linux/drivers/dax/bus.c
Linus Torvalds 0fe49f70a0 - Fix a hang condition that started triggering after the Xarray
conversion of fsdax in the v4.20 kernel.
 
 - Add a 'resource' (root-only physical base address) sysfs attribute to
   device-dax instances to correlate memory-blocks onlined via the kmem
   driver with a given device instance.
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Merge tag 'dax-for-5.3' of git://git.kernel.org/pub/scm/linux/kernel/git/nvdimm/nvdimm

Pull dax updates from Dan Williams:
 "The fruits of a bug hunt in the fsdax implementation with Willy and a
  small feature update for device-dax:

   - Fix a hang condition that started triggering after the Xarray
     conversion of fsdax in the v4.20 kernel.

   - Add a 'resource' (root-only physical base address) sysfs attribute
     to device-dax instances to correlate memory-blocks onlined via the
     kmem driver with a given device instance"

* tag 'dax-for-5.3' of git://git.kernel.org/pub/scm/linux/kernel/git/nvdimm/nvdimm:
  dax: Fix missed wakeup with PMD faults
  device-dax: Add a 'resource' attribute
2019-07-18 10:58:52 -07:00

523 lines
12 KiB
C

// SPDX-License-Identifier: GPL-2.0
/* Copyright(c) 2017-2018 Intel Corporation. All rights reserved. */
#include <linux/memremap.h>
#include <linux/device.h>
#include <linux/mutex.h>
#include <linux/list.h>
#include <linux/slab.h>
#include <linux/dax.h>
#include "dax-private.h"
#include "bus.h"
static struct class *dax_class;
static DEFINE_MUTEX(dax_bus_lock);
#define DAX_NAME_LEN 30
struct dax_id {
struct list_head list;
char dev_name[DAX_NAME_LEN];
};
static int dax_bus_uevent(struct device *dev, struct kobj_uevent_env *env)
{
/*
* We only ever expect to handle device-dax instances, i.e. the
* @type argument to MODULE_ALIAS_DAX_DEVICE() is always zero
*/
return add_uevent_var(env, "MODALIAS=" DAX_DEVICE_MODALIAS_FMT, 0);
}
static struct dax_device_driver *to_dax_drv(struct device_driver *drv)
{
return container_of(drv, struct dax_device_driver, drv);
}
static struct dax_id *__dax_match_id(struct dax_device_driver *dax_drv,
const char *dev_name)
{
struct dax_id *dax_id;
lockdep_assert_held(&dax_bus_lock);
list_for_each_entry(dax_id, &dax_drv->ids, list)
if (sysfs_streq(dax_id->dev_name, dev_name))
return dax_id;
return NULL;
}
static int dax_match_id(struct dax_device_driver *dax_drv, struct device *dev)
{
int match;
mutex_lock(&dax_bus_lock);
match = !!__dax_match_id(dax_drv, dev_name(dev));
mutex_unlock(&dax_bus_lock);
return match;
}
enum id_action {
ID_REMOVE,
ID_ADD,
};
static ssize_t do_id_store(struct device_driver *drv, const char *buf,
size_t count, enum id_action action)
{
struct dax_device_driver *dax_drv = to_dax_drv(drv);
unsigned int region_id, id;
char devname[DAX_NAME_LEN];
struct dax_id *dax_id;
ssize_t rc = count;
int fields;
fields = sscanf(buf, "dax%d.%d", &region_id, &id);
if (fields != 2)
return -EINVAL;
sprintf(devname, "dax%d.%d", region_id, id);
if (!sysfs_streq(buf, devname))
return -EINVAL;
mutex_lock(&dax_bus_lock);
dax_id = __dax_match_id(dax_drv, buf);
if (!dax_id) {
if (action == ID_ADD) {
dax_id = kzalloc(sizeof(*dax_id), GFP_KERNEL);
if (dax_id) {
strncpy(dax_id->dev_name, buf, DAX_NAME_LEN);
list_add(&dax_id->list, &dax_drv->ids);
} else
rc = -ENOMEM;
} else
/* nothing to remove */;
