From 7d09e8700226d5e4738da8e9d1afc7ef296310f3 Mon Sep 17 00:00:00 2001 From: Dan Williams Date: Tue, 13 Oct 2020 16:50:13 -0700 Subject: [PATCH] device-dax: introduce 'seed' devices MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit Add a seed device concept for dynamic dax regions to be able to split the region amongst multiple sub-instances. The seed device, similar to libnvdimm seed devices, is a device that starts with zero capacity allocated and unbound to a driver. In contrast to libnvdimm seed devices explicit 'create' and 'delete' interfaces are added to the region to trigger seeds to be created and unused devices to be reclaimed. The explicit create and delete replaces implicit create as a side effect of probe and implicit delete when writing 0 to the size that libnvdimm implements. Delete can be performed on any 0-sized and idle device. This avoids the gymnastics of needing to move device_unregister() to its own async context. Specifically, it avoids the deadlock of deleting a device via one of its own attributes. It is also less surprising to userspace which never sees an extra device it did not request. For now just add the device creation, teardown, and ->probe() prevention. A later patch will arrange for the 'dax/size' attribute to be writable to allocate capacity from the region. Signed-off-by: Dan Williams Signed-off-by: Andrew Morton Cc: Vishal Verma Cc: Brice Goglin Cc: Dave Hansen Cc: Dave Jiang Cc: David Hildenbrand Cc: Ira Weiny Cc: Jia He Cc: Joao Martins Cc: Jonathan Cameron Cc: Andy Lutomirski Cc: Ard Biesheuvel Cc: Ard Biesheuvel Cc: Benjamin Herrenschmidt Cc: Ben Skeggs Cc: Bjorn Helgaas Cc: Borislav Petkov Cc: Boris Ostrovsky Cc: Catalin Marinas Cc: Daniel Vetter Cc: David Airlie Cc: Greg Kroah-Hartman Cc: "H. Peter Anvin" Cc: Hulk Robot Cc: Ingo Molnar Cc: Jason Gunthorpe Cc: Jason Yan Cc: Jeff Moyer Cc: "Jérôme Glisse" Cc: Juergen Gross Cc: kernel test robot Cc: Michael Ellerman Cc: Mike Rapoport Cc: Paul Mackerras Cc: Pavel Tatashin Cc: Peter Zijlstra Cc: "Rafael J. Wysocki" Cc: Randy Dunlap Cc: Stefano Stabellini Cc: Thomas Gleixner Cc: Tom Lendacky Cc: Vivek Goyal Cc: Wei Yang Cc: Will Deacon Link: https://lkml.kernel.org/r/159643101583.4062302.12255093902950754962.stgit@dwillia2-desk3.amr.corp.intel.com Link: https://lkml.kernel.org/r/160106113873.30709.15168756050631539431.stgit@dwillia2-desk3.amr.corp.intel.com Signed-off-by: Linus Torvalds --- drivers/dax/bus.c | 301 +++++++++++++++++++++++++++++++++----- drivers/dax/dax-private.h | 9 ++ drivers/dax/hmem/hmem.c | 2 +- 3 files changed, 272 insertions(+), 40 deletions(-) diff --git a/drivers/dax/bus.c b/drivers/dax/bus.c index 9549f11ebed0c..dce9413a43948 100644 --- a/drivers/dax/bus.c +++ b/drivers/dax/bus.c @@ -139,8 +139,26 @@ static int dax_bus_probe(struct device *dev) { struct dax_device_driver *dax_drv = to_dax_drv(dev->driver); struct dev_dax *dev_dax = to_dev_dax(dev); + struct dax_region *dax_region = dev_dax->region; + struct range *range = &dev_dax->range; + int rc; + + if (range_len(range) == 0 || dev_dax->id < 0) + return -ENXIO; + + rc = dax_drv->probe(dev_dax); + + if (rc || is_static(dax_region)) + return rc; + + /* + * Track new seed creation only after successful probe of the + * previous seed. + */ + if (dax_region->seed == dev) + dax_region->seed = NULL; - return dax_drv->probe(dev_dax); + return 0; } static int dax_bus_remove(struct device *dev) @@ -237,14 +255,216 @@ static ssize_t available_size_show(struct device *dev, } static DEVICE_ATTR_RO(available_size); +static ssize_t seed_show(struct device *dev, + struct device_attribute *attr, char *buf) +{ + struct dax_region *dax_region = dev_get_drvdata(dev); + struct device *seed; + ssize_t rc; + + if (is_static(dax_region)) + return -EINVAL; + + device_lock(dev); + seed = dax_region->seed; + rc = sprintf(buf, "%s\n", seed ? dev_name(seed) : ""); + device_unlock(dev); + + return rc; +} +static DEVICE_ATTR_RO(seed); + +static ssize_t create_show(struct device *dev, + struct device_attribute *attr, char *buf) +{ + struct dax_region *dax_region = dev_get_drvdata(dev); + struct device *youngest; + ssize_t rc; + + if (is_static(dax_region)) + return -EINVAL; + + device_lock(dev); + youngest = dax_region->youngest; + rc = sprintf(buf, "%s\n", youngest ? dev_name(youngest) : ""); + device_unlock(dev); + + return