[PATCH v3 07/11] spi: Use helper for safer setting of driver_override

[Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>]

Use a helper for seting driver_override to reduce amount of duplicated
code.

Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>
---
 drivers/spi/spi.c       | 26 ++++----------------------
 include/linux/spi/spi.h |  2 ++
 2 files changed, 6 insertions(+), 22 deletions(-)

diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c
index 4599b121d744..9d0b11017741 100644
--- a/drivers/spi/spi.c
+++ b/drivers/spi/spi.c
@@ -72,29 +72,11 @@ static ssize_t driver_override_store(struct device *dev,
 				     const char *buf, size_t count)
 {
 	struct spi_device *spi = to_spi_device(dev);
-	const char *end = memchr(buf, '\n', count);
-	const size_t len = end ? end - buf : count;
-	const char *driver_override, *old;
-
-	/* We need to keep extra room for a newline when displaying value */
-	if (len >= (PAGE_SIZE - 1))
-		return -EINVAL;
-
-	driver_override = kstrndup(buf, len, GFP_KERNEL);
-	if (!driver_override)
-		return -ENOMEM;
+	int ret;
 
-	device_lock(dev);
-	old = spi->driver_override;
-	if (len) {
-		spi->driver_override = driver_override;
-	} else {
-		/* Empty string, disable driver override */
-		spi->driver_override = NULL;
-		kfree(driver_override);
-	}
-	device_unlock(dev);
-	kfree(old);
+	ret = driver_set_override(dev, &spi->driver_override, buf, count);
+	if (ret)
+		return ret;
 
 	return count;
 }
diff --git a/include/linux/spi/spi.h b/include/linux/spi/spi.h
index 7ab3fed7b804..f99bbb20dd4b 100644
--- a/include/linux/spi/spi.h
+++ b/include/linux/spi/spi.h
@@ -136,6 +136,8 @@ extern int spi_delay_exec(struct spi_delay *_delay, struct spi_transfer *xfer);
  *	for driver coldplugging, and in uevents used for hotplugging
  * @driver_override: If the name of a driver is written to this attribute, then
  *	the device will bind to the named driver and only the named driver.
+ *	Do not set directly, because core frees it; use driver_set_override() to
+ *	set or clear it.
  * @cs_gpio: LEGACY: gpio number of the chipselect line (optional, -ENOENT when
  *	not using a GPIO line) use cs_gpiod in new drivers by opting in on
  *	the spi_master.
-- 
2.32.0