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authorDan Williams <dan.j.williams@intel.com>2018-11-07 15:31:23 -0800
committerDan Williams <dan.j.williams@intel.com>2019-01-06 21:41:55 -0800
commitd200781ef237a354d918ceff5cee350d88a93d42 (patch)
treeafd53c6e25a57e31b8c0c8542e086bd50840bc9a /drivers/dax/bus.c
parent89ec9f2cfa36cc5fca2fb445ed221bb9add7b536 (diff)
downloadlinux-d200781ef237a354d918ceff5cee350d88a93d42.tar.bz2
device-dax: Add support for a dax override driver
Introduce the 'new_id' concept for enabling a custom device-driver attach policy for dax-bus drivers. The intended use is to have a mechanism for hot-plugging device-dax ranges into the page allocator on-demand. With this in place the default policy of using device-dax for performance differentiated memory can be overridden by user-space policy that can arrange for the memory range to be managed as 'System RAM' with user-defined NUMA and other performance attributes. Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Diffstat (limited to 'drivers/dax/bus.c')
-rw-r--r--drivers/dax/bus.c145
1 files changed, 140 insertions, 5 deletions
diff --git a/drivers/dax/bus.c b/drivers/dax/bus.c
index 69aae2cbd45f..17af6fbc3be5 100644
--- a/drivers/dax/bus.c
+++ b/drivers/dax/bus.c
@@ -2,11 +2,21 @@
/* 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 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)
{
/*
@@ -16,22 +26,115 @@ static int dax_bus_uevent(struct device *dev, struct kobj_uevent_env *env)
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;
+}
+
+static ssize_t do_id_store(struct device_driver *drv, const char *buf,
+ size_t count, bool add)
+{
+ 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 (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 (!add) {
+ list_del(&dax_id->list);
+ kfree(dax_id);
+ } else
+ /* dax_id already added */;
+ mutex_unlock(&dax_bus_lock);
+ return rc;
+}
+
+static ssize_t new_id_store(struct device_driver *drv, const char *buf,
+ size_t count)
+{
+ return do_id_store(drv, buf, count, true);
+}
+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, false);
+}
+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);
+
/*
- * The drivers that can register on the 'dax' bus are private to
- * drivers/dax/ so any device and driver on the bus always
- * match.
+ * All but the 'device-dax' driver, which has 'match_always'
+ * set, requires an exact id match.
*/
- return 1;
+ if (dax_drv->match_always)
+ return 1;
+
+ return dax_match_id(dax_drv, dev);
}
/*
@@ -273,17 +376,49 @@ struct dev_dax *devm_create_dev_dax(struct dax_region *dax_region, int id,
}
EXPORT_SYMBOL_GPL(devm_create_dev_dax);
-int __dax_driver_register(struct device_driver *drv,
+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 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);
+}
+EXPORT_SYMBOL_GPL(dax_driver_unregister);
+
int __init dax_bus_init(void)
{
return bus_register(&dax_bus_type);