[PATCH 5/6] cxl: Pass fops and shutdown to memdev creation

[Ben Widawsky <ben.widawsky@intel.com>]

Drivers that use cxl_core for registering a cxl_memdev will likely
require synchronization with the core for shutdown so as to not race
against the device going away. The main example currently is with the
ioctl interface. Through the duration of the ioctl it's expected that
the underlying memdev will not disappear.

Additionally, it may be desirable to have the fops be passed along as
well for drivers which do not want the standard handler for the
character device's ioctl.

As memdev is being migrated to core, this separation must be made.

Signed-off-by: Ben Widawsky <ben.widawsky@intel.com>
---
 drivers/cxl/mem.h |  2 ++
 drivers/cxl/pci.c | 23 +++++++++++++++--------
 2 files changed, 17 insertions(+), 8 deletions(-)

diff --git a/drivers/cxl/mem.h b/drivers/cxl/mem.h
index 2092f86beeb8..2b7481376621 100644
--- a/drivers/cxl/mem.h
+++ b/drivers/cxl/mem.h
@@ -42,12 +42,14 @@ extern int cxl_mem_major;
  * @cdev: char dev core object for ioctl operations
  * @cxlm: pointer to the parent device driver data
  * @id: id number of this memdev instance.
+ * @shutdown: Optional function to call on memory device shutdown.
  */
 struct cxl_memdev {
 	struct device dev;
 	struct cdev cdev;
 	struct cxl_mem *cxlm;
 	int id;
+	void (*shutdown)(struct cxl_memdev *cxlmd);
 };
 
 /**
diff --git a/drivers/cxl/pci.c b/drivers/cxl/pci.c
index 6f10b19c9c83..418ae0eac188 100644
--- a/drivers/cxl/pci.c
+++ b/drivers/cxl/pci.c
@@ -1293,11 +1293,13 @@ static void cxl_memdev_unregister(void *_cxlmd)
 	struct device *dev = &cxlmd->dev;
 
 	cdev_device_del(&cxlmd->cdev, dev);
-	cxl_memdev_shutdown(cxlmd);
+	if (cxlmd->shutdown)
+		cxlmd->shutdown(cxlmd);
 	put_device(dev);
 }
 
-static struct cxl_memdev *cxl_memdev_alloc(struct cxl_mem *cxlm)
+static struct cxl_memdev *cxl_memdev_alloc(struct cxl_mem *cxlm,
+					   const struct file_operations *fops)
 {
 	struct pci_dev *pdev = cxlm->pdev;
 	struct cxl_memdev *cxlmd;
@@ -1323,7 +1325,7 @@ static struct cxl_memdev *cxl_memdev_alloc(struct cxl_mem *cxlm)
 	device_set_pm_not_required(dev);
 
 	cdev = &cxlmd->cdev;
-	cdev_init(cdev, &cxl_memdev_fops);
+	cdev_init(cdev, fops);
 	return cxlmd;
 
 err:
@@ -1331,15 +1333,17 @@ static struct cxl_memdev *cxl_memdev_alloc(struct cxl_mem *cxlm)
 	return ERR_PTR(rc);
 }
 
-static struct cxl_memdev *devm_cxl_add_memdev(struct device *host,
-					      struct cxl_mem *cxlm)
+static struct cxl_memdev *
+devm_cxl_add_memdev(struct device *host, struct cxl_mem *cxlm,
+		    const struct file_operations *fops,
+		    void (*shutdown)(struct cxl_memdev *cxlmd))
 {
 	struct cxl_memdev *cxlmd;
 	struct device *dev;
 	struct cdev *cdev;
 	int rc;
 
-	cxlmd = cxl_memdev_alloc(cxlm);
+	cxlmd = cxl_memdev_alloc(cxlm, fops);
 	if (IS_ERR(cxlmd))
 		return cxlmd;
 
@@ -1362,6 +1366,7 @@ static struct cxl_memdev *devm_cxl_add_memdev(struct device *host,
 	rc = devm_add_action_or_reset(host, cxl_memdev_unregister, cxlmd);
 	if (rc)
 		return ERR_PTR(rc);
+	cxlmd->shutdown = shutdown;
 	return cxlmd;
 
 err:
@@ -1369,7 +1374,8 @@ static struct cxl_memdev *devm_cxl_add_memdev(struct device *host,
 	 * The cdev was briefly live, shutdown any ioctl operations that
 	 * saw that state.
 	 */
-	cxl_memdev_shutdown(cxlmd);
+	if (shutdown)
+		shutdown(cxlmd);
 	put_device(dev);
 	return ERR_PTR(rc);
 }
@@ -1610,7 +1616,8 @@ static int cxl_mem_probe(struct pci_dev *pdev, const struct pci_device_id *id)
 	if (rc)
 		return rc;
 
-	cxlmd = devm_cxl_add_memdev(&pdev->dev, cxlm);
+	cxlmd = devm_cxl_add_memdev(&pdev->dev, cxlm, &cxl_memdev_fops,
+				    cxl_memdev_shutdown);
 	if (IS_ERR(cxlmd))
 		return PTR_ERR(cxlmd);
 
-- 
2.32.0