On 16/08/16 03:15, Zheng, Lv wrote:
Hi,
From: linux-acpi-owner@vger.kernel.org [mailto:linux-acpi-owner@vger.kernel.org] On Behalf Of Lorenzo Pieralisi Subject: Re: [PATCH V8 2/8] ACPI: Add new IORT functions to support MSI domain handling
On Thu, Aug 11, 2016 at 12:06:32PM +0200, Tomasz Nowicki wrote:
[...]
+/**
- iort_register_domain_token() - register domain token and related ITS ID
- to the list from where we can get it back later on.
- @trans_id: ITS ID.
- @fw_node: Domain token.
- Returns: 0 on success, -ENOMEM if no memory when allocating list element
- */
+int iort_register_domain_token(int trans_id, struct fwnode_handle *fw_node) +{
- struct iort_its_msi_chip *its_msi_chip;
- its_msi_chip = kzalloc(sizeof(*its_msi_chip), GFP_KERNEL);
I spotted this while reworking my ARM SMMU series, this may sleep and that's no good given that we call it within the acpi_probe_lock.
Same goes for irq_domain_alloc_fwnode() (that we call in gic_v2_acpi_init()), we have got to fix this usage, I will see with Marc what's the best way to do it.
If we can ensure that all table device probe entries are created during link stage or early stage. I think you can safely unlock probe lock before invoking acpi_table_parse() in __acpi_probe_device_table().
That'd be quite risky, as this lock is the only thing that protects the acpi_probe_entry pointer (I really wish the ACPI API was less global variable happy), and I don't see how we can guarantee to only ever execute this in a single-threaded environment.
An alternative would be to turn the spinlock into a mutex, which will allow sleeping, and yet provide the required mutual exclusion.
Thanks,
M.