[PATCH 3/7] cxl/region: Add cxl_memdev_active_region()

[Davidlohr Bueso <dave@stgolabs.net>]

Track all regions associated to a memdev in order to
tell if the device might be in active use.

Signed-off-by: Davidlohr Bueso <dave@stgolabs.net>
---
 drivers/cxl/core/memdev.c |  1 +
 drivers/cxl/core/region.c | 33 +++++++++++++++++++++++++++++++--
 drivers/cxl/cxl.h         |  6 ++++++
 drivers/cxl/cxlmem.h      |  4 ++++
 4 files changed, 42 insertions(+), 2 deletions(-)

diff --git a/drivers/cxl/core/memdev.c b/drivers/cxl/core/memdev.c
index 47cc625bb1b0..68c0ab06b999 100644
--- a/drivers/cxl/core/memdev.c
+++ b/drivers/cxl/core/memdev.c
@@ -306,6 +306,7 @@ static struct cxl_memdev *cxl_memdev_alloc(struct cxl_dev_state *cxlds,
 	dev->type = &cxl_memdev_type;
 	device_set_pm_not_required(dev);
 	INIT_WORK(&cxlmd->detach_work, detach_memdev);
+	INIT_LIST_HEAD(&cxlmd->region_list);
 
 	cdev = &cxlmd->cdev;
 	cdev_init(cdev, fops);
diff --git a/drivers/cxl/core/region.c b/drivers/cxl/core/region.c
index f29028148806..cea9de6457b9 100644
--- a/drivers/cxl/core/region.c
+++ b/drivers/cxl/core/region.c
@@ -1730,7 +1730,10 @@ void cxl_decoder_kill_region(struct cxl_endpoint_decoder *cxled)
 {
 	down_write(&cxl_region_rwsem);
 	cxled->mode = CXL_DECODER_DEAD;
-	cxl_region_detach(cxled);
+	if (!cxl_region_detach(cxled)) {
+		struct cxl_region *cxlr = cxled->cxld.region;
+		list_del(&cxlr->node);
+	}
 	up_write(&cxl_region_rwsem);
 }
 
@@ -1749,8 +1752,12 @@ static int attach_target(struct cxl_region *cxlr,
 
 	down_read(&cxl_dpa_rwsem);
 	rc = cxl_region_attach(cxlr, cxled, pos);
-	if (rc == 0)
+	if (rc == 0) {
+		struct cxl_memdev *cxlmd = cxled_to_memdev(cxled);
+
 		set_bit(CXL_REGION_F_INCOHERENT, &cxlr->flags);
+		list_add_tail(&cxlr->node, &cxlmd->region_list);
+	}
 	up_read(&cxl_dpa_rwsem);
 	up_write(&cxl_region_rwsem);
 	return rc;
@@ -1778,6 +1785,8 @@ static int detach_target(struct cxl_region *cxlr, int pos)
 	}
 
 	rc = cxl_region_detach(p->targets[pos]);
+	if (rc == 0)
+		list_del(&cxlr->node);
 out:
 	up_write(&cxl_region_rwsem);
 	return rc;
@@ -2654,6 +2663,26 @@ int cxl_add_to_region(struct cxl_port *root, struct cxl_endpoint_decoder *cxled)
 }
 EXPORT_SYMBOL_NS_GPL(cxl_add_to_region, CXL);
 
+bool cxl_memdev_active_region(struct cxl_memdev *cxlmd)
+{
+	bool ret = false;
+	struct cxl_region *cxlr;
+
+	down_read(&cxl_region_rwsem);
+	list_for_each_entry(cxlr, &cxlmd->region_list, node) {
+		struct cxl_region_params *p = &cxlr->params;
+
+		if (p->state >= CXL_CONFIG_ACTIVE) {
+			ret = true;
+			break;
+		}
+	}
+	up_read(&cxl_region_rwsem);
+
+	return ret;
+}
+EXPORT_SYMBOL_NS_GPL(cxl_memdev_active_region, CXL);
+
 static int cxl_region_invalidate_memregion(struct cxl_region *cxlr)
 {
 	if (!test_bit(CXL_REGION_F_INCOHERENT, &cxlr->flags))
diff --git a/drivers/cxl/cxl.h b/drivers/cxl/cxl.h
index b834e55375e3..e211241b079b 100644
--- a/drivers/cxl/cxl.h
+++ b/drivers/cxl/cxl.h
@@ -502,6 +502,7 @@ struct cxl_region {
 	struct cxl_pmem_region *cxlr_pmem;
 	unsigned long flags;
 	struct cxl_region_params params;
+	struct list_head node;
 };
 
 struct cxl_nvdimm_bridge {
@@ -773,6 +774,7 @@ struct cxl_pmem_region *to_cxl_pmem_region(struct device *dev);
 int cxl_add_to_region(struct cxl_port *root,
 		      struct cxl_endpoint_decoder *cxled);
 struct cxl_dax_region *to_cxl_dax_region(struct device *dev);
+bool cxl_memdev_active_region(struct cxl_memdev *cxlmd);
 #else
 static inline bool is_cxl_pmem_region(struct device *dev)
 {
@@ -791,6 +793,10 @@ static inline struct cxl_dax_region *to_cxl_dax_region(struct device *dev)
 {
 	return NULL;
 }
+static inline bool cxl_memdev_active_region(struct cxl_memdev *cxlmd)
+{
+	return false;
+}
 #endif
 
 /*
diff --git a/drivers/cxl/cxlmem.h b/drivers/cxl/cxlmem.h
index 934076254d52..4e31f3234519 100644
--- a/drivers/cxl/cxlmem.h
+++ b/drivers/cxl/cxlmem.h
@@ -5,6 +5,7 @@
 #include <uapi/linux/cxl_mem.h>
 #include <linux/cdev.h>
 #include <linux/uuid.h>
+#include <linux/list.h>
 #include "cxl.h"
 
 /* CXL 2.0 8.2.8.5.1.1 Memory Device Status Register */
@@ -40,6 +41,8 @@
  * @cxl_nvd: optional bridge to an nvdimm if the device supports pmem
  * @id: id number of this memdev instance.
  * @depth: endpoint port depth
+ * @region_list: List of regions that have as target the endpoint
+ *               decoder associated with this memdev
  */
 struct cxl_memdev {
 	struct device dev;
@@ -50,6 +53,7 @@ struct cxl_memdev {
 	struct cxl_nvdimm *cxl_nvd;
 	int id;
 	int depth;
+	struct list_head region_list;
 };
 
 static inline struct cxl_memdev *to_cxl_memdev(struct device *dev)
-- 
2.39.2