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Subject[PATCH v4 1/4] libnvdimm: register nvdimm_bus devices with an nd_bus driver
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A recent effort to add a new nvdimm bus provider attribute highlighted a
race between interrogating nvdimm_bus->nd_desc and nvdimm_bus tear down.
The typical way to handle these races is to take the device_lock() in
the attribute method and validate that the device is still active. In
order for a device to be 'active' it needs to be associated with a
driver. So, we create the small boilerplate for a driver and register
nvdimm_bus devices on the 'nvdimm_bus_type' bus.

A result of this change is that ndbusX devices now appear under
/sys/bus/nd/devices. In fact this makes /sys/class/nd somewhat
redundant, but removing that will need to take a long deprecation period
given its use by ndctl binaries in the field.

This change naturally pulls code from drivers/nvdimm/core.c to
drivers/nvdimm/bus.c, so it is a nice code organization clean-up as
well.

Cc: Vishal Verma <vishal.l.verma@intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
---
drivers/nvdimm/bus.c | 188 +++++++++++++++++++++++++++++++++++++++++++++++--
drivers/nvdimm/core.c | 127 ---------------------------------
2 files changed, 181 insertions(+), 134 deletions(-)

diff --git a/drivers/nvdimm/bus.c b/drivers/nvdimm/bus.c
index 275dd5c0a301..46d7e555b044 100644
--- a/drivers/nvdimm/bus.c
+++ b/drivers/nvdimm/bus.c
@@ -31,6 +31,7 @@
int nvdimm_major;
static int nvdimm_bus_major;
static struct class *nd_class;
+static DEFINE_IDA(nd_ida);

static int to_nd_device_type(struct device *dev)
{
@@ -60,13 +61,6 @@ static int nvdimm_bus_uevent(struct device *dev, struct kobj_uevent_env *env)
to_nd_device_type(dev));
}

-static int nvdimm_bus_match(struct device *dev, struct device_driver *drv)
-{
- struct nd_device_driver *nd_drv = to_nd_device_driver(drv);
-
- return !!test_bit(to_nd_device_type(dev), &nd_drv->type);
-}
-
static struct module *to_bus_provider(struct device *dev)
{
/* pin bus providers while regions are enabled */
@@ -223,6 +217,8 @@ long nvdimm_clear_poison(struct device *dev, phys_addr_t phys,
}
EXPORT_SYMBOL_GPL(nvdimm_clear_poison);

+static int nvdimm_bus_match(struct device *dev, struct device_driver *drv);
+
static struct bus_type nvdimm_bus_type = {
.name = "nd",
.uevent = nvdimm_bus_uevent,
@@ -232,6 +228,176 @@ static struct bus_type nvdimm_bus_type = {
.shutdown = nvdimm_bus_shutdown,
};

