[RFC PATCH 08/14] PCI/sysfs: migrate to device_sysfs_entry, defer physfn symlink
Pavol Sakac
sakacpav at amazon.de
Thu Jul 2 10:51:08 PDT 2026
Migrate PCI's per-device sysfs to the declarative walker, and as
part of that wire the bus/type dispatch chain via two new struct
device_type hooks.
- struct device_type grows .populate / .populate_all hooks
consulted by device_ktype_populate_one /
device_ktype_populate_all when the driver-core walker returns
-ENOENT.
- PCI's bus/type-owned per-device sysfs content (resource%u /
resource%u_wc files plus the physfn back-symlink) becomes
pci_sysfs_entries[] and is dispatched by the same walker.
- Lazy populate skips eager pci_create_sysfs_dev_files() so VFs
materialise their resource files only on first userspace
access.
The physfn symlink moves from per-device add to the wildcard row
on the VF; eager devices still see no change. Idempotent
re-creation is required by the VF lookup-then-readdir VFS order;
sysfs_kn_exists() provides the existence check.
No userspace ABI change.
Cc: Bjorn Helgaas <bhelgaas at google.com>
Cc: linux-pci at vger.kernel.org
Cc: linux-kernel at vger.kernel.org
Cc: Greg Kroah-Hartman <gregkh at linuxfoundation.org>
Cc: Danilo Krummrich <dakr at kernel.org>
Cc: driver-core at lists.linux.dev
Cc: Rafael J. Wysocki <rafael at kernel.org>
Cc: linux-api at vger.kernel.org
Assisted-by: Claude:claude-opus-4.7
Signed-off-by: Pavol Sakac <sakacpav at amazon.de>
---
drivers/base/core.c | 10 ++-
drivers/pci/iov.c | 5 --
drivers/pci/pci-sysfs.c | 149 ++++++++++++++++++++++++++++++++++++----
drivers/pci/pci.h | 5 ++
drivers/pci/probe.c | 4 +-
include/linux/device.h | 32 ++++++---
6 files changed, 175 insertions(+), 30 deletions(-)
diff --git a/drivers/base/core.c b/drivers/base/core.c
index 15a2dcf922d4b..6c5d1bb66c8f4 100644
--- a/drivers/base/core.c
+++ b/drivers/base/core.c
@@ -2811,9 +2811,9 @@ device_sysfs_entries_end(const struct device_sysfs_entry *entries)
return e;
}
-static int device_sysfs_apply(struct device *dev,
- const struct device_sysfs_entry *entries,
- enum dev_sysfs_action action, const char *name)
+int device_sysfs_apply(struct device *dev,
+ const struct device_sysfs_entry *entries,
+ enum dev_sysfs_action action, const char *name)
{
const struct device_sysfs_entry *e;
@@ -2983,6 +2983,8 @@ static int device_ktype_populate_one(struct kobject *kobj, const char *name)
}
ret = device_sysfs_apply(dev, ktype ? ktype->entries : NULL,
DEV_SYSFS_ADD_ONE, name);
+ if (ret == -ENOENT && dev->type && dev->type->populate)
+ ret = dev->type->populate(dev, name);
out:
mutex_unlock(&dev->sysfs_lazy->lock);
return ret;
@@ -3011,6 +3013,8 @@ static void device_ktype_populate_all(struct kobject *kobj)
