/dev/mem: make mem_class a static const structure

Now that the driver core allows for struct class to be in read-only
memory, move the mem_class structure to be declared at build time
placing it into read-only memory, instead of having to be dynamically
allocated at load time.

Cc: Arnd Bergmann <arnd@arndb.de>
Suggested-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Ivan Orlov <ivan.orlov0322@gmail.com>
Link: https://lore.kernel.org/r/20230620143751.578239-13-gregkh@linuxfoundation.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/char/mem.c b/drivers/char/mem.c
index f494d31..2f94452 100644 (file)
--- a/drivers/char/mem.c
+++ b/drivers/char/mem.c
@@ -753,20 +753,23 @@ static char *mem_devnode(const struct device *dev, umode_t *mode)
        return NULL;
 }
 
-static struct class *mem_class;
+static const struct class mem_class = {
+       .name           = "mem",
+       .devnode        = mem_devnode,
+};
 
 static int __init chr_dev_init(void)
 {
+       int retval;
        int minor;
 
        if (register_chrdev(MEM_MAJOR, "mem", &memory_fops))
                printk("unable to get major %d for memory devs\n", MEM_MAJOR);
 
-       mem_class = class_create("mem");
-       if (IS_ERR(mem_class))
-               return PTR_ERR(mem_class);
+       retval = class_register(&mem_class);
+       if (retval)
+               return retval;
 
-       mem_class->devnode = mem_devnode;
        for (minor = 1; minor < ARRAY_SIZE(devlist); minor++) {
                if (!devlist[minor].name)
                        continue;
@@ -777,7 +780,7 @@ static int __init chr_dev_init(void)
                if ((minor == DEVPORT_MINOR) && !arch_has_dev_port())
                        continue;
 
-               device_create(mem_class, NULL, MKDEV(MEM_MAJOR, minor),
+               device_create(&mem_class, NULL, MKDEV(MEM_MAJOR, minor),
                              NULL, devlist[minor].name);
        }