+static void nvdimm_bus_release(struct device *dev)
+{
+ struct nvdimm_bus *nvdimm_bus;
+
+ nvdimm_bus = container_of(dev, struct nvdimm_bus, dev);
+ ida_simple_remove(&nd_ida, nvdimm_bus->id);
+ kfree(nvdimm_bus);
+}
+
+static bool is_nvdimm_bus(struct device *dev)
+{
+ return dev->release == nvdimm_bus_release;
+}
+
+struct nvdimm_bus *walk_to_nvdimm_bus(struct device *nd_dev)
+{
+ struct device *dev;
+
+ for (dev = nd_dev; dev; dev = dev->parent)
+ if (is_nvdimm_bus(dev))
+ break;
+ dev_WARN_ONCE(nd_dev, !dev, "invalid dev, not on nd bus\n");
+ if (dev)
+ return to_nvdimm_bus(dev);
+ return NULL;
+}
+
+struct nvdimm_bus *to_nvdimm_bus(struct device *dev)
+{
+ struct nvdimm_bus *nvdimm_bus;
+
+ nvdimm_bus = container_of(dev, struct nvdimm_bus, dev);
+ WARN_ON(!is_nvdimm_bus(dev));
+ return nvdimm_bus;
+}
+EXPORT_SYMBOL_GPL(to_nvdimm_bus);
+
+struct nvdimm_bus *nvdimm_bus_register(struct device *parent,
+ struct nvdimm_bus_descriptor *nd_desc)
+{
+ struct nvdimm_bus *nvdimm_bus;
+ int rc;
+
+ nvdimm_bus = kzalloc(sizeof(*nvdimm_bus), GFP_KERNEL);
+ if (!nvdimm_bus)
+ return NULL;
+ INIT_LIST_HEAD(&nvdimm_bus->list);
+ INIT_LIST_HEAD(&nvdimm_bus->mapping_list);
+ INIT_LIST_HEAD(&nvdimm_bus->poison_list);
+ init_waitqueue_head(&nvdimm_bus->probe_wait);
+ nvdimm_bus->id = ida_simple_get(&nd_ida, 0, 0, GFP_KERNEL);
+ mutex_init(&nvdimm_bus->reconfig_mutex);
+ if (nvdimm_bus->id < 0) {
+ kfree(nvdimm_bus);
+ return NULL;
+ }
+ nvdimm_bus->nd_desc = nd_desc;
+ nvdimm_bus->dev.parent = parent;
+ nvdimm_bus->dev.release = nvdimm_bus_release;
+ nvdimm_bus->dev.groups = nd_desc->attr_groups;
+ nvdimm_bus->dev.bus = &nvdimm_bus_type;
+ dev_set_name(&nvdimm_bus->dev, "ndbus%d", nvdimm_bus->id);
+ rc = device_register(&nvdimm_bus->dev);
+ if (rc) {
+ dev_dbg(&nvdimm_bus->dev, "registration failed: %d\n", rc);
+ goto err;
+ }
+
+ return nvdimm_bus;
+ err:
+ put_device(&nvdimm_bus->dev);
+ return NULL;
+}
+EXPORT_SYMBOL_GPL(nvdimm_bus_register);
+
+void nvdimm_bus_unregister(struct nvdimm_bus *nvdimm_bus)
+{
+ if (!nvdimm_bus)
+ return;
+ device_unregister(&nvdimm_bus->dev);
+}
+EXPORT_SYMBOL_GPL(nvdimm_bus_unregister);
+
+static int child_unregister(struct device *dev, void *data)
+{
+ /*
+ * the singular ndctl class device per bus needs to be
+ * "device_destroy"ed, so skip it here
+ *
+ * i.e. remove classless children
+ */
+ if (dev->class)
+ /* pass */;
+ else
+ nd_device_unregister(dev, ND_SYNC);
+ return 0;
+}
+
+static void free_poison_list(struct list_head *poison_list)
+{
+ struct nd_poison *pl, *next;
+
+ list_for_each_entry_safe(pl, next, poison_list, list) {
+ list_del(&pl->list);
+ kfree(pl);
+ }
+ list_del_init(poison_list);
+}
+
+static int nd_bus_remove(struct device *dev)
+{
+ struct nvdimm_bus *nvdimm_bus = to_nvdimm_bus(dev);
+
+ mutex_lock(&nvdimm_bus_list_mutex);
+ list_del_init(&nvdimm_bus->list);
+ mutex_unlock(&nvdimm_bus_list_mutex);
+
+ nd_synchronize();
+ device_for_each_child(&nvdimm_bus->dev, NULL, child_unregister);
+
+ nvdimm_bus_lock(&nvdimm_bus->dev);
+ free_poison_list(&nvdimm_bus->poison_list);
+ nvdimm_bus_unlock(&nvdimm_bus->dev);
+
+ nvdimm_bus_destroy_ndctl(nvdimm_bus);
+
+ return 0;
+}
+
+static int nd_bus_probe(struct device *dev)
+{
+ struct nvdimm_bus *nvdimm_bus = to_nvdimm_bus(dev);
+ int rc;
+
+ rc = nvdimm_bus_create_ndctl(nvdimm_bus);
+ if (rc)
+ return rc;
+
+ mutex_lock(&nvdimm_bus_list_mutex);
+ list_add_tail(&nvdimm_bus->list, &nvdimm_bus_list);
+ mutex_unlock(&nvdimm_bus_list_mutex);
+
+ /* enable bus provider attributes to look up their local context */
+ dev_set_drvdata(dev, nvdimm_bus->nd_desc);
+
+ return 0;
+}
+
+static struct nd_device_driver nd_bus_driver = {
+ .probe = nd_bus_probe,
+ .remove = nd_bus_remove,
+ .drv = {
+ .name = "nd_bus",
+ .suppress_bind_attrs = true,
+ .bus = &nvdimm_bus_type,
+ .owner = THIS_MODULE,
+ .mod_name = KBUILD_MODNAME,
+ },
+};
+
+static int nvdimm_bus_match(struct device *dev, struct device_driver *drv)
+{
+ struct nd_device_driver *nd_drv = to_nd_device_driver(drv);
+
+ if (is_nvdimm_bus(dev) && nd_drv == &nd_bus_driver)
+ return true;
+
+ return !!test_bit(to_nd_device_type(dev), &nd_drv->type);
+}
+
static ASYNC_DOMAIN_EXCLUSIVE(nd_async_domain);