device_sysfs_apply(dev, ktype ? ktype->entries : NULL,
DEV_SYSFS_ADD_ALL, NULL);
+ if (dev->type && dev->type->populate_all)
+ dev->type->populate_all(dev);
device_sysfs_set_populated(dev);
diff --git a/drivers/pci/iov.c b/drivers/pci/iov.c
index 91ac4e37ecb9c..ec2fca8209593 100644
--- a/drivers/pci/iov.c
+++ b/drivers/pci/iov.c
@@ -212,16 +212,11 @@ int pci_iov_sysfs_link(struct pci_dev *dev,
rc = sysfs_create_link(&dev->dev.kobj, &virtfn->dev.kobj, buf);
if (rc)
goto failed;
- rc = sysfs_create_link(&virtfn->dev.kobj, &dev->dev.kobj, "physfn");
- if (rc)
- goto failed1;
kobject_uevent(&virtfn->dev.kobj, KOBJ_CHANGE);
return 0;
-failed1:
- sysfs_remove_link(&dev->dev.kobj, buf);
failed:
return rc;
}
diff --git a/drivers/pci/pci-sysfs.c b/drivers/pci/pci-sysfs.c
index d37860841260c..5a779ebaee326 100644
--- a/drivers/pci/pci-sysfs.c
+++ b/drivers/pci/pci-sysfs.c
@@ -1247,6 +1247,13 @@ static int pci_create_attr(struct pci_dev *pdev, int num, int write_combine)
res_attr->attr.mode = 0600;
res_attr->size = pci_resource_len(pdev, num);
res_attr->private = (void *)(unsigned long)num;
+
+ /* Idempotent: skip if a concurrent populate already created this slot. */
+ if (sysfs_kn_exists(&pdev->dev.kobj, res_attr->attr.name)) {
+ kfree(res_attr);
+ return 0;
+ }
+
retval = sysfs_create_bin_file(&pdev->dev.kobj, res_attr);
if (retval) {
kfree(res_attr);
@@ -1264,8 +1271,6 @@ static int pci_create_attr(struct pci_dev *pdev, int num, int write_combine)
/**
* pci_create_resource_files - create resource files in sysfs for @dev
* @pdev: dev in question
- *
- * Walk the resources in @pdev creating files for each resource available.
*/
static int pci_create_resource_files(struct pci_dev *pdev)
{
@@ -1283,21 +1288,65 @@ static int pci_create_resource_files(struct pci_dev *pdev)
if (!pci_resource_len(pdev, i))
continue;
- retval = pci_create_attr(pdev, i, 0);
+ /* Skip slots already materialised by populate_one(). */
+ if (!pdev->res_attr[i]) {
+ retval = pci_create_attr(pdev, i, 0);
+ if (retval) {
+ pci_remove_resource_files(pdev);
+ return retval;
+ }
+ }
/* for prefetchable resources, create a WC mappable file */
- if (!retval && arch_can_pci_mmap_wc() &&
- pdev->resource[i].flags & IORESOURCE_PREFETCH)
+ if (arch_can_pci_mmap_wc() &&
+ pdev->resource[i].flags & IORESOURCE_PREFETCH &&
+ !pdev->res_attr_wc[i]) {
retval = pci_create_attr(pdev, i, 1);
- if (retval) {
- pci_remove_resource_files(pdev);
- return retval;
+ if (retval) {
+ pci_remove_resource_files(pdev);
+ return retval;
+ }
}
}
return 0;
}
+
+/*
+ * Resolve "resourceN" / "resourceN_wc" and create the single file.
+ * Returns -ENOENT for unrelated names or out-of-range/empty BARs so
+ * the walker continues to the next entry.
