From: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Date: Tue, 19 Apr 2022 13:34:31 +0200
Subject: vdpa: Use helper for safer setting of driver_override
Patch-mainline: v5.19-rc1
Git-commit: 240bf4e665741241983580812a2be1b033f120ee
References: jsc#PED-1549

Use a helper to set driver_override to the reduce amount of duplicated
code.

Acked-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Link: https://lore.kernel.org/r/20220419113435.246203-9-krzysztof.kozlowski@linaro.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Acked-by: Thomas Bogendoerfer <tbogendoerfer@suse.de>
---
 drivers/vdpa/vdpa.c  |   29 ++++-------------------------
 include/linux/vdpa.h |    4 +++-
 2 files changed, 7 insertions(+), 26 deletions(-)

--- a/drivers/vdpa/vdpa.c
+++ b/drivers/vdpa/vdpa.c
@@ -77,32 +77,11 @@ static ssize_t driver_override_store(str
 				     const char *buf, size_t count)
 {
 	struct vdpa_device *vdev = dev_to_vdpa(dev);
-	const char *driver_override, *old;
-	char *cp;
+	int ret;
 
-	/* We need to keep extra room for a newline */
-	if (count >= (PAGE_SIZE - 1))
-		return -EINVAL;
-
-	driver_override = kstrndup(buf, count, GFP_KERNEL);
-	if (!driver_override)
-		return -ENOMEM;
-
-	cp = strchr(driver_override, '\n');
-	if (cp)
-		*cp = '\0';
-
-	device_lock(dev);
-	old = vdev->driver_override;
-	if (strlen(driver_override)) {
-		vdev->driver_override = driver_override;
-	} else {
-		kfree(driver_override);
-		vdev->driver_override = NULL;
-	}
-	device_unlock(dev);
-
-	kfree(old);
+	ret = driver_set_override(dev, &vdev->driver_override, buf, count);
+	if (ret)
+		return ret;
 
 	return count;
 }
--- a/include/linux/vdpa.h
+++ b/include/linux/vdpa.h
@@ -64,7 +64,9 @@ struct vdpa_mgmt_dev;
  * struct vdpa_device - representation of a vDPA device
  * @dev: underlying device
  * @dma_dev: the actual device that is performing DMA
- * @driver_override: driver name to force a match
+ * @driver_override: driver name to force a match; do not set directly,
+ *                   because core frees it; use driver_set_override() to
+ *                   set or clear it.
  * @config: the configuration ops for this device.
  * @cf_lock: Protects get and set access to configuration layout.
  * @index: device index