Re: [REGRESSION] Re: [patch V3 09/33] genirq/msi: Add range checking to msi_insert_desc()

[Thomas Gleixner]

On Mon, Feb 20 2023 at 17:11, Russell King wrote:
> On Fri, Nov 25, 2022 at 12:25:59AM +0100, Thomas Gleixner wrote:
> Hi Thomas,
>
> This patch appears to cause a regression on Macchiatobin, delaying the
> boot by about ten seconds due to all the warnings the kernel now
> produces.
>
>> @@ -136,11 +149,16 @@ static bool msi_desc_match(struct msi_de
>>  
>>  static bool msi_ctrl_valid(struct device *dev, struct msi_ctrl *ctrl)
>>  {
>> +	unsigned int hwsize;
>> +
>>  	if (WARN_ON_ONCE(ctrl->domid >= MSI_MAX_DEVICE_IRQDOMAINS ||
>> -			 !dev->msi.data->__domains[ctrl->domid].domain ||
>> -			 ctrl->first > ctrl->last ||
>> -			 ctrl->first > MSI_MAX_INDEX ||
>> -			 ctrl->last > MSI_MAX_INDEX))
>> +			 !dev->msi.data->__domains[ctrl->domid].domain))
>> +		return false;
>> +
>> +	hwsize = msi_domain_get_hwsize(dev, ctrl->domid);
>
> This calls msi_get_device_domain() without taking dev->msi.data->mutex,
> resulting in the lockdep_assert_held() firing for what seems to be every
> MSI created by the Armada 8040 ICU driver, which suggests something isn't
> taking the lock as you expect. Please can you take a look and propose a
> patch to fix this regression.

Groan. I'll have a look.