void nd_synchronize(void)
@@ -864,8 +1030,14 @@ int __init nvdimm_bus_init(void)
goto err_class;
}

+ rc = driver_register(&nd_bus_driver.drv);
+ if (rc)
+ goto err_nd_bus;
+
return 0;

+ err_nd_bus:
+ class_destroy(nd_class);
err_class:
unregister_chrdev(nvdimm_major, "dimmctl");
err_dimm_chrdev:
@@ -878,8 +1050,10 @@ int __init nvdimm_bus_init(void)

void nvdimm_bus_exit(void)
{
+ driver_unregister(&nd_bus_driver.drv);
class_destroy(nd_class);
unregister_chrdev(nvdimm_bus_major, "ndctl");
unregister_chrdev(nvdimm_major, "dimmctl");
bus_unregister(&nvdimm_bus_type);
+ ida_destroy(&nd_ida);
}
diff --git a/drivers/nvdimm/core.c b/drivers/nvdimm/core.c
index e8528756f54f..2c98f958fabb 100644
--- a/drivers/nvdimm/core.c
+++ b/drivers/nvdimm/core.c
@@ -26,7 +26,6 @@

LIST_HEAD(nvdimm_bus_list);
DEFINE_MUTEX(nvdimm_bus_list_mutex);
-static DEFINE_IDA(nd_ida);

void nvdimm_bus_lock(struct device *dev)
{
@@ -195,25 +194,6 @@ u64 nd_fletcher64(void *addr, size_t len, bool le)
}
EXPORT_SYMBOL_GPL(nd_fletcher64);

-static void nvdimm_bus_release(struct device *dev)
-{
- struct nvdimm_bus *nvdimm_bus;
-
- nvdimm_bus = container_of(dev, struct nvdimm_bus, dev);
- ida_simple_remove(&nd_ida, nvdimm_bus->id);
- kfree(nvdimm_bus);
-}
-
-struct nvdimm_bus *to_nvdimm_bus(struct device *dev)
-{
- struct nvdimm_bus *nvdimm_bus;
-
- nvdimm_bus = container_of(dev, struct nvdimm_bus, dev);
- WARN_ON(nvdimm_bus->dev.release != nvdimm_bus_release);
- return nvdimm_bus;
-}
-EXPORT_SYMBOL_GPL(to_nvdimm_bus);
-
struct nvdimm_bus_descriptor *to_nd_desc(struct nvdimm_bus *nvdimm_bus)
{
/* struct nvdimm_bus definition is private to libnvdimm */
@@ -221,19 +201,6 @@ struct nvdimm_bus_descriptor *to_nd_desc(struct nvdimm_bus *nvdimm_bus)
}
EXPORT_SYMBOL_GPL(to_nd_desc);

-struct nvdimm_bus *walk_to_nvdimm_bus(struct device *nd_dev)
-{
- struct device *dev;
-
- for (dev = nd_dev; dev; dev = dev->parent)
- if (dev->release == nvdimm_bus_release)
- break;
- dev_WARN_ONCE(nd_dev, !dev, "invalid dev, not on nd bus\n");
- if (dev)
- return to_nvdimm_bus(dev);
- return NULL;
-}
-
static bool is_uuid_sep(char sep)
{
if (sep == '\n' || sep == '-' || sep == ':' || sep == '\0')
@@ -447,51 +414,6 @@ struct attribute_group nvdimm_bus_attribute_group = {
};
EXPORT_SYMBOL_GPL(nvdimm_bus_attribute_group);

