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

Thomas Gleixner
2023-03-01T21:07:58Z

Miquel!

On Wed, Mar 01 2023 at 11:55, Miquel Raynal wrote:
> tglx@linutronix.de 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.

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

Untested workaround below. I hate it with a passion, but *shrug*.

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(-)

--- 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