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Message-ID: <1494933722.21847.47.camel@kernel.crashing.org>
Subject: Re: [PATCH 1/3] powerpc: Add __hard_irqs_disabled()
From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>, paulus@samba.org,
 mpe@ellerman.id.au, Frederic Barrat <fbarrat@linux.vnet.ibm.com>
Cc: linuxppc-dev@lists.ozlabs.org
Date: Tue, 16 May 2017 21:22:02 +1000
In-Reply-To: <1494926782-25700-1-git-send-email-aneesh.kumar@linux.vnet.ibm.com>
References: <1494926782-25700-1-git-send-email-aneesh.kumar@linux.vnet.ibm.com>
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On Tue, 2017-05-16 at 14:56 +0530, Aneesh Kumar K.V wrote:
>  
> +static inline bool __hard_irqs_disabled(void)
> +{
> +       unsigned long flags = mfmsr();
> +       return (flags & MSR_EE) == 0;
> +}
> +

Reading the MSR has a cost. Can't we rely on paca->irq_happened being
non-0 ?

(If you are paranoid, add a test of msr as well and warn if there's
a mismatch ...)

Cheers,
Ben.