} else if (action == ID_REMOVE) {
list_del(&dax_id->list);
kfree(dax_id);
} else
/* dax_id already added */;
mutex_unlock(&dax_bus_lock);
if (rc < 0)
return rc;
if (action == ID_ADD)
rc = driver_attach(drv);
if (rc)
return rc;
return count;
}
static ssize_t new_id_store(struct device_driver *drv, const char *buf,
size_t count)
{
return do_id_store(drv, buf, count, ID_ADD);
}
static DRIVER_ATTR_WO(new_id);
static ssize_t remove_id_store(struct device_driver *drv, const char *buf,
size_t count)
{
return do_id_store(drv, buf, count, ID_REMOVE);
}
static DRIVER_ATTR_WO(remove_id);
static struct attribute *dax_drv_attrs[] = {
&driver_attr_new_id.attr,
&driver_attr_remove_id.attr,
NULL,
};
ATTRIBUTE_GROUPS(dax_drv);
static int dax_bus_match(struct device *dev, struct device_driver *drv);
static struct bus_type dax_bus_type = {
.name = "dax",
.uevent = dax_bus_uevent,
.match = dax_bus_match,
.drv_groups = dax_drv_groups,
};
static int dax_bus_match(struct device *dev, struct device_driver *drv)
{
struct dax_device_driver *dax_drv = to_dax_drv(drv);
/*
* All but the 'device-dax' driver, which has 'match_always'
* set, requires an exact id match.
*/
if (dax_drv->match_always)
return 1;
return dax_match_id(dax_drv, dev);
}
/*
* Rely on the fact that drvdata is set before the attributes are
* registered, and that the attributes are unregistered before drvdata
* is cleared to assume that drvdata is always valid.
*/
static ssize_t id_show(struct device *dev,
struct device_attribute *attr, char *buf)
{
struct dax_region *dax_region = dev_get_drvdata(dev);
return sprintf(buf, "%d\n", dax_region->id);
}
static DEVICE_ATTR_RO(id);
static ssize_t region_size_show(struct device *dev,
struct device_attribute *attr, char *buf)
{
struct dax_region *dax_region = dev_get_drvdata(dev);
return sprintf(buf, "%llu\n", (unsigned long long)
resource_size(&dax_region->res));
}
static struct device_attribute dev_attr_region_size = __ATTR(size, 0444,
region_size_show, NULL);
static ssize_t align_show(struct device *dev,
struct device_attribute *attr, char *buf)
{
struct dax_region *dax_region = dev_get_drvdata(dev);
return sprintf(buf, "%u\n", dax_region->align);
}
static DEVICE_ATTR_RO(align);
static struct attribute *dax_region_attributes[] = {
&dev_attr_region_size.attr,
&dev_attr_align.attr,
&dev_attr_id.attr,
NULL,
};
static const struct attribute_group dax_region_attribute_group = {
.name = "dax_region",
.attrs = dax_region_attributes,
};
static const struct attribute_group *dax_region_attribute_groups[] = {
&dax_region_attribute_group,
NULL,
};
static void dax_region_free(struct kref *kref)
{
struct dax_region *dax_region;
dax_region = container_of(kref, struct dax_region, kref);
kfree(dax_region);
}
void dax_region_put(struct dax_region *dax_region)
{
kref_put(&dax_region->kref, dax_region_free);
}
EXPORT_SYMBOL_GPL(dax_region_put);
static void dax_region_unregister(void *region)
{
struct dax_region *dax_region = region;
sysfs_remove_groups(&dax_region->dev->kobj,
dax_region_attribute_groups);
dax_region_put(dax_region);
}
struct dax_region *alloc_dax_region(struct device *parent, int region_id,
struct resource *res, int target_node, unsigned int align,
unsigned long pfn_flags)
{
struct dax_region *dax_region;
/*
* The DAX core assumes that it can store its private data in
