[PATCH v2 27/28] cxl/pmem: Fix offline_nvdimm_bus() to offline by bridge

[Dan Williams <dan.j.williams@xxxxxxxxx>]

Be careful to only disable cxl_pmem objects related to a given
cxl_nvdimm_bridge. Otherwise, offline_nvdimm_bus() reaches across CXL
domains and disables more than is expected.

Fixes: 21083f51521f ("cxl/pmem: Register 'pmem' / cxl_nvdimm devices")
Signed-off-by: Dan Williams <dan.j.williams@xxxxxxxxx>
---
 drivers/cxl/cxl.h  |    1 +
 drivers/cxl/pmem.c |   21 +++++++++++++++++----
 2 files changed, 18 insertions(+), 4 deletions(-)

diff --git a/drivers/cxl/cxl.h b/drivers/cxl/cxl.h
index 9aedd471193a..a32093602df9 100644
--- a/drivers/cxl/cxl.h
+++ b/drivers/cxl/cxl.h
@@ -418,6 +418,7 @@ struct cxl_nvdimm_bridge {
 struct cxl_nvdimm {
 	struct device dev;
 	struct cxl_memdev *cxlmd;
+	struct cxl_nvdimm_bridge *bridge;
 };
 
 /**
diff --git a/drivers/cxl/pmem.c b/drivers/cxl/pmem.c
index 0aaa70b4e0f7..b271f6e90b91 100644
--- a/drivers/cxl/pmem.c
+++ b/drivers/cxl/pmem.c
@@ -26,7 +26,10 @@ static void clear_exclusive(void *cxlds)
 
 static void unregister_nvdimm(void *nvdimm)
 {
+	struct cxl_nvdimm *cxl_nvd = nvdimm_provider_data(nvdimm);
+
 	nvdimm_delete(nvdimm);
+	cxl_nvd->bridge = NULL;
 }
 
 static int cxl_nvdimm_probe(struct device *dev)
@@ -66,6 +69,7 @@ static int cxl_nvdimm_probe(struct device *dev)
 	}
 
 	dev_set_drvdata(dev, nvdimm);
+	cxl_nvd->bridge = cxl_nvb;
 	rc = devm_add_action_or_reset(dev, unregister_nvdimm, nvdimm);
 out:
 	device_unlock(&cxl_nvb->dev);
@@ -204,15 +208,23 @@ static bool online_nvdimm_bus(struct cxl_nvdimm_bridge *cxl_nvb)
 	return cxl_nvb->nvdimm_bus != NULL;
 }
 
-static int cxl_nvdimm_release_driver(struct device *dev, void *data)
+static int cxl_nvdimm_release_driver(struct device *dev, void *cxl_nvb)
 {
+	struct cxl_nvdimm *cxl_nvd;
+
 	if (!is_cxl_nvdimm(dev))
 		return 0;
+
+	cxl_nvd = to_cxl_nvdimm(dev);
+	if (cxl_nvd->bridge != cxl_nvb)
+		return 0;
+
 	device_release_driver(dev);
 	return 0;
 }
 
-static void offline_nvdimm_bus(struct nvdimm_bus *nvdimm_bus)
+static void offline_nvdimm_bus(struct cxl_nvdimm_bridge *cxl_nvb,
+			       struct nvdimm_bus *nvdimm_bus)
 {
 	if (!nvdimm_bus)
 		return;
@@ -222,7 +234,8 @@ static void offline_nvdimm_bus(struct nvdimm_bus *nvdimm_bus)
 	 * nvdimm_bus_unregister() rips the nvdimm objects out from
 	 * underneath them.
 	 */
-	bus_for_each_dev(&cxl_bus_type, NULL, NULL, cxl_nvdimm_release_driver);
+	bus_for_each_dev(&cxl_bus_type, NULL, cxl_nvb,
+			 cxl_nvdimm_release_driver);
 	nvdimm_bus_unregister(nvdimm_bus);
 }
 
@@ -260,7 +273,7 @@ static void cxl_nvb_update_state(struct work_struct *work)
 
 		dev_dbg(&cxl_nvb->dev, "rescan: %d\n", rc);
 	}
-	offline_nvdimm_bus(victim_bus);
+	offline_nvdimm_bus(cxl_nvb, victim_bus);
 
 	put_device(&cxl_nvb->dev);
 }