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

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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>
This commit is contained in:
chen zhang 2025-12-15 19:15:00 +08:00 • committed by Christian Brauner
parent 3f320e5c2e
commit 3685744afa
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GPG key ID: 91C61BC06578DCA2
1 changed files with 7 additions and 10 deletions
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17
fs/char_dev.c
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@ -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 *