linux-kernel - Re: [PATCH v5 7/7] iommu/riscv: Paging domain support

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Message-ID: <20240522-b25680db03b547123f1cd59a@orel>
Date: Wed, 22 May 2024 10:07:14 +0200
From: Andrew Jones <ajones@...tanamicro.com>
To: Tomasz Jeznach <tjeznach@...osinc.com>
Cc: Joerg Roedel <joro@...tes.org>, Will Deacon <will@...nel.org>, 
	Robin Murphy <robin.murphy@....com>, Paul Walmsley <paul.walmsley@...ive.com>, 
	Anup Patel <apatel@...tanamicro.com>, devicetree@...r.kernel.org, Conor Dooley <conor+dt@...nel.org>, 
	Albert Ou <aou@...s.berkeley.edu>, linux@...osinc.com, linux-kernel@...r.kernel.org, 
	Rob Herring <robh+dt@...nel.org>, Sebastien Boeuf <seb@...osinc.com>, iommu@...ts.linux.dev, 
	Palmer Dabbelt <palmer@...belt.com>, Nick Kossifidis <mick@....forth.gr>, 
	Krzysztof Kozlowski <krzk+dt@...nel.org>, linux-riscv@...ts.infradead.org, 
	Lu Baolu <baolu.lu@...ux.intel.com>
Subject: Re: [PATCH v5 7/7] iommu/riscv: Paging domain support

On Tue, May 14, 2024 at 11:16:19AM GMT, Tomasz Jeznach wrote:
..
> +static int riscv_iommu_bond_link(struct riscv_iommu_domain *domain,
> +				 struct device *dev)
> +{
> +	struct riscv_iommu_device *iommu = dev_to_iommu(dev);
> +	struct riscv_iommu_bond *bond;
> +	struct list_head *bonds;
> +
> +	bond = kzalloc(sizeof(*bond), GFP_KERNEL);
> +	if (!bond)
> +		return -ENOMEM;
> +	bond->dev = dev;
> +
> +	/*
> +	 * List of devices attached to the domain is arranged based on
> +	 * managed IOMMU device.
> +	 */
> +
> +	spin_lock(&domain->lock);
> +	list_for_each_rcu(bonds, &domain->bonds)
> +		if (dev_to_iommu(list_entry(bonds, struct riscv_iommu_bond, list)->dev) == iommu)
> +			break;

We should wrap this list_for_each_rcu() in rcu_read_lock() and
rcu_read_unlock().

Thanks,
drew

> +	list_add_rcu(&bond->list, bonds);
> +	spin_unlock(&domain->lock);
> +
> +	/* Synchronize with riscv_iommu_iotlb_inval() sequence. See comment below. */
> +	smp_mb();
> +
> +	return 0;
> +}