-struct nvdimm_bus *nvdimm_bus_register(struct device *parent,
- struct nvdimm_bus_descriptor *nd_desc)
-{
- struct nvdimm_bus *nvdimm_bus;
- int rc;
-
- nvdimm_bus = kzalloc(sizeof(*nvdimm_bus), GFP_KERNEL);
- if (!nvdimm_bus)
- return NULL;
- INIT_LIST_HEAD(&nvdimm_bus->list);
- INIT_LIST_HEAD(&nvdimm_bus->mapping_list);
- INIT_LIST_HEAD(&nvdimm_bus->poison_list);
- init_waitqueue_head(&nvdimm_bus->probe_wait);
- nvdimm_bus->id = ida_simple_get(&nd_ida, 0, 0, GFP_KERNEL);
- mutex_init(&nvdimm_bus->reconfig_mutex);
- if (nvdimm_bus->id < 0) {
- kfree(nvdimm_bus);
- return NULL;
- }
- nvdimm_bus->nd_desc = nd_desc;
- nvdimm_bus->dev.parent = parent;
- nvdimm_bus->dev.release = nvdimm_bus_release;
- nvdimm_bus->dev.groups = nd_desc->attr_groups;
- dev_set_name(&nvdimm_bus->dev, "ndbus%d", nvdimm_bus->id);
- rc = device_register(&nvdimm_bus->dev);
- if (rc) {
- dev_dbg(&nvdimm_bus->dev, "registration failed: %d\n", rc);
- goto err;
- }
-
- rc = nvdimm_bus_create_ndctl(nvdimm_bus);
- if (rc)
- goto err;
-
- mutex_lock(&nvdimm_bus_list_mutex);
- list_add_tail(&nvdimm_bus->list, &nvdimm_bus_list);
- mutex_unlock(&nvdimm_bus_list_mutex);
-
- return nvdimm_bus;
- err:
- put_device(&nvdimm_bus->dev);
- return NULL;
-}
-EXPORT_SYMBOL_GPL(nvdimm_bus_register);
-
static void set_badblock(struct badblocks *bb, sector_t s, int num)
{
dev_dbg(bb->dev, "Found a poison range (0x%llx, 0x%llx)\n",
@@ -667,54 +589,6 @@ int nvdimm_bus_add_poison(struct nvdimm_bus *nvdimm_bus, u64 addr, u64 length)
}
EXPORT_SYMBOL_GPL(nvdimm_bus_add_poison);

-static void free_poison_list(struct list_head *poison_list)
-{
- struct nd_poison *pl, *next;
-
- list_for_each_entry_safe(pl, next, poison_list, list) {
- list_del(&pl->list);
- kfree(pl);
- }
- list_del_init(poison_list);
-}
-
-static int child_unregister(struct device *dev, void *data)
-{
- /*
- * the singular ndctl class device per bus needs to be
- * "device_destroy"ed, so skip it here
- *
- * i.e. remove classless children
- */
- if (dev->class)
- /* pass */;
- else
- nd_device_unregister(dev, ND_SYNC);
- return 0;
-}
-
-void nvdimm_bus_unregister(struct nvdimm_bus *nvdimm_bus)
-{
- if (!nvdimm_bus)
- return;
-
- mutex_lock(&nvdimm_bus_list_mutex);
- list_del_init(&nvdimm_bus->list);
- mutex_unlock(&nvdimm_bus_list_mutex);
-
- nd_synchronize();
- device_for_each_child(&nvdimm_bus->dev, NULL, child_unregister);
-
- nvdimm_bus_lock(&nvdimm_bus->dev);
- free_poison_list(&nvdimm_bus->poison_list);
- nvdimm_bus_unlock(&nvdimm_bus->dev);
-
- nvdimm_bus_destroy_ndctl(nvdimm_bus);
-
- device_unregister(&nvdimm_bus->dev);
-}
-EXPORT_SYMBOL_GPL(nvdimm_bus_unregister);
-
#ifdef CONFIG_BLK_DEV_INTEGRITY
int nd_integrity_init(struct gendisk *disk, unsigned long meta_size)
{
@@ -773,7 +647,6 @@ static __exit void libnvdimm_exit(void)
nvdimm_bus_exit();
nd_region_devs_exit();
nvdimm_devs_exit();
- ida_destroy(&nd_ida);
}

MODULE_LICENSE("GPL v2");
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