[patch V4 02/14] genirq/msi: Use lock guards for MSI descriptor locking

Thomas Gleixner
2025-03-19T10:56:41Z

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>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

---
V2: Remove the gotos - Jonathan
---
include/linux/irqdomain.h | 2
include/linux/msi.h | 3 +
kernel/irq/msi.c | 109 ++++++++++++++++------------------------------
3 files changed, 45 insertions(+), 69 deletions(-)

--- a/include/linux/irqdomain.h
+++ b/include/linux/irqdomain.h
@@ -281,6 +281,8 @@ static inline struct fwnode_handle *irq_

void irq_domain_free_fwnode(struct fwnode_handle *fwnode);

+DEFINE_FREE(irq_domain_free_fwnode, struct fwnode_handle *, if (_T) irq_domain_free_fwnode(_T))
+
struct irq_domain_chip_generic_info;

/**
--- 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);

@@ -993,9 +988,8 @@ bool msi_create_device_irq_domain(struct
void *chip_data)
{
struct irq_domain *domain, *parent = dev->msi.domain;
- struct fwnode_handle *fwnode, *fwnalloced = NULL;
- struct msi_domain_template *bundle;
const struct msi_parent_ops *pops;
+ struct fwnode_handle *fwnode;

if (!irq_domain_is_msi_parent(parent))
return false;
@@ -1003,7 +997,8 @@ bool msi_create_device_irq_domain(struct
if (domid >= MSI_MAX_DEVICE_IRQDOMAINS)
return false;

- bundle = kmemdup(template, sizeof(*bundle), GFP_KERNEL);
+ struct msi_domain_template *bundle __free(kfree) =
+ kmemdup(template, sizeof(*bundle), GFP_KERNEL);
if (!bundle)
return false;

@@ -1026,41 +1021,36 @@ bool msi_create_device_irq_domain(struct
* node as they are not guaranteed to have a fwnode. They are never
* looked up and always handled in the context of the device.
*/
- if (bundle->info.flags & MSI_FLAG_USE_DEV_FWNODE)
- fwnode = dev->fwnode;
+ struct fwnode_handle *fwnode_alloced __free(irq_domain_free_fwnode) = NULL;
+
+ if (!(bundle->info.flags & MSI_FLAG_USE_DEV_FWNODE))
+ fwnode = fwnode_alloced = irq_domain_alloc_named_fwnode(bundle->name);
else
- fwnode = fwnalloced = irq_domain_alloc_named_fwnode(bundle->name);
+ fwnode = dev->fwnode;

if (!fwnode)
- goto free_bundle;
+ return false;

if (msi_setup_device_data(dev))
- goto free_fwnode;
-
- msi_lock_descs(dev);
+ return false;

+ guard(msi_descs_lock)(dev);
if (WARN_ON_ONCE(msi_get_device_domain(dev, domid)))
- goto fail;
+ return false;

if (!pops->init_dev_msi_info(dev, parent, parent, &bundle->info))
- goto fail;
+ return false;

domain = __msi_create_irq_domain(fwnode, &bundle->info, IRQ_DOMAIN_FLAG_MSI_DEVICE, parent);
if (!domain)
- goto fail;
+ return false;

+ /* @bundle and @fwnode_alloced are now in use. Prevent cleanup */
+ retain_ptr(bundle);
+ retain_ptr(fwnode_alloced);
domain->dev = dev;
dev->msi.data->__domains[domid].domain = domain;
- msi_unlock_descs(dev);
return true;
-
-fail:
- msi_unlock_descs(dev);
-free_fwnode:
- irq_domain_free_fwnode(fwnalloced);
-free_bundle:
- kfree(bundle);
- return false;
}

/**
@@ -1074,12 +1064,10 @@ 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 +1076,6 @@ 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 +1091,14 @@ 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 +1348,9 @@ 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 +1454,8 @@ 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 +1492,11 @@ 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 +1589,8 @@ 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 +1620,8 @@ 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 +1640,11 @@ 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);
}

/**