Re: [PATCH v11 23/23] CXL/PCI: Disable CXL protocol error interrupts during CXL Port cleanup

[Gregory Price <gourry@gourry.net>]

Hi Terry,

On Tue, Aug 26, 2025 at 08:35:38PM -0500, Terry Bowman wrote:
> Introduce cxl_mask_proto_interrupts() to call pci_aer_mask_internal_errors().
> Add calls to cxl_mask_proto_interrupts() within CXL Port teardown for CXL
> Root Ports, CXL Downstream Switch Ports, CXL Upstream Switch Ports, and CXL
> Endpoints. Follow the same "bottom-up" approach used during CXL Port
> teardown.
> 
...
> @@ -1471,6 +1475,8 @@ static void cxl_detach_ep(void *data)
>  {
>  	struct cxl_memdev *cxlmd = data;
>  
> +	cxl_mask_proto_interrupts(cxlmd->cxlds->dev);
> +
>  	for (int i = cxlmd->depth - 1; i >= 1; i--) {
>  		struct cxl_port *port, *parent_port;
>  		struct detach_ctx ctx = {

While testing v10 of this patch set, we found ourselves with a deadlock
on boot with the following stack in the hung task:

[  252.784440]  <TASK>
[  252.789090]  schedule+0x5d6/0x1670
[  252.796629]  ? schedule_preempt_disabled+0xa/0x10
[  252.807061]  schedule_preempt_disabled+0xa/0x10
[  252.817108]  __mutex_lock+0x245/0x7b0
[  252.825229]  cxl_mask_proto_interrupts+0x23/0x50
[  252.835470]  cxl_detach_ep+0x25/0x2e0

This occurs on a system which fails to probe ports fully due to the
duplicate id error resolved by the Delayed HB patch set.  

But it's concerning that there's a deadlock condition without that
patch set. Can you help try to eyeball this?  I'm trying to get more
debug info, but testing system availability is limited.

~Gregory