[patch 02/10] genirq/msi: Use lock guards for MSI descriptor locking

Thomas Gleixner
2025-03-09T08:41:46Z

Provide a lock guard for MSI descriptor locking and update the core code
accordingly.

No functional change intended.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
---
include/linux/msi.h | 3 +
kernel/irq/msi.c | 104 +++++++++++++++++++---------------------------------
2 files changed, 42 insertions(+), 65 deletions(-)

--- a/include/linux/msi.h
+++ b/include/linux/msi.h
@@ -227,6 +227,9 @@ int msi_setup_device_data(struct device
void msi_lock_descs(struct device *dev);
void msi_unlock_descs(struct device *dev);

+DEFINE_LOCK_GUARD_1(msi_descs_lock, struct device, msi_lock_descs(_T->lock),
+ msi_unlock_descs(_T->lock));
+
struct msi_desc *msi_domain_first_desc(struct device *dev, unsigned int domid,
enum msi_desc_filter filter);

--- a/kernel/irq/msi.c
+++ b/kernel/irq/msi.c
@@ -443,7 +443,6 @@ EXPORT_SYMBOL_GPL(msi_next_desc);
unsigned int msi_domain_get_virq(struct device *dev, unsigned int domid, unsigned int index)
{
struct msi_desc *desc;
- unsigned int ret = 0;
bool pcimsi = false;
struct xarray *xa;

@@ -457,7 +456,7 @@ unsigned int msi_domain_get_virq(struct
if (dev_is_pci(dev) && domid == MSI_DEFAULT_DOMAIN)
pcimsi = to_pci_dev(dev)->msi_enabled;

- msi_lock_descs(dev);
+ guard(msi_descs_lock)(dev);
xa = &dev->msi.data->__domains[domid].store;
desc = xa_load(xa, pcimsi ? 0 : index);
if (desc && desc->irq) {
@@ -466,16 +465,12 @@ unsigned int msi_domain_get_virq(struct
* PCI-MSIX and platform MSI use a descriptor per
* interrupt.
*/
- if (pcimsi) {
- if (index < desc->nvec_used)
- ret = desc->irq + index;
- } else {
- ret = desc->irq;
- }
+ if (!pcimsi)
+ return desc->irq;
+ if (index < desc->nvec_used)
+ return desc->irq + index;
}
-
- msi_unlock_descs(dev);
- return ret;
+ return 0;
}
EXPORT_SYMBOL_GPL(msi_domain_get_virq);

@@ -1037,25 +1032,23 @@ bool msi_create_device_irq_domain(struct
if (msi_setup_device_data(dev))
goto free_fwnode;

- msi_lock_descs(dev);
-
- if (WARN_ON_ONCE(msi_get_device_domain(dev, domid)))
- goto fail;
-
- if (!pops->init_dev_msi_info(dev, parent, parent, &bundle->info))
- goto fail;
-
- domain = __msi_create_irq_domain(fwnode, &bundle->info, IRQ_DOMAIN_FLAG_MSI_DEVICE, parent);
- if (!domain)
- goto fail;
-
- domain->dev = dev;
- dev->msi.data->__domains[domid].domain = domain;
- msi_unlock_descs(dev);
- return true;
+ scoped_guard(msi_descs_lock, dev) {
+ if (WARN_ON_ONCE(msi_get_device_domain(dev, domid)))
+ goto free_fwnode;
+
+ if (!pops->init_dev_msi_info(dev, parent, parent, &bundle->info))
+ goto free_fwnode;
+
+ domain = __msi_create_irq_domain(fwnode, &bundle->info, IRQ_DOMAIN_FLAG_MSI_DEVICE,
+ parent);
+ if (!domain)
+ goto free_fwnode;
+
+ domain->dev = dev;
+ dev->msi.data->__domains[domid].domain = domain;
+ return true;
+ }

-fail:
- msi_unlock_descs(dev);
free_fwnode:
irq_domain_free_fwnode(fwnalloced);
free_bundle:
@@ -1074,12 +1067,10 @@ void msi_remove_device_irq_domain(struct
struct msi_domain_info *info;
struct irq_domain *domain;

- msi_lock_descs(dev);
-
+ guard(msi_descs_lock)(dev);
domain = msi_get_device_domain(dev, domid);
-
if (!domain || !irq_domain_is_msi_device(domain))
- goto unlock;
+ return;

dev->msi.data->__domains[domid].domain = NULL;
info = domain->host_data;
@@ -1088,9 +1079,6 @@ void msi_remove_device_irq_domain(struct
irq_domain_remove(domain);
irq_domain_free_fwnode(fwnode);
kfree(container_of(info, struct msi_domain_template, info));
-
-unlock:
- msi_unlock_descs(dev);
}

