Subject: Re: [patch 05/39] genirq/msi: Remove filter from msi_free_descs_free_range()

From: Miquel Raynal <[email-masked]>
Date: Thu, 2 Mar 2023 15:43:18 +0100

Hi Thomas,

[email-masked] wrote on Wed, 01 Mar 2023 22:07:48 +0100:

> Miquel!
> 
> On Wed, Mar 01 2023 at 11:55, Miquel Raynal wrote:
> > [email-masked] wrote on Fri, 11 Nov 2022 14:54:22 +0100 (CET):
> >  
> >> When a range of descriptors is freed then all of them are not associated to
> >> a linux interrupt. Remove the filter and add a warning to the free function.
> >> +		/* Leak the descriptor when it is still referenced */
> >> +		if (WARN_ON_ONCE(msi_desc_match(desc, MSI_DESC_ASSOCIATED)))
> >> +			continue;
> >> +		msi_free_desc(desc);
> >>  	}
> >>  }  
> >
> > It looks like since this commit I am getting warnings upon EPROBE_DEFER
> > errors in the mvpp2 Marvell Ethernet driver. I looked a bit at the
> > internals to understand why this warning was shown, and it seems that
> > nothing "de-references" the descriptors, which would mean here:
> > resetting desc->irq to 0.  
> 
> Correct. This platform-msi ^(*&!@&^ hack really needs to die ASAP.

:-)

> Marc, where are we on that? Is this still in limbo?
> 
> > I am wondering how useful thisd WARN_ON() is, or otherwise where the  
> 
> It is useful as it caught bugs already.

Sure.

> > desc->irq entry should be zeroed (if I understand that correctly), any
> > help will be appreciated.  
> 
> Untested workaround below.

Excellent!

> I hate it with a passion, but *shrug*.

:'D

> Thanks,
> 
>         tglx
> ---
>  drivers/base/platform-msi.c |    1 +
>  include/linux/msi.h         |    2 ++
>  kernel/irq/msi.c            |   23 ++++++++++++++++++++++-
>  3 files changed, 25 insertions(+), 1 deletion(-)

Kudos for the diff, which indeed works perfectly in my case. I guess
you'll make a proper patch soon, if that's the case you can add my:

Tested-by: Miquel Raynal <[email-masked]>

Let me know otherwise.

Thanks a lot for the very quick fix!
Miquèl

> --- a/drivers/base/platform-msi.c
> +++ b/drivers/base/platform-msi.c
> @@ -324,6 +324,7 @@ void platform_msi_device_domain_free(str
>  	struct platform_msi_priv_data *data = domain->host_data;
>  
>  	msi_lock_descs(data->dev);
> +	msi_domain_depopulate_descs(data->dev, virq, nr_irqs);
>  	irq_domain_free_irqs_common(domain, virq, nr_irqs);
>  	msi_free_msi_descs_range(data->dev, virq, virq + nr_irqs - 1);
>  	msi_unlock_descs(data->dev);
> --- a/include/linux/msi.h
> +++ b/include/linux/msi.h
> @@ -631,6 +631,8 @@ int msi_domain_prepare_irqs(struct irq_d
>  			    int nvec, msi_alloc_info_t *args);
>  int msi_domain_populate_irqs(struct irq_domain *domain, struct device *dev,
>  			     int virq, int nvec, msi_alloc_info_t *args);
> +void msi_domain_depopulate_descs(struct device *dev, int virq, int nvec);
> +
>  struct irq_domain *
>  __platform_msi_create_device_domain(struct device *dev,
>  				    unsigned int nvec,
> --- a/kernel/irq/msi.c
> +++ b/kernel/irq/msi.c
> @@ -1109,14 +1109,35 @@ int msi_domain_populate_irqs(struct irq_
>  	return 0;
>  
>  fail:
> -	for (--virq; virq >= virq_base; virq--)
> +	for (--virq; virq >= virq_base; virq--) {
> +		msi_domain_depopulate_descs(dev, virq, 1);
>  		irq_domain_free_irqs_common(domain, virq, 1);
> +	}
>  	msi_domain_free_descs(dev, &ctrl);
>  unlock:
>  	msi_unlock_descs(dev);
>  	return ret;
>  }
>  
> +void msi_domain_depopulate_descs(struct device *dev, int virq_base, int nvec)
> +{
> +	struct msi_ctrl ctrl = {
> +		.domid	= MSI_DEFAULT_DOMAIN,
> +		.first  = virq_base,
> +		.last	= virq_base + nvec - 1,
> +	};
> +	struct msi_desc *desc;
> +	struct xarray *xa;
> +	unsigned long idx;
> +
> +	if (!msi_ctrl_valid(dev, &ctrl))
> +		return;
> +
> +	xa = &dev->msi.data->__domains[ctrl.domid].store;
> +	xa_for_each_range(xa, idx, desc, ctrl.first, ctrl.last)
> +		desc->irq = 0;
> +}
> +
>  /*
>   * Carefully check whether the device can use reservation mode. If
>   * reservation mode is enabled then the early activation will assign a