* parent->driver_data. This WARN is a reminder / safeguard for
* developers of device-dax drivers.
*/
if (dev_get_drvdata(parent)) {
dev_WARN(parent, "dax core failed to setup private data\n");
return NULL;
}
if (!IS_ALIGNED(res->start, align)
|| !IS_ALIGNED(resource_size(res), align))
return NULL;
dax_region = kzalloc(sizeof(*dax_region), GFP_KERNEL);
if (!dax_region)
return NULL;
dev_set_drvdata(parent, dax_region);
memcpy(&dax_region->res, res, sizeof(*res));
dax_region->pfn_flags = pfn_flags;
kref_init(&dax_region->kref);
dax_region->id = region_id;
dax_region->align = align;
dax_region->dev = parent;
dax_region->target_node = target_node;
if (sysfs_create_groups(&parent->kobj, dax_region_attribute_groups)) {
kfree(dax_region);
return NULL;
}
kref_get(&dax_region->kref);
if (devm_add_action_or_reset(parent, dax_region_unregister, dax_region))
return NULL;
return dax_region;
}
EXPORT_SYMBOL_GPL(alloc_dax_region);
static ssize_t size_show(struct device *dev,
struct device_attribute *attr, char *buf)
{
struct dev_dax *dev_dax = to_dev_dax(dev);
unsigned long long size = resource_size(&dev_dax->region->res);
return sprintf(buf, "%llu\n", size);
}
static DEVICE_ATTR_RO(size);
static int dev_dax_target_node(struct dev_dax *dev_dax)
{
struct dax_region *dax_region = dev_dax->region;
return dax_region->target_node;
}
static ssize_t target_node_show(struct device *dev,
struct device_attribute *attr, char *buf)
{
struct dev_dax *dev_dax = to_dev_dax(dev);
return sprintf(buf, "%d\n", dev_dax_target_node(dev_dax));
}
static DEVICE_ATTR_RO(target_node);
static unsigned long long dev_dax_resource(struct dev_dax *dev_dax)
{
struct dax_region *dax_region = dev_dax->region;
return dax_region->res.start;
}
static ssize_t resource_show(struct device *dev,
struct device_attribute *attr, char *buf)
{
struct dev_dax *dev_dax = to_dev_dax(dev);
return sprintf(buf, "%#llx\n", dev_dax_resource(dev_dax));
}
static DEVICE_ATTR_RO(resource);
static ssize_t modalias_show(struct device *dev, struct device_attribute *attr,
char *buf)
{
/*
* We only ever expect to handle device-dax instances, i.e. the
* @type argument to MODULE_ALIAS_DAX_DEVICE() is always zero
*/
return sprintf(buf, DAX_DEVICE_MODALIAS_FMT "\n", 0);
}
static DEVICE_ATTR_RO(modalias);
static umode_t dev_dax_visible(struct kobject *kobj, struct attribute *a, int n)
{
struct device *dev = container_of(kobj, struct device, kobj);
struct dev_dax *dev_dax = to_dev_dax(dev);
if (a == &dev_attr_target_node.attr && dev_dax_target_node(dev_dax) < 0)
return 0;
if (a == &dev_attr_resource.attr)
return 0400;
return a->mode;
}
static struct attribute *dev_dax_attributes[] = {
&dev_attr_modalias.attr,
&dev_attr_size.attr,
&dev_attr_target_node.attr,
&dev_attr_resource.attr,
NULL,
};
static const struct attribute_group dev_dax_attribute_group = {
.attrs = dev_dax_attributes,
.is_visible = dev_dax_visible,
};
static const struct attribute_group *dax_attribute_groups[] = {
&dev_dax_attribute_group,
NULL,
};
void kill_dev_dax(struct dev_dax *dev_dax)
{
struct dax_device *dax_dev = dev_dax->dax_dev;
struct inode *inode = dax_inode(dax_dev);
kill_dax(dax_dev);
unmap_mapping_range(inode->i_mapping, 0, 0, 1);
}
EXPORT_SYMBOL_GPL(kill_dev_dax);
static void dev_dax_release(struct device *dev)
{
struct dev_dax *dev_dax = to_dev_dax(dev);
