cxl/region: Factor out code to find the root decoder

In function cxl_add_to_region() there is code to determine the root
decoder associated to an endpoint decoder. Factor out that code for
later reuse. This has the benefit of reducing cxl_add_to_region()'s
function complexity.

The reference count must be decremented after using the root decoder.
cxl_find_root_decoder() is paired with the put_cxl_root_decoder
cleanup helper that can be used for this.

[dj: Fixed up "obj __free(...) = NULL" pattern]

Signed-off-by: Robert Richter <rrichter@amd.com>
Reviewed-by: Gregory Price <gourry@gourry.net>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Reviewed-by: Dave Jiang <dave.jiang@intel.com>
Reviewed-by: Dan Williams <dan.j.williams@intel.com>
Reviewed-by: Alison Schofield <alison.schofield@intel.com>
Reviewed-by: "Fabio M. De Francesco" <fabio.m.de.francesco@linux.intel.com>
Tested-by: Gregory Price <gourry@gourry.net>
Acked-by: Dan Williams <dan.j.williams@intel.com>
Link: https://patch.msgid.link/20250509150700.2817697-10-rrichter@amd.com
Signed-off-by: Dave Jiang <dave.jiang@intel.com>

diff --git a/drivers/cxl/core/region.c b/drivers/cxl/core/region.c
index b78f195194697c427c140955ba51b70592d0da30..e76f1cf2e7909f5a7d6ec4b5fb1349f867fbc475 100644 (file)
--- a/drivers/cxl/core/region.c
+++ b/drivers/cxl/core/region.c
@@ -3216,6 +3216,29 @@ static int match_root_decoder_by_range(struct device *dev,
        return range_contains(r1, r2);
 }
 
+static struct cxl_root_decoder *
+cxl_find_root_decoder(struct cxl_endpoint_decoder *cxled)
+{
+       struct cxl_memdev *cxlmd = cxled_to_memdev(cxled);
+       struct cxl_port *port = cxled_to_port(cxled);
+       struct cxl_root *cxl_root __free(put_cxl_root) = find_cxl_root(port);
+       struct cxl_decoder *cxld = &cxled->cxld;
+       struct range *hpa = &cxld->hpa_range;
+       struct device *cxlrd_dev;
+
+       cxlrd_dev = device_find_child(&cxl_root->port.dev, hpa,
+                                     match_root_decoder_by_range);
+       if (!cxlrd_dev) {
+               dev_err(cxlmd->dev.parent,
+                       "%s:%s no CXL window for range %#llx:%#llx\n",
+                       dev_name(&cxlmd->dev), dev_name(&cxld->dev),
+                       cxld->hpa_range.start, cxld->hpa_range.end);
+               return NULL;
+       }
+
+       return to_cxl_root_decoder(cxlrd_dev);
+}
+
 static int match_region_by_range(struct device *dev, const void *data)
 {
        struct cxl_region_params *p;
@@ -3384,29 +3407,17 @@ static struct cxl_region *construct_region(struct cxl_root_decoder *cxlrd,
 
 int cxl_add_to_region(struct cxl_endpoint_decoder *cxled)
 {
-       struct cxl_memdev *cxlmd = cxled_to_memdev(cxled);
-       struct cxl_port *port = cxled_to_port(cxled);
-       struct cxl_root *cxl_root __free(put_cxl_root) = find_cxl_root(port);
        struct range *hpa = &cxled->cxld.hpa_range;
-       struct cxl_decoder *cxld = &cxled->cxld;
-       struct device *cxlrd_dev, *region_dev;
-       struct cxl_root_decoder *cxlrd;
+       struct device *region_dev;
        struct cxl_region_params *p;
        struct cxl_region *cxlr;
        bool attach = false;
        int rc;
 
-       cxlrd_dev = device_find_child(&cxl_root->port.dev, &cxld->hpa_range,
-                                     match_root_decoder_by_range);
-       if (!cxlrd_dev) {
-               dev_err(cxlmd->dev.parent,
-                       "%s:%s no CXL window for range %#llx:%#llx\n",
-                       dev_name(&cxlmd->dev), dev_name(&cxld->dev),
-                       cxld->hpa_range.start, cxld->hpa_range.end);
+       struct cxl_root_decoder *cxlrd __free(put_cxl_root_decoder) =
+               cxl_find_root_decoder(cxled);
+       if (!cxlrd)
                return -ENXIO;
-       }
-
-       cxlrd = to_cxl_root_decoder(cxlrd_dev);
 
        /*
         * Ensure that if multiple threads race to construct_region() for @hpa
@@ -3424,7 +3435,7 @@ int cxl_add_to_region(struct cxl_endpoint_decoder *cxled)
 
        rc = PTR_ERR_OR_ZERO(cxlr);
        if (rc)
-               goto out;
+               return rc;
 
        attach_target(cxlr, cxled, -1, TASK_UNINTERRUPTIBLE);
 
@@ -3445,8 +3456,7 @@ int cxl_add_to_region(struct cxl_endpoint_decoder *cxled)
        }
 
        put_device(region_dev);
-out:
-       put_device(cxlrd_dev);
+
        return rc;
 }
 EXPORT_SYMBOL_NS_GPL(cxl_add_to_region, "CXL");

diff --git a/drivers/cxl/cxl.h b/drivers/cxl/cxl.h
index c3f50f2d5933a4bcf2a76b26582d38c11f9258d4..371f9dcfb61a9dc076f936ac43a369d577f915a0 100644 (file)
--- a/drivers/cxl/cxl.h
+++ b/drivers/cxl/cxl.h
@@ -740,6 +740,7 @@ struct cxl_root *find_cxl_root(struct cxl_port *port);
 
 DEFINE_FREE(put_cxl_root, struct cxl_root *, if (_T) put_device(&_T->port.dev))
 DEFINE_FREE(put_cxl_port, struct cxl_port *, if (!IS_ERR_OR_NULL(_T)) put_device(&_T->dev))
+DEFINE_FREE(put_cxl_root_decoder, struct cxl_root_decoder *, if (!IS_ERR_OR_NULL(_T)) put_device(&_T->cxlsd.cxld.dev))
 
 int devm_cxl_enumerate_ports(struct cxl_memdev *cxlmd);
 void cxl_bus_rescan(void);