+ */
+static int pci_create_resource_file_by_name(struct pci_dev *pdev,
+ const char *name)
+{
+ unsigned int num;
+ int wc = 0;
+ int n = 0;
+
+ if (sscanf(name, "resource%u%n", &num, &n) != 1)
+ return -ENOENT;
+ if (name[n]) {
+ if (strcmp(name + n, "_wc"))
+ return -ENOENT;
+ wc = 1;
+ }
+
+ if (num >= PCI_STD_NUM_BARS || !pci_resource_len(pdev, num))
+ return -ENOENT;
+
+ if (wc && (!arch_can_pci_mmap_wc() ||
+ !(pdev->resource[num].flags & IORESOURCE_PREFETCH)))
+ return -ENOENT;
+
+ return pci_create_attr(pdev, num, wc);
+}
#else /* !(defined(HAVE_PCI_MMAP) || defined(ARCH_GENERIC_PCI_MMAP_RESOURCE)) */
int __weak pci_create_resource_files(struct pci_dev *dev) { return 0; }
void __weak pci_remove_resource_files(struct pci_dev *dev) { return; }
+static int pci_create_resource_file_by_name(struct pci_dev *pdev,
+ const char *name)
+{
+ return -ENOENT;
+}
#endif
/**
@@ -1661,26 +1710,88 @@ static const struct attribute_group pci_dev_resource_resize_group = {
.is_visible = resource_resize_is_visible,
};
+/* Per-device PCI sysfs catalogue. */
+
+/* physfn back-symlink - SR-IOV VF only. */
+
+#ifdef CONFIG_PCI_IOV
+
+static bool pci_applies_to_virtfn(struct device *dev)
+{
+ return to_pci_dev(dev)->is_virtfn;
+}
+
+static int pci_create_physfn_link(struct device *dev, const char *name)
+{
+ struct pci_dev *pdev = to_pci_dev(dev);
+
+ if (device_is_sysfs_lazy(dev))
+ lockdep_assert_held(&dev->sysfs_lazy->lock);
+
+ if (sysfs_kn_exists(&dev->kobj, "physfn"))
+ return 0;
+
+ return sysfs_create_link(&dev->kobj, &pdev->physfn->dev.kobj, "physfn");
+}
+
+#endif /* CONFIG_PCI_IOV */
+
+/* resource%u[_wc] family - wildcard row, create() dispatches on @name. */
+
+static int pci_create_resource(struct device *dev, const char *name)
+{
+ struct pci_dev *pdev = to_pci_dev(dev);
+
+ if (device_is_sysfs_lazy(dev))
+ lockdep_assert_held(&dev->sysfs_lazy->lock);
+
+ if (!name)
+ return pci_create_resource_files(pdev);
+
+ return pci_create_resource_file_by_name(pdev, name);
+}
+
+static void pci_remove_resource(struct device *dev)
+{
+ pci_remove_resource_files(to_pci_dev(dev));
+}
+
+static const struct device_sysfs_entry pci_sysfs_entries[] = {
+#ifdef CONFIG_PCI_IOV
+ {
+ .name = "physfn",
+ .applies_to = pci_applies_to_virtfn,
+ .create = pci_create_physfn_link,
+ },
+#endif
+ {
+ /* wildcard: "resource%u" / "resource%u_wc" family */
+ .create = pci_create_resource,
+ .remove = pci_remove_resource,
+ },
+ { }, /* sentinel: .create == NULL */
+};
+
int __must_check pci_create_sysfs_dev_files(struct pci_dev *pdev)
{
if (!sysfs_initialized)
return -EACCES;
- return pci_create_resource_files(pdev);
+ return device_sysfs_apply(&pdev->dev, pci_sysfs_entries,
+ DEV_SYSFS_ADD_ALL, NULL);
}
/**
- * pci_remove_sysfs_dev_files - cleanup PCI specific sysfs files
+ * pci_remove_sysfs_dev_files - cleanup PCI sysfs files for @pdev
* @pdev: device whose entries we should free
- *
- * Cleanup when @pdev is removed from sysfs.
