chardev: Switch to guard(mutex) and __free(kfree)

Instead of using the 'goto label; mutex_unlock()' pattern use
'guard(mutex)' which will release the mutex when it goes out of scope.
Use the __free(kfree) cleanup to replace instances of manually
calling kfree(). Also make some code path simplifications that this
allows.

Signed-off-by: chen zhang <chenzhang@kylinos.cn>
Link: https://patch.msgid.link/20251215111500.159243-1-chenzhang@kylinos.cn
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Christian Brauner <brauner@kernel.org>

diff --git a/fs/char_dev.c b/fs/char_dev.c
index 84a5a0699373cdf6312cf04c96b2a3d66c72fee8..bf7b32650e54a352c8d5d33f0159a67807ad54fc 100644 (file)
--- a/fs/char_dev.c
+++ b/fs/char_dev.c
@@ -10,6 +10,7 @@
 #include <linux/kdev_t.h>
 #include <linux/slab.h>
 #include <linux/string.h>
+#include <linux/cleanup.h>
 
 #include <linux/major.h>
 #include <linux/errno.h>
@@ -97,7 +98,8 @@ static struct char_device_struct *
 __register_chrdev_region(unsigned int major, unsigned int baseminor,
                           int minorct, const char *name)
 {
-       struct char_device_struct *cd, *curr, *prev = NULL;
+       struct char_device_struct *cd __free(kfree) = NULL;
+       struct char_device_struct *curr, *prev = NULL;
        int ret;
        int i;
 
@@ -117,14 +119,14 @@ __register_chrdev_region(unsigned int major, unsigned int baseminor,
        if (cd == NULL)
                return ERR_PTR(-ENOMEM);
 
-       mutex_lock(&chrdevs_lock);
+       guard(mutex)(&chrdevs_lock);
 
        if (major == 0) {
                ret = find_dynamic_major();
                if (ret < 0) {
                        pr_err("CHRDEV \"%s\" dynamic allocation region is full\n",
                               name);
-                       goto out;
+                       return ERR_PTR(ret);
                }
                major = ret;
        }
@@ -144,7 +146,7 @@ __register_chrdev_region(unsigned int major, unsigned int baseminor,
                if (curr->baseminor >= baseminor + minorct)
                        break;
 
-               goto out;
+               return ERR_PTR(ret);
        }
 
        cd->major = major;
@@ -160,12 +162,7 @@ __register_chrdev_region(unsigned int major, unsigned int baseminor,
                prev->next = cd;
        }
 
-       mutex_unlock(&chrdevs_lock);
-       return cd;
-out:
-       mutex_unlock(&chrdevs_lock);
-       kfree(cd);
-       return ERR_PTR(ret);
+       return_ptr(cd);
 }
 
 static struct char_device_struct *