s390/cio: Use driver_set_override() instead of open-coding

Use a helper to set driver_override to the reduce amount of duplicated
code.  Make the driver_override field const char, because it is not
modified by the core and it matches other subsystems.

Acked-by: Vineeth Vijayan <vneethv@linux.ibm.com>
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Link: https://lore.kernel.org/r/20220419113435.246203-7-krzysztof.kozlowski@linaro.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/s390/cio/cio.h b/drivers/s390/cio/cio.h
index 1cb9daf..fa8df50 100644 (file)
--- a/drivers/s390/cio/cio.h
+++ b/drivers/s390/cio/cio.h
@@ -103,7 +103,11 @@ struct subchannel {
        struct work_struct todo_work;
        struct schib_config config;
        u64 dma_mask;
-       char *driver_override; /* Driver name to force a match */
+       /*
+        * Driver name to force a match.  Do not set directly, because core
+        * frees it.  Use driver_set_override() to set or clear it.
+        */
+       const char *driver_override;
 } __attribute__ ((aligned(8)));
 
 DECLARE_PER_CPU_ALIGNED(struct irb, cio_irb);

diff --git a/drivers/s390/cio/css.c b/drivers/s390/cio/css.c
index fa82933..913b6dd 100644 (file)
--- a/drivers/s390/cio/css.c
+++ b/drivers/s390/cio/css.c
@@ -338,31 +338,11 @@ static ssize_t driver_override_store(struct device *dev,
                                     const char *buf, size_t count)
 {
        struct subchannel *sch = to_subchannel(dev);
-       char *driver_override, *old, *cp;
-
-       /* 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 = sch->driver_override;
-       if (strlen(driver_override)) {
-               sch->driver_override = driver_override;
-       } else {
-               kfree(driver_override);
-               sch->driver_override = NULL;
-       }
-       device_unlock(dev);
+       int ret;
 
-       kfree(old);
+       ret = driver_set_override(dev, &sch->driver_override, buf, count);
+       if (ret)
+               return ret;
 
        return count;
 }