Re: [PATCH v5 01/17] device-dax: make pgmap optional for instance creation

[David Hildenbrand <david@redhat.com>]

On 25.09.20 21:11, Dan Williams wrote:
> The passed in dev_pagemap is only required in the pmem case as the
> libnvdimm core may have reserved a vmem_altmap for dev_memremap_pages() to
> place the memmap in pmem directly.  In the hmem case there is no agent
> reserving an altmap so it can all be handled by a core internal default.
> 
> Pass the resource range via a new @range property of 'struct
> dev_dax_data'.
> 
> Link: https://lkml.kernel.org/r/159643099958.4062302.10379230791041872886.stgit@dwillia2-desk3.amr.corp.intel.com
> Cc: David Hildenbrand <david@redhat.com>
> Cc: Vishal Verma <vishal.l.verma@intel.com>
> Cc: Dave Hansen <dave.hansen@linux.intel.com>
> Cc: Pavel Tatashin <pasha.tatashin@soleen.com>
> Cc: Brice Goglin <Brice.Goglin@inria.fr>
> Cc: Dave Jiang <dave.jiang@intel.com>
> Cc: David Hildenbrand <david@redhat.com>
> Cc: Ira Weiny <ira.weiny@intel.com>
> Cc: Jia He <justin.he@arm.com>
> Cc: Joao Martins <joao.m.martins@oracle.com>
> Cc: Jonathan Cameron <Jonathan.Cameron@huawei.com>
> Signed-off-by: Dan Williams <dan.j.williams@intel.com>
> ---
>  drivers/dax/bus.c              |   29 +++++++++++++++--------------
>  drivers/dax/bus.h              |    2 ++
>  drivers/dax/dax-private.h      |    9 ++++++++-
>  drivers/dax/device.c           |   28 +++++++++++++++++++---------
>  drivers/dax/hmem/hmem.c        |    8 ++++----
>  drivers/dax/kmem.c             |   12 ++++++------
>  drivers/dax/pmem/core.c        |    4 ++++
>  tools/testing/nvdimm/dax-dev.c |    8 ++++----
>  8 files changed, 62 insertions(+), 38 deletions(-)
> 
> diff --git a/drivers/dax/bus.c b/drivers/dax/bus.c
> index dffa4655e128..96bd64ba95a5 100644
> --- a/drivers/dax/bus.c
> +++ b/drivers/dax/bus.c
> @@ -271,7 +271,7 @@ 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);
> +	unsigned long long size = range_len(&dev_dax->range);
>  
>  	return sprintf(buf, "%llu\n", size);
>  }
> @@ -293,19 +293,12 @@ static ssize_t target_node_show(struct device *dev,
>  }
>  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));
> +	return sprintf(buf, "%#llx\n", dev_dax->range.start);
>  }
>  static DEVICE_ATTR(resource, 0400, resource_show, NULL);
>  
> @@ -376,6 +369,7 @@ static void dev_dax_release(struct device *dev)
>  
>  	dax_region_put(dax_region);
>  	put_dax(dax_dev);
> +	kfree(dev_dax->pgmap);
>  	kfree(dev_dax);
>  }
>  
> @@ -412,7 +406,12 @@ struct dev_dax *devm_create_dev_dax(struct dev_dax_data *data)
>  	if (!dev_dax)
>  		return ERR_PTR(-ENOMEM);
>  
> -	memcpy(&dev_dax->pgmap, data->pgmap, sizeof(struct dev_pagemap));
> +	if (data->pgmap) {
> +		dev_dax->pgmap = kmemdup(data->pgmap,
> +				sizeof(struct dev_pagemap), GFP_KERNEL);
> +		if (!dev_dax->pgmap)
> +			goto err_pgmap;
> +	}
>  
>  	/*
>  	 * No 'host' or dax_operations since there is no access to this
> @@ -421,18 +420,19 @@ struct dev_dax *devm_create_dev_dax(struct dev_dax_data *data)
>  	dax_dev = alloc_dax(dev_dax, NULL, NULL, DAXDEV_F_SYNC);
>  	if (IS_ERR(dax_dev)) {
>  		rc = PTR_ERR(dax_dev);
> -		goto err;
> +		goto err_alloc_dax;
>  	}
>  
>  	/* 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() */
> +	/* from here on we're committed to teardown via dev_dax_release() */
>  	dev = &dev_dax->dev;
>  	device_initialize(dev);
>  
>  	dev_dax->dax_dev = dax_dev;
>  	dev_dax->region = dax_region;
> +	dev_dax->range = data->range;
>  	dev_dax->target_node = dax_region->target_node;
>  	kref_get(&dax_region->kref);
>  
> @@ -458,8 +458,9 @@ struct dev_dax *devm_create_dev_dax(struct dev_dax_data *data)
>  		return ERR_PTR(rc);
>  
>  	return dev_dax;
> -
> - err:
> +err_alloc_dax:
> +	kfree(dev_dax->pgmap);
> +err_pgmap:
>  	kfree(dev_dax);
>  
>  	return ERR_PTR(rc);
> diff --git a/drivers/dax/bus.h b/drivers/dax/bus.h
> index 299c2e7fac09..4aeb36da83a4 100644
> --- a/drivers/dax/bus.h
> +++ b/drivers/dax/bus.h
> @@ -3,6 +3,7 @@
>  #ifndef __DAX_BUS_H__
>  #define __DAX_BUS_H__
>  #include <linux/device.h>
> +#include <linux/range.h>
>  
>  struct dev_dax;
>  struct resource;
> @@ -21,6 +22,7 @@ struct dev_dax_data {
>  	struct dax_region *dax_region;
>  	struct dev_pagemap *pgmap;
>  	enum dev_dax_subsys subsys;
> +	struct range range;
>  	int id;
>  };
>  
> diff --git a/drivers/dax/dax-private.h b/drivers/dax/dax-private.h
> index 8a4c40ccd2ef..6779f683671d 100644
> --- a/drivers/dax/dax-private.h
> +++ b/drivers/dax/dax-private.h
> @@ -41,6 +41,7 @@ struct dax_region {
>   * @target_node: effective numa node if dev_dax memory range is onlined
>   * @dev - device core
>   * @pgmap - pgmap for memmap setup / lifetime (driver owned)
> + * @range: resource range for the instance
>   * @dax_mem_res: physical address range of hotadded DAX memory
>   * @dax_mem_name: name for hotadded DAX memory via add_memory_driver_managed()
>   */
> @@ -49,10 +50,16 @@ struct dev_dax {
>  	struct dax_device *dax_dev;
>  	int target_node;
>  	struct device dev;
> -	struct dev_pagemap pgmap;
> +	struct dev_pagemap *pgmap;
> +	struct range range;
>  	struct resource *dax_kmem_res;
>  };
>  
> +static inline u64 range_len(struct range *range)
> +{
> +	return range->end - range->start + 1;
> +}

include/linux/range.h seems to have this function - why is this here needed?

-- 
Thanks,

David / dhildenb