*/
void pci_remove_sysfs_dev_files(struct pci_dev *pdev)
{
if (!sysfs_initialized)
return;
- pci_remove_resource_files(pdev);
+ device_sysfs_apply(&pdev->dev, pci_sysfs_entries,
+ DEV_SYSFS_REMOVE_ALL, NULL);
}
static int __init pci_sysfs_init(void)
@@ -1835,3 +1946,15 @@ const struct attribute_group *pci_dev_attr_groups[] = {
#endif
NULL,
};
+
+int pci_dev_type_populate_one(struct device *dev, const char *name)
+{
+ return device_sysfs_apply(dev, pci_sysfs_entries,
+ DEV_SYSFS_ADD_ONE, name);
+}
+
+void pci_dev_type_populate_all(struct device *dev)
+{
+ device_sysfs_apply(dev, pci_sysfs_entries,
+ DEV_SYSFS_ADD_ALL, NULL);
+}
diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h
index 4a14f88e543a2..9c884a158184c 100644
--- a/drivers/pci/pci.h
+++ b/drivers/pci/pci.h
@@ -395,6 +395,8 @@ static inline int pci_no_d1d2(struct pci_dev *dev)
#ifdef CONFIG_SYSFS
int pci_create_sysfs_dev_files(struct pci_dev *pdev);
void pci_remove_sysfs_dev_files(struct pci_dev *pdev);
+int pci_dev_type_populate_one(struct device *dev, const char *name);
+void pci_dev_type_populate_all(struct device *dev);
extern const struct attribute_group *pci_dev_groups[];
extern const struct attribute_group *pci_dev_attr_groups[];
extern const struct attribute_group *pcibus_groups[];
@@ -403,6 +405,9 @@ extern const struct attribute_group pci_doe_sysfs_group;
#else
static inline int pci_create_sysfs_dev_files(struct pci_dev *pdev) { return 0; }
static inline void pci_remove_sysfs_dev_files(struct pci_dev *pdev) { }
+static inline int pci_dev_type_populate_one(struct device *dev,
+ const char *name) { return -ENOENT; }
+static inline void pci_dev_type_populate_all(struct device *dev) { }
#define pci_dev_groups NULL
#define pci_dev_attr_groups NULL
#define pcibus_groups NULL
diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
index b63cd0c310bc0..ff7e6016c896f 100644
--- a/drivers/pci/probe.c
+++ b/drivers/pci/probe.c
@@ -2499,7 +2499,9 @@ static void pci_release_dev(struct device *dev)
}
static const struct device_type pci_dev_type = {
- .groups = pci_dev_attr_groups,
+ .groups = pci_dev_attr_groups,
+ .populate = pci_dev_type_populate_one,
+ .populate_all = pci_dev_type_populate_all,
};
struct pci_dev *pci_alloc_dev(struct pci_bus *bus)
diff --git a/include/linux/device.h b/include/linux/device.h
index c0a2ee429280c..948c3ea8055e5 100644
--- a/include/linux/device.h
+++ b/include/linux/device.h
@@ -118,14 +118,27 @@ struct device_sysfs_entry {
void (*remove)(struct device *dev);
};
-/*
- * The type of device, "struct device" is embedded in. A class
- * or bus can contain devices of different types
- * like "partitions" and "disks", "mouse" and "event".
- * This identifies the device type and carries type-specific
- * information, equivalent to the kobj_type of a kobject.
- * If "name" is specified, the uevent will contain it in
- * the DEVTYPE variable.
+int device_sysfs_apply(struct device *dev,
+ const struct device_sysfs_entry *entries,
+ enum dev_sysfs_action action, const char *name);
+
+/**
+ * struct device_type - The type of device, embedded in struct device.
+ * @name: if set, appears in the DEVTYPE uevent variable.
+ * @groups: attribute groups always present on devices of this type.
+ * @uevent: type-specific uevent handler (may set DEVTYPE or other).
+ * @devnode: populate /dev node metadata (mode, uid, gid).
+ * @release: release callback run after the last reference drops.
+ * @pm: dev_pm_ops vector for devices of this type.
+ * @populate: lazy ADD_ONE for type-owned synthetic attrs/symlinks.
+ * Called from kernfs populate; device_lock NOT held; may
+ * sleep. Returns -ENOENT for unknown names.
+ * @populate_all: readdir-time counterpart; best-effort, retry-safe.
+ *
+ * A class or bus can contain devices of different types like
+ * "partitions" and "disks", "mouse" and "event". This identifies
+ * the device type and carries type-specific information, equivalent
+ * to the kobj_type of a kobject.
*/
struct device_type {
const char *name;
@@ -136,6 +149,9 @@ struct device_type {
void (*release)(struct device *dev);
const struct dev_pm_ops *pm;
+
+ int (*populate)(struct device *dev, const char *name);
+ void (*populate_all)(struct device *dev);
};
/**
--
2.47.3
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