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Date:   Thu, 26 May 2022 08:30:21 -0700
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Subject: Re: [PATCH] x86/platform/uv: Dont use smp_processor_id while
 preemptable
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To:     Mike Travis <mike.travis@hpe.com>, Borislav Petkov <bp@alien8.de>,
        Dave Hansen <dave.hansen@linux.intel.com>,
        Ingo Molnar <mingo@redhat.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        Steve Wahl <steve.wahl@hpe.com>, x86@kernel.org
Cc:     Dimitri Sivanich <dimitri.sivanich@hpe.com>,
        Andy Shevchenko <andy@infradead.org>,
        Darren Hart <dvhart@infradead.org>,
        "H. Peter Anvin" <hpa@zytor.com>,
        Russ Anderson <russ.anderson@hpe.com>,
        linux-kernel@vger.kernel.org, platform-driver-x86@vger.kernel.org
References: <20220520203755.266337-1-mike.travis@hpe.com>
From:   Dave Hansen <dave.hansen@intel.com>
In-Reply-To: <20220520203755.266337-1-mike.travis@hpe.com>
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On 5/20/22 13:37, Mike Travis wrote:
> To avoid a "BUG: using smp_processor_id() in preemptible" debug
> warning message, disable preemption around use of the processor id.

I'm sure this gets rid of the warning.  But, could you please take a
quick look at the callers and ensure that they can handle if this read
comes from another CPU?

In other words, what would actually go wrong if uv_read_rtc() got
preempted in this region?  What would this actually fix?