewior <bigeasy@...utronix.de>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     Marc Dionne <marc.c.dionne@...il.com>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        x86@...nel.org
Subject: Re: x86/fpu: Don't export __kernel_fpu_{begin,end}()

On 2019-01-09 17:52:35 [+0100], Greg Kroah-Hartman wrote:
> If there are no in-kernel users, the symbols should not be exported
> anymore.  That's nothing new, we have always done this.

The thing is that we had
  EXPORT_SYMBOL(__kernel_fpu_begin)
  EXPORT_SYMBOL_GPL(kernel_fpu_begin)

and now __kernel_fpu_begin() is no longer exported and static only.
All in kernel user (including the kvm module) use kernel_fpu_begin()
which is not available to proprietary modules. Hence Marc's mail.

> > On the other hand could we just drop EXPORT_SYMBOL_GPL? I doubt this
> > helps in any way yet please correct me if I am wrong. 
> 
> Yes, it helps, please leave it as-is.

As you say. I only notice that certain things used to work and then no
longer do because due to $rework it somehow become EXPORT_SYMBOL_GPL
only and people complain and we tend to switch the export back to
EXPORT_SYMBOL. I'm not aware of a case where it actually helped in
anyway.

> thanks,
> 
> greg k-h

Sebastian