Re: [PATCH 4/4] dax: Cleanup extra dax_region references

[Dave Jiang]

On 6/2/23 23:14, Dan Williams wrote:

Now that free_dev_dax_id() internally manages the references it needs
the extra references taken by the dax_region drivers are not needed.

Reported-by: Ira Weiny <ira.we...@intel.com>
Signed-off-by: Dan Williams <dan.j.willi...@intel.com>

Reviewed-by: Dave Jiang <dave.ji...@intel.com>

---
  drivers/dax/bus.c       |    4 +---
  drivers/dax/bus.h       |    1 -
  drivers/dax/cxl.c       |    8 +-------
  drivers/dax/hmem/hmem.c |    8 +-------
  drivers/dax/pmem.c      |    7 +------
  5 files changed, 4 insertions(+), 24 deletions(-)

diff --git a/drivers/dax/bus.c b/drivers/dax/bus.c
index a4cc3eca774f..0ee96e6fc426 100644
--- a/drivers/dax/bus.c
+++ b/drivers/dax/bus.c
@@ -454,11 +454,10 @@ static void dax_region_free(struct kref *kref)
        kfree(dax_region);
  }

-void dax_region_put(struct dax_region *dax_region)

+static void dax_region_put(struct dax_region *dax_region)
  {
        kref_put(&dax_region->kref, dax_region_free);
  }
-EXPORT_SYMBOL_GPL(dax_region_put);

/* a return value >= 0 indicates this invocation invalidated the id */

  static int __free_dev_dax_id(struct dev_dax *dev_dax)
@@ -641,7 +640,6 @@ struct dax_region *alloc_dax_region(struct device *parent, 
int region_id,
                return NULL;
        }

- kref_get(&dax_region->kref);

        if (devm_add_action_or_reset(parent, dax_region_unregister, dax_region))
                return NULL;
        return dax_region;
diff --git a/drivers/dax/bus.h b/drivers/dax/bus.h
index 8cd79ab34292..bdbf719df5c5 100644
--- a/drivers/dax/bus.h
+++ b/drivers/dax/bus.h
@@ -9,7 +9,6 @@ struct dev_dax;
  struct resource;
  struct dax_device;
  struct dax_region;
-void dax_region_put(struct dax_region *dax_region);

/* dax bus specific ioresource flags */

  #define IORESOURCE_DAX_STATIC BIT(0)
diff --git a/drivers/dax/cxl.c b/drivers/dax/cxl.c
index ccdf8de85bd5..8bc9d04034d6 100644
--- a/drivers/dax/cxl.c
+++ b/drivers/dax/cxl.c
@@ -13,7 +13,6 @@ static int cxl_dax_region_probe(struct device *dev)
        struct cxl_region *cxlr = cxlr_dax->cxlr;
        struct dax_region *dax_region;
        struct dev_dax_data data;
-       struct dev_dax *dev_dax;

if (nid == NUMA_NO_NODE)

                nid = memory_add_physaddr_to_nid(cxlr_dax->hpa_range.start);
@@ -28,13 +27,8 @@ static int cxl_dax_region_probe(struct device *dev)
                .id = -1,
                .size = range_len(&cxlr_dax->hpa_range),
        };
-       dev_dax = devm_create_dev_dax(&data);
-       if (IS_ERR(dev_dax))
-               return PTR_ERR(dev_dax);

- /* child dev_dax instances now own the lifetime of the dax_region */

-       dax_region_put(dax_region);
-       return 0;
+       return PTR_ERR_OR_ZERO(devm_create_dev_dax(&data));
  }

static struct cxl_driver cxl_dax_region_driver = {

diff --git a/drivers/dax/hmem/hmem.c b/drivers/dax/hmem/hmem.c
index e5fe8b39fb94..5d2ddef0f8f5 100644
--- a/drivers/dax/hmem/hmem.c
+++ b/drivers/dax/hmem/hmem.c
@@ -16,7 +16,6 @@ static int dax_hmem_probe(struct platform_device *pdev)
        struct dax_region *dax_region;
        struct memregion_info *mri;
        struct dev_dax_data data;
-       struct dev_dax *dev_dax;

/*

         * @region_idle == true indicates that an administrative agent
@@ -38,13 +37,8 @@ static int dax_hmem_probe(struct platform_device *pdev)
                .id = -1,
                .size = region_idle ? 0 : range_len(&mri->range),
        };
-       dev_dax = devm_create_dev_dax(&data);
-       if (IS_ERR(dev_dax))
-               return PTR_ERR(dev_dax);

- /* child dev_dax instances now own the lifetime of the dax_region */

-       dax_region_put(dax_region);
-       return 0;
+       return PTR_ERR_OR_ZERO(devm_create_dev_dax(&data));
  }

static struct platform_driver dax_hmem_driver = {

diff --git a/drivers/dax/pmem.c b/drivers/dax/pmem.c
index f050ea78bb83..ae0cb113a5d3 100644
--- a/drivers/dax/pmem.c
+++ b/drivers/dax/pmem.c
@@ -13,7 +13,6 @@ static struct dev_dax *__dax_pmem_probe(struct device *dev)
        int rc, id, region_id;
        resource_size_t offset;
        struct nd_pfn_sb *pfn_sb;
-       struct dev_dax *dev_dax;
        struct dev_dax_data data;
        struct nd_namespace_io *nsio;
        struct dax_region *dax_region;
@@ -65,12 +64,8 @@ static struct dev_dax *__dax_pmem_probe(struct device *dev)
                .pgmap = &pgmap,
                .size = range_len(&range),
        };
-       dev_dax = devm_create_dev_dax(&data);

- /* child dev_dax instances now own the lifetime of the dax_region */

-       dax_region_put(dax_region);
-
-       return dev_dax;
+       return devm_create_dev_dax(&data);
  }

static int dax_pmem_probe(struct device *dev)