/**
@@ -1106,16 +1094,14 @@ bool msi_match_device_irq_domain(struct
{
struct msi_domain_info *info;
struct irq_domain *domain;
- bool ret = false;

- msi_lock_descs(dev);
+ guard(msi_descs_lock)(dev);
domain = msi_get_device_domain(dev, domid);
if (domain && irq_domain_is_msi_device(domain)) {
info = domain->host_data;
- ret = info->bus_token == bus_token;
+ return info->bus_token == bus_token;
}
- msi_unlock_descs(dev);
- return ret;
+ return false;
}

static int msi_domain_prepare_irqs(struct irq_domain *domain, struct device *dev,
@@ -1365,12 +1351,9 @@ int msi_domain_alloc_irqs_range(struct d
.last = last,
.nirqs = last + 1 - first,
};
- int ret;

- msi_lock_descs(dev);
- ret = msi_domain_alloc_locked(dev, &ctrl);
- msi_unlock_descs(dev);
- return ret;
+ guard(msi_descs_lock)(dev);
+ return msi_domain_alloc_locked(dev, &ctrl);
}
EXPORT_SYMBOL_GPL(msi_domain_alloc_irqs_range);

@@ -1474,12 +1457,8 @@ struct msi_map msi_domain_alloc_irq_at(s
const struct irq_affinity_desc *affdesc,
union msi_instance_cookie *icookie)
{
- struct msi_map map;
-
- msi_lock_descs(dev);
- map = __msi_domain_alloc_irq_at(dev, domid, index, affdesc, icookie);
- msi_unlock_descs(dev);
- return map;
+ guard(msi_descs_lock)(dev);
+ return __msi_domain_alloc_irq_at(dev, domid, index, affdesc, icookie);
}

/**
@@ -1516,13 +1495,11 @@ int msi_device_domain_alloc_wired(struct

icookie.value = ((u64)type << 32) | hwirq;

- msi_lock_descs(dev);
+ guard(msi_descs_lock)(dev);
if (WARN_ON_ONCE(msi_get_device_domain(dev, domid) != domain))
map.index = -EINVAL;
else
map = __msi_domain_alloc_irq_at(dev, domid, MSI_ANY_INDEX, NULL, &icookie);
- msi_unlock_descs(dev);
-
return map.index >= 0 ? map.virq : map.index;
}

@@ -1615,9 +1592,8 @@ static void msi_domain_free_irqs_range_l
void msi_domain_free_irqs_range(struct device *dev, unsigned int domid,
unsigned int first, unsigned int last)
{
- msi_lock_descs(dev);
+ guard(msi_descs_lock)(dev);
msi_domain_free_irqs_range_locked(dev, domid, first, last);
- msi_unlock_descs(dev);
}
EXPORT_SYMBOL_GPL(msi_domain_free_irqs_all);

@@ -1647,9 +1623,8 @@ void msi_domain_free_irqs_all_locked(str
*/
void msi_domain_free_irqs_all(struct device *dev, unsigned int domid)
{
- msi_lock_descs(dev);
+ guard(msi_descs_lock)(dev);
msi_domain_free_irqs_all_locked(dev, domid);
- msi_unlock_descs(dev);
}

/**
@@ -1668,12 +1643,11 @@ void msi_device_domain_free_wired(struct
if (WARN_ON_ONCE(!dev || !desc || domain->bus_token != DOMAIN_BUS_WIRED_TO_MSI))
return;

- msi_lock_descs(dev);
- if (!WARN_ON_ONCE(msi_get_device_domain(dev, MSI_DEFAULT_DOMAIN) != domain)) {
- msi_domain_free_irqs_range_locked(dev, MSI_DEFAULT_DOMAIN, desc->msi_index,
- desc->msi_index);
- }
- msi_unlock_descs(dev);
+ guard(msi_descs_lock)(dev);
+ if (WARN_ON_ONCE(msi_get_device_domain(dev, MSI_DEFAULT_DOMAIN) != domain))
+ return;
+ msi_domain_free_irqs_range_locked(dev, MSI_DEFAULT_DOMAIN, desc->msi_index,
+ desc->msi_index);
}

/**