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Date:   Fri, 16 Oct 2020 22:42:16 -0700
From:   Ira Weiny <ira.weiny@intel.com>
To:     Peter Zijlstra <peterz@infradead.org>
Cc:     Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
        Andy Lutomirski <luto@kernel.org>,
        Fenghua Yu <fenghua.yu@intel.com>, x86@kernel.org,
        Dave Hansen <dave.hansen@linux.intel.com>,
        Dan Williams <dan.j.williams@intel.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-nvdimm@lists.01.org, linux-fsdevel@vger.kernel.org,
        linux-mm@kvack.org, linux-kselftest@vger.kernel.org
Subject: Re: [PATCH RFC V3 5/9] x86/pks: Add PKS kernel API
Message-ID: <20201017054216.GB3702775@iweiny-DESK2.sc.intel.com>
References: <20201009194258.3207172-1-ira.weiny@intel.com>
 <20201009194258.3207172-6-ira.weiny@intel.com>
 <20201016110747.GM2611@hirez.programming.kicks-ass.net>
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On Fri, Oct 16, 2020 at 01:07:47PM +0200, Peter Zijlstra wrote:
> On Fri, Oct 09, 2020 at 12:42:54PM -0700, ira.weiny@intel.com wrote:
> > +static inline void pks_update_protection(int pkey, unsigned long protection)
> > +{
> > +	current->thread.saved_pkrs = update_pkey_val(current->thread.saved_pkrs,
> > +						     pkey, protection);
> > +	preempt_disable();
> > +	write_pkrs(current->thread.saved_pkrs);
> > +	preempt_enable();
> > +}
> 
> write_pkrs() already disables preemption itself. Wrapping it in yet
> another layer is useless.

I was thinking the update to saved_pkrs needed this protection as well and that
was to be included in the preemption disable.  But that too is incorrect.

I've removed this preemption disable.

Thanks,
Ira