rc; +} + +static ssize_t create_store(struct device *dev, struct device_attribute *attr, + const char *buf, size_t len) +{ + struct dax_region *dax_region = dev_get_drvdata(dev); + unsigned long long avail; + ssize_t rc; + int val; + + if (is_static(dax_region)) + return -EINVAL; + + rc = kstrtoint(buf, 0, &val); + if (rc) + return rc; + if (val != 1) + return -EINVAL; + + device_lock(dev); + avail = dax_region_avail_size(dax_region); + if (avail == 0) + rc = -ENOSPC; + else { + struct dev_dax_data data = { + .dax_region = dax_region, + .size = 0, + .id = -1, + }; + struct dev_dax *dev_dax = devm_create_dev_dax(&data); + + if (IS_ERR(dev_dax)) + rc = PTR_ERR(dev_dax); + else { + /* + * In support of crafting multiple new devices + * simultaneously multiple seeds can be created, + * but only the first one that has not been + * successfully bound is tracked as the region + * seed. + */ + if (!dax_region->seed) + dax_region->seed = &dev_dax->dev; + dax_region->youngest = &dev_dax->dev; + rc = len; + } + } + device_unlock(dev); + + return rc; +} +static DEVICE_ATTR_RW(create); + +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 free_dev_dax_range(struct dev_dax *dev_dax) +{ + struct dax_region *dax_region = dev_dax->region; + struct range *range = &dev_dax->range; + + device_lock_assert(dax_region->dev); + if (range_len(range)) + __release_region(&dax_region->res, range->start, + range_len(range)); +} + +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); + free_dev_dax_range(dev_dax); + device_del(dev); + put_device(dev); +} + +/* a return value >= 0 indicates this invocation invalidated the id */ +static int __free_dev_dax_id(struct dev_dax *dev_dax) +{ + struct dax_region *dax_region = dev_dax->region; + struct device *dev = &dev_dax->dev; + int rc = dev_dax->id; + + device_lock_assert(dev); + + if (is_static(dax_region) || dev_dax->id < 0) + return -1; + ida_free(&dax_region->ida, dev_dax->id); + dev_dax->id = -1; + return rc; +} + +static int free_dev_dax_id(struct dev_dax *dev_dax) +{ + struct device *dev = &dev_dax->dev; + int rc; + + device_lock(dev); + rc = __free_dev_dax_id(dev_dax); + device_unlock(dev); + return rc; +} + +static ssize_t delete_store(struct device *dev, struct device_attribute *attr, + const char *buf, size_t len) +{ + struct dax_region *dax_region = dev_get_drvdata(dev); + struct dev_dax *dev_dax; + struct device *victim; + bool do_del = false; + int rc; + + if (is_static(dax_region)) + return -EINVAL; + + victim = device_find_child_by_name(dax_region->dev, buf); + if (!victim) + return -ENXIO; + + device_lock(dev); + device_lock(victim); + dev_dax = to_dev_dax(victim); + if (victim->driver || range_len(&dev_dax->range)) + rc = -EBUSY; + else { + /* + * Invalidate the device so it does not become active + * again, but always preserve device-id-0 so that + * /sys/bus/dax/ is guaranteed to be populated while any + * dax_region is registered. + */ + if (dev_dax->id > 0) { + do_del = __free_dev_dax_id(dev_dax) >= 0; + rc = len; + if (dax_region->seed == victim) + dax_region->seed = NULL; + if (dax_region->youngest == victim) + dax_region->youngest = NULL; + } else + rc = -EBUSY; + } + device_unlock(victim); + + /* won the race to invalidate the device, clean it up */ + if (do_del) + devm_release_action(dev, unregister_dev_dax, victim); + device_unlock(dev); + put_device(victim); + + return rc; +} +static DEVICE_ATTR_WO(delete); + static umode_t dax_region_visible(struct kobject *kobj, struct attribute *a, int n) { struct device *dev = container_of(kobj, struct device, kobj); struct dax_region *dax_region = dev_get_drvdata(dev); - if (is_static(dax_region) && a == &dev_attr_available_size.attr) - return 0; + if (is_static(dax_region)) + if (a == &dev_attr_available_size.attr + || a == &dev_attr_create.attr + || a == &dev_attr_seed.attr + || a == &dev_attr_delete.attr) + return 0; return a->mode; } @@ -252,6 +472,9 @@ static struct attribute *dax_region_attributes[] = { &dev_attr_available_size.attr, &dev_attr_region_size.attr, &dev_attr_align.attr, + &dev_attr_create.attr, + &dev_attr_seed.attr, + &dev_attr_delete.attr, &dev_attr_id.attr, NULL, }; @@ -320,6 +543,7 @@ struct dax_region *alloc_dax_region(struct device *parent, int region_id, dax_region->align = align; dax_region->dev = parent; dax_region->target_node = target_node; + ida_init(&dax_region->ida); dax_region->res = (struct resource) { .start = res->start, .end = res->end, @@ -347,6 +571,15 @@ static int alloc_dev_dax_range(struct dev_dax *dev_dax, resource_size_t size) device_lock_assert(dax_region->dev); + /* handle the seed alloc special case */ + if (!size) { + dev_dax->range = (struct range) { + .start = res->start, + .end = res->start - 1, + }; + return 0; + } + /* TODO: handle multiple allocations per region */ if (res->child) return -ENOMEM; @@ -448,33 +681,15 @@ static const struct attribute_group *dax_attribute_groups[] = { 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 free_dev_dax_range(struct dev_dax *dev_dax) -{ - struct dax_region *dax_region = dev_dax->region; - struct range *range = &dev_dax->range; - - device_lock_assert(dax_region->dev); - __release_region(&dax_region->res, range->start, range_len(range)); -} - 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); + free_dev_dax_id(dev_dax); + dax_region_put(dax_region); kfree(dev_dax->pgmap); kfree(dev_dax); } @@ -484,18 +699,6 @@ static const struct device_type dev_dax_type = { .groups = dax_attribute_groups, }; -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); - free_dev_dax_range(dev_dax); - device_del(dev); - put_device(dev); -} - struct dev_dax *devm_create_dev_dax(struct dev_dax_data *data) { struct dax_region *dax_region = data->dax_region; @@ -506,17 +709,35 @@ struct dev_dax *devm_create_dev_dax(struct dev_dax_data *data) struct device *dev; int rc; - if (data->id < 0) - return ERR_PTR(-EINVAL); - dev_dax = kzalloc(sizeof(*dev_dax), GFP_KERNEL); if (!dev_dax) return ERR_PTR(-ENOMEM); + if (is_static(dax_region)) { + if (dev_WARN_ONCE(parent, data->id < 0, + "dynamic id specified to static region\n")) { + rc = -EINVAL; + goto err_id; + } + + dev_dax->id = data->id; + } else { + if (dev_WARN_ONCE(parent, data->id >= 0, + "static id specified to dynamic region\n")) { + rc = -EINVAL; + goto err_id; + } + + rc = ida_alloc(&dax_region->ida, GFP_KERNEL); + if (rc < 0) + goto err_id; + dev_dax->id = rc; + } + dev_dax->region = dax_region; dev = &dev_dax->dev; device_initialize(dev); - dev_set_name(dev, "dax%d.%d", dax_region->id, data->id); + dev_set_name(dev, "dax%d.%d", dax_region->id, dev_dax->id); rc = alloc_dev_dax_range(dev_dax, data->size); if (rc) @@ -579,6 +800,8 @@ err_alloc_dax: err_pgmap: free_dev_dax_range(dev_dax); err_range: + free_dev_dax_id(dev_dax); +err_id: kfree(dev_dax); return ERR_PTR(rc); diff --git a/drivers/dax/dax-private.h b/drivers/dax/dax-private.h index 99b1273bb2320..b81a1494d82bb 100644 --- a/drivers/dax/dax-private.h +++ b/drivers/dax/dax-private.h @@ -7,6 +7,7 @@ #include #include +#include /* private routines between core files */ struct dax_device; @@ -22,7 +23,10 @@ void dax_bus_exit(void); * @kref: to pin while other agents have a need to do lookups * @dev: parent device backing this region * @align: allocation and mapping alignment for child dax devices + * @ida: instance id allocator * @res: resource tree to track instance allocations + * @seed: allow userspace to find the first unbound seed device + * @youngest: allow userspace to find the most recently created device */ struct dax_region { int id; @@ -30,7 +34,10 @@ struct dax_region { struct kref kref; struct device *dev; unsigned int align; + struct ida ida; struct resource res; + struct device *seed; + struct device *youngest; }; /** @@ -39,6 +46,7 @@ struct dax_region { * @region - parent region * @dax_dev - core dax functionality * @target_node: effective numa node if dev_dax memory range is onlined + * @id: ida allocated id * @dev - device core * @pgmap - pgmap for memmap setup / lifetime (driver owned) * @range: resource range for the instance @@ -47,6 +55,7 @@ struct dev_dax { struct dax_region *region; struct dax_device *dax_dev; int target_node; + int id; struct device dev; struct dev_pagemap *pgmap; struct range range; diff --git a/drivers/dax/hmem/hmem.c b/drivers/dax/hmem/hmem.c index e7b64539e23e8..aa260009dfc79 100644 --- a/drivers/dax/hmem/hmem.c +++ b/drivers/dax/hmem/hmem.c @@ -26,7 +26,7 @@ static int dax_hmem_probe(struct platform_device *pdev) data = (struct dev_dax_data) { .dax_region = dax_region, - .id = 0, + .id = -1, .size = resource_size(res), }; dev_dax = devm_create_dev_dax(&data); -- 2.39.5