linux-kernel - Re: [PATCH] irqchip/gic-v3: Use wmb() instead of smb_wmb() in gic_raise

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Date:   Fri, 18 Feb 2022 19:27:52 +0800
From:   Barry Song <21cnbao@...il.com>
To:     shankerd@...eaurora.org, will@...nel.org
Cc:     kvmarm@...ts.cs.columbia.edu, linux-arm-kernel@...ts.infradead.org,
        linux-kernel@...r.kernel.org, marc.zyngier@....com,
        scampbel@...eaurora.org, tglx@...utronix.de,
        tspeier@...eaurora.org, vikrams@...eaurora.org
Subject: Re: [PATCH] irqchip/gic-v3: Use wmb() instead of smb_wmb() in gic_raise_softirq()

> --- a/drivers/irqchip/irq-gic-v3.c
> +++ b/drivers/irqchip/irq-gic-v3.c
> @@ -688,7 +688,7 @@ static void gic_raise_softirq(const struct cpumask *mask, unsigned int irq)
>  	 * Ensure that stores to Normal memory are visible to the
>  	 * other CPUs before issuing the IPI.
>  	 */
> -	smp_wmb();
> +	wmb();

Sorry for waking up the old thread. isn't dsb(ishst) enough here as we only
need to guarantee the visibility of data to other CPUs in smp inner domain
before we send the ipi?

> 
>  	for_each_cpu(cpu, mask) {
>  		u64 cluster_id = MPIDR_TO_SGI_CLUSTER_ID(cpu_logical_map(cpu));

Thanks
Barry