cxl/region: Drop goto pattern of construct_region()

Some operations need to be protected by the cxl_region_rwsem in
construct_region(). Currently, construct_region() uses down_write() and
up_write() for the cxl_region_rwsem locking, so there is a goto pattern
after down_write() invoked to release cxl_region_rwsem.

construct region() can be optimized to remove the goto pattern. The
changes are creating a new function called __construct_region() which
will include all checking and operations protected by the
cxl_region_rwsem, and using guard(rwsem_write) to replace down_write()
and up_write() in __construct_region().

Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Reviewed-by: Dave Jiang <dave.jiang@intel.com>
Reviewed-by: Alison Schofield <alison.schofield@intel.com>
Reviewed-by: Dan Williams <dan.j.williams@intel.com>
Reviewed-by: Ira Weiny <ira.weiny@intel.com>
Acked-by: Davidlohr Bueso <dave@stgolabs.net>
Signed-off-by: Li Ming <ming.li@zohomail.com>
Link: https://patch.msgid.link/20250221013205.126419-1-ming.li@zohomail.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 320a3f2181315515249591210738f606803af854..a750107a3bfffaf549b4cb12423d9d94d7d6a387 100644 (file)
--- a/drivers/cxl/core/region.c
+++ b/drivers/cxl/core/region.c
@@ -3216,49 +3216,31 @@ static int match_region_by_range(struct device *dev, const void *data)
        return 0;
 }
 
-/* Establish an empty region covering the given HPA range */
-static struct cxl_region *construct_region(struct cxl_root_decoder *cxlrd,
-                                          struct cxl_endpoint_decoder *cxled)
+static int __construct_region(struct cxl_region *cxlr,
+                             struct cxl_root_decoder *cxlrd,
+                             struct cxl_endpoint_decoder *cxled)
 {
        struct cxl_memdev *cxlmd = cxled_to_memdev(cxled);
-       struct cxl_port *port = cxlrd_to_port(cxlrd);
        struct range *hpa = &cxled->cxld.hpa_range;
        struct cxl_region_params *p;
-       struct cxl_region *cxlr;
        struct resource *res;
        int rc;
 
-       do {
-               cxlr = __create_region(cxlrd, cxled->mode,
-                                      atomic_read(&cxlrd->region_id));
-       } while (IS_ERR(cxlr) && PTR_ERR(cxlr) == -EBUSY);
-
-       if (IS_ERR(cxlr)) {
-               dev_err(cxlmd->dev.parent,
-                       "%s:%s: %s failed assign region: %ld\n",
-                       dev_name(&cxlmd->dev), dev_name(&cxled->cxld.dev),
-                       __func__, PTR_ERR(cxlr));
-               return cxlr;
-       }
-
-       down_write(&cxl_region_rwsem);
+       guard(rwsem_write)(&cxl_region_rwsem);
        p = &cxlr->params;
        if (p->state >= CXL_CONFIG_INTERLEAVE_ACTIVE) {
                dev_err(cxlmd->dev.parent,
                        "%s:%s: %s autodiscovery interrupted\n",
                        dev_name(&cxlmd->dev), dev_name(&cxled->cxld.dev),
                        __func__);
-               rc = -EBUSY;
-               goto err;
+               return -EBUSY;
        }
 
        set_bit(CXL_REGION_F_AUTO, &cxlr->flags);
 
        res = kmalloc(sizeof(*res), GFP_KERNEL);
-       if (!res) {
-               rc = -ENOMEM;
-               goto err;
-       }
+       if (!res)
+               return -ENOMEM;
 
        *res = DEFINE_RES_MEM_NAMED(hpa->start, range_len(hpa),
                                    dev_name(&cxlr->dev));
@@ -3281,7 +3263,7 @@ static struct cxl_region *construct_region(struct cxl_root_decoder *cxlrd,
 
        rc = sysfs_update_group(&cxlr->dev.kobj, get_cxl_region_target_group());
        if (rc)
-               goto err;
+               return rc;
 
        dev_dbg(cxlmd->dev.parent, "%s:%s: %s %s res: %pr iw: %d ig: %d\n",
                dev_name(&cxlmd->dev), dev_name(&cxled->cxld.dev), __func__,
@@ -3290,14 +3272,39 @@ static struct cxl_region *construct_region(struct cxl_root_decoder *cxlrd,
 
        /* ...to match put_device() in cxl_add_to_region() */
        get_device(&cxlr->dev);
-       up_write(&cxl_region_rwsem);
 
-       return cxlr;
+       return 0;
+}
 
-err:
-       up_write(&cxl_region_rwsem);
-       devm_release_action(port->uport_dev, unregister_region, cxlr);
-       return ERR_PTR(rc);
+/* Establish an empty region covering the given HPA range */
+static struct cxl_region *construct_region(struct cxl_root_decoder *cxlrd,
+                                          struct cxl_endpoint_decoder *cxled)
+{
+       struct cxl_memdev *cxlmd = cxled_to_memdev(cxled);
+       struct cxl_port *port = cxlrd_to_port(cxlrd);
+       struct cxl_region *cxlr;
+       int rc;
+
+       do {
+               cxlr = __create_region(cxlrd, cxled->mode,
+                                      atomic_read(&cxlrd->region_id));
+       } while (IS_ERR(cxlr) && PTR_ERR(cxlr) == -EBUSY);
+
+       if (IS_ERR(cxlr)) {
+               dev_err(cxlmd->dev.parent,
+                       "%s:%s: %s failed assign region: %ld\n",
+                       dev_name(&cxlmd->dev), dev_name(&cxled->cxld.dev),
+                       __func__, PTR_ERR(cxlr));
+               return cxlr;
+       }
+
+       rc = __construct_region(cxlr, cxlrd, cxled);
+       if (rc) {
+               devm_release_action(port->uport_dev, unregister_region, cxlr);
+               return ERR_PTR(rc);
+       }
+
+       return cxlr;
 }
 
 int cxl_add_to_region(struct cxl_port *root, struct cxl_endpoint_decoder *cxled)