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SubjectRe: [PATCH v5 04/17] device-dax/kmem: replace release_resource() with release_mem_region()
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On 25.09.20 21:12, Dan Williams wrote:
> Towards removing the mode specific @dax_kmem_res attribute from the
> generic 'struct dev_dax', and preparing for multi-range support, change
> the kmem driver to use the idiomatic release_mem_region() to pair with
> the initial request_mem_region(). This also eliminates the need to open
> code the release of the resource allocated by request_mem_region().
>
> As there are no more dax_kmem_res users, delete this struct member.
>
> 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/dax-private.h | 3 ---
> drivers/dax/kmem.c | 20 +++++++-------------
> 2 files changed, 7 insertions(+), 16 deletions(-)
>
> diff --git a/drivers/dax/dax-private.h b/drivers/dax/dax-private.h
> index 6779f683671d..12a2dbc43b40 100644
> --- a/drivers/dax/dax-private.h
> +++ b/drivers/dax/dax-private.h
> @@ -42,8 +42,6 @@ struct dax_region {
> * @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()
> */
> struct dev_dax {
> struct dax_region *region;
> @@ -52,7 +50,6 @@ struct dev_dax {
> struct device dev;
> struct dev_pagemap *pgmap;
> struct range range;
> - struct resource *dax_kmem_res;
> };
>
> static inline u64 range_len(struct range *range)
> diff --git a/drivers/dax/kmem.c b/drivers/dax/kmem.c
> index 6fe2cb1c5f7c..e56fc688bdc5 100644
> --- a/drivers/dax/kmem.c
> +++ b/drivers/dax/kmem.c
> @@ -33,7 +33,7 @@ int dev_dax_kmem_probe(struct device *dev)
> {
> struct dev_dax *dev_dax = to_dev_dax(dev);
> struct range range = dax_kmem_range(dev_dax);
> - struct resource *new_res;
> + struct resource *res;
> char *res_name;
> int numa_node;
> int rc;
> @@ -56,8 +56,8 @@ int dev_dax_kmem_probe(struct device *dev)
> return -ENOMEM;
>
> /* Region is permanently reserved if hotremove fails. */
> - new_res = request_mem_region(range.start, range_len(&range), res_name);
> - if (!new_res) {
> + res = request_mem_region(range.start, range_len(&range), res_name);
> + if (!res) {
> dev_warn(dev, "could not reserve region [%#llx-%#llx]\n", range.start, range.end);
> kfree(res_name);
> return -EBUSY;
> @@ -69,23 +69,20 @@ int dev_dax_kmem_probe(struct device *dev)
> * inherit flags from the parent since it may set new flags
> * unknown to us that will break add_memory() below.
> */
> - new_res->flags = IORESOURCE_SYSTEM_RAM;
> + res->flags = IORESOURCE_SYSTEM_RAM;
>
> /*
> * Ensure that future kexec'd kernels will not treat this as RAM
> * automatically.
> */
> - rc = add_memory_driver_managed(numa_node, new_res->start,
> - resource_size(new_res), kmem_name);
> + rc = add_memory_driver_managed(numa_node, range.start, range_len(&range), kmem_name);
> if (rc) {
> - release_resource(new_res);
> - kfree(new_res);
> + release_mem_region(range.start, range_len(&range));
> kfree(res_name);
> return rc;
> }
>
> dev_set_drvdata(dev, res_name);
> - dev_dax->dax_kmem_res = new_res;
>
> return 0;
> }
> @@ -95,7 +92,6 @@ static int dev_dax_kmem_remove(struct device *dev)
> {
> struct dev_dax *dev_dax = to_dev_dax(dev);
> struct range range = dax_kmem_range(dev_dax);
> - struct resource *res = dev_dax->dax_kmem_res;
> const char *res_name = dev_get_drvdata(dev);
> int rc;
>
> @@ -114,10 +110,8 @@ static int dev_dax_kmem_remove(struct device *dev)
> }
>
> /* Release and free dax resources */
> - release_resource(res);
> - kfree(res);
> + release_mem_region(range.start, range_len(&range));

Does that work? AFAIKs,

__release_region(&iomem_resource, (start), (n)) -> __release_region()

will only remove stuff that is IORESOURCE_BUSY.

Maybe storing it in drvdata is indeed the easiest way to remove it from
struct dax_region.

--
Thanks,

David / dhildenb

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