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Date:   Mon, 3 Jun 2019 17:25:34 +0100
From:   Catalin Marinas <catalin.marinas@arm.com>
To:     Julien Grall <julien.grall@arm.com>
Cc:     linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
        kvmarm@lists.cs.columbia.edu, will.deacon@arm.com,
        christoffer.dall@arm.com, marc.zyngier@arm.com,
        james.morse@arm.com, julien.thierry@arm.com,
        suzuki.poulose@arm.com, Dave.Martin@arm.com,
        ard.biesheuvel@linaro.org
Subject: Re: [PATCH v5 3/3] arm64/fpsimd: Don't disable softirq when touching
 FPSIMD/SVE state
Message-ID: <20190603162534.GF63283@arrakis.emea.arm.com>
References: <20190521172139.21277-1-julien.grall@arm.com>
 <20190521172139.21277-4-julien.grall@arm.com>
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On Tue, May 21, 2019 at 06:21:39PM +0100, Julien Grall wrote:
> Since a softirq is supposed to check may_use_simd() anyway before
> attempting to use FPSIMD/SVE, there is limited reason to keep softirq
> disabled when touching the FPSIMD/SVE context. Instead, we can simply
> disable preemption and mark the FPSIMD/SVE context as in use by setting
> CPU's fpsimd_context_busy flag.
[...]
> +static void get_cpu_fpsimd_context(void)
> +{
> +	preempt_disable();
> +	__get_cpu_fpsimd_context();
> +}

Is there anything that prevents a softirq being invoked between
preempt_disable() and __get_cpu_fpsimd_context()?

-- 
Catalin