struct dax_region *dax_region = dev_dax->region;
struct dax_device *dax_dev = dev_dax->dax_dev;
dax_region_put(dax_region);
put_dax(dax_dev);
kfree(dev_dax);
}
static void unregister_dev_dax(void *dev)
{
struct dev_dax *dev_dax = to_dev_dax(dev);
dev_dbg(dev, "%s\n", __func__);
kill_dev_dax(dev_dax);
device_del(dev);
put_device(dev);
}
struct dev_dax *__devm_create_dev_dax(struct dax_region *dax_region, int id,
struct dev_pagemap *pgmap, enum dev_dax_subsys subsys)
{
struct device *parent = dax_region->dev;
struct dax_device *dax_dev;
struct dev_dax *dev_dax;
struct inode *inode;
struct device *dev;
int rc = -ENOMEM;
if (id < 0)
return ERR_PTR(-EINVAL);
dev_dax = kzalloc(sizeof(*dev_dax), GFP_KERNEL);
if (!dev_dax)
return ERR_PTR(-ENOMEM);
memcpy(&dev_dax->pgmap, pgmap, sizeof(*pgmap));
/*
* No 'host' or dax_operations since there is no access to this
* device outside of mmap of the resulting character device.
*/
dax_dev = alloc_dax(dev_dax, NULL, NULL, DAXDEV_F_SYNC);
if (!dax_dev)
goto err;
/* a device_dax instance is dead while the driver is not attached */
kill_dax(dax_dev);
/* from here on we're committed to teardown via dax_dev_release() */
dev = &dev_dax->dev;
device_initialize(dev);
dev_dax->dax_dev = dax_dev;
dev_dax->region = dax_region;
dev_dax->target_node = dax_region->target_node;
kref_get(&dax_region->kref);
inode = dax_inode(dax_dev);
dev->devt = inode->i_rdev;
if (subsys == DEV_DAX_BUS)
dev->bus = &dax_bus_type;
else
dev->class = dax_class;
dev->parent = parent;
dev->groups = dax_attribute_groups;
dev->release = dev_dax_release;
dev_set_name(dev, "dax%d.%d", dax_region->id, id);
rc = device_add(dev);
if (rc) {
kill_dev_dax(dev_dax);
put_device(dev);
return ERR_PTR(rc);
}
rc = devm_add_action_or_reset(dax_region->dev, unregister_dev_dax, dev);
if (rc)
return ERR_PTR(rc);
return dev_dax;
err:
kfree(dev_dax);
return ERR_PTR(rc);
}
EXPORT_SYMBOL_GPL(__devm_create_dev_dax);
static int match_always_count;
int __dax_driver_register(struct dax_device_driver *dax_drv,
struct module *module, const char *mod_name)
{
struct device_driver *drv = &dax_drv->drv;
int rc = 0;
INIT_LIST_HEAD(&dax_drv->ids);
drv->owner = module;
drv->name = mod_name;
drv->mod_name = mod_name;
drv->bus = &dax_bus_type;
/* there can only be one default driver */
mutex_lock(&dax_bus_lock);
match_always_count += dax_drv->match_always;
if (match_always_count > 1) {
match_always_count--;
WARN_ON(1);
rc = -EINVAL;
}
mutex_unlock(&dax_bus_lock);
if (rc)
return rc;
return driver_register(drv);
}
EXPORT_SYMBOL_GPL(__dax_driver_register);
void dax_driver_unregister(struct dax_device_driver *dax_drv)
{
struct device_driver *drv = &dax_drv->drv;
struct dax_id *dax_id, *_id;
mutex_lock(&dax_bus_lock);
match_always_count -= dax_drv->match_always;
list_for_each_entry_safe(dax_id, _id, &dax_drv->ids, list) {
list_del(&dax_id->list);
kfree(dax_id);
}
mutex_unlock(&dax_bus_lock);
driver_unregister(drv);
}
EXPORT_SYMBOL_GPL(dax_driver_unregister);
int __init dax_bus_init(void)
{
int rc;
if (IS_ENABLED(CONFIG_DEV_DAX_PMEM_COMPAT)) {
dax_class = class_create(THIS_MODULE, "dax");
if (IS_ERR(dax_class))
return PTR_ERR(dax_class);
}
rc = bus_register(&dax_bus_type);
if (rc)
class_destroy(dax_class);
return rc;
}
void __exit dax_bus_exit(void)
{
bus_unregister(&dax_bus_type);
class_destroy(dax_class);
}