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From:   Arvind Sankar <nivedita@alum.mit.edu>
Date:   Sat, 25 Jan 2020 18:51:31 -0500
To:     "Luck, Tony" <tony.luck@intel.com>
Cc:     Arvind Sankar <nivedita@alum.mit.edu>,
        Thomas Gleixner <tglx@linutronix.de>,
        "Christopherson, Sean J" <sean.j.christopherson@intel.com>,
        Peter Zijlstra <peterz@infradead.org>,
        Ingo Molnar <mingo@kernel.org>,
        "Yu, Fenghua" <fenghua.yu@intel.com>,
        Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
        H Peter Anvin <hpa@zytor.com>,
        "Raj, Ashok" <ashok.raj@intel.com>,
        "Shankar, Ravi V" <ravi.v.shankar@intel.com>,
        linux-kernel <linux-kernel@vger.kernel.org>, x86 <x86@kernel.org>
Subject: Re: [PATCH v15] x86/split_lock: Enable split lock detection by kernel
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On Sat, Jan 25, 2020 at 01:50:03PM -0800, Luck, Tony wrote:
> > 
> > I might be missing something but shouldnt this be !nextflag given the
> > flag being unset is when the task wants sld?
> 
> That logic is convoluted ... but Thomas showed me a much better
> way that is also much simpler ... so this code has gone now. The
> new version is far easier to read (argument is flags for the new task
> that we are switching to)
> 
> void switch_to_sld(unsigned long tifn)
> {
>         __sld_msr_set(tifn & _TIF_SLD);
> }
> 
> -Tony

why doesnt this have the same problem though? tifn & _TIF_SLD still
needs to be logically negated no?