Re: [PATCH 5/5] iommu/arm-smmu-v3: Add Context Descriptor display to debugfs

[Nicolin Chen]

On Wed, May 20, 2026 at 02:37:11PM +0800, Qinxin Xia wrote:
> +static int smmu_debugfs_cd_show(struct seq_file *seq, void *unused)
> +{
> +	struct device *dev = seq->private;
> +	struct arm_smmu_master *master;
> +	u32 max_ssids, ssid;
> +
> +	guard(mutex)(&arm_smmu_asid_lock);
> +
> +	master = dev_iommu_priv_get(dev);
> +	if (!master) {
> +		seq_puts(seq, "No master data\n");
> +		return 0;
> +	}

arm_smmu_asid_lock fences against domain attachments, required
by CD (yes). But, it doesn't fence against a device unplug. So
this might need both streams_mutex and asid_lock.

Nicolin