drivers: char: mem: Make /dev/mem an optional device

Adds Kconfig option CONFIG_DEVMEM that allows the
/dev/mem device to be disabled.

Option defaults to /dev/mem enabled.

Signed-off-by: Rob Ward <robert.ward114@googlemail.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/char/Kconfig b/drivers/char/Kconfig
index efefd12a0f7bd97b2d6a3970eb068250bce257c2..a4af8221751e4d6905d37cefc628409f1fb30b7e 100644 (file)
--- a/drivers/char/Kconfig
+++ b/drivers/char/Kconfig
@@ -6,6 +6,15 @@ menu "Character devices"
 
 source "drivers/tty/Kconfig"
 
+config DEVMEM
+       bool "/dev/mem virtual device support"
+       default y
+       help
+         Say Y here if you want to support the /dev/mem device.
+         The /dev/mem device is used to access areas of physical
+         memory.
+         When in doubt, say "Y".
+
 config DEVKMEM
        bool "/dev/kmem virtual device support"
        default y

diff --git a/drivers/char/mem.c b/drivers/char/mem.c
index 4c58333b42570d233ccfaa83dac3c67f69e73b49..7d6778437be0df2aa760115daedb412214eec7ce 100644 (file)
--- a/drivers/char/mem.c
+++ b/drivers/char/mem.c
@@ -715,7 +715,7 @@ static int open_port(struct inode *inode, struct file *filp)
 #define open_mem       open_port
 #define open_kmem      open_mem
 
-static const struct file_operations mem_fops = {
+static const struct file_operations __maybe_unused mem_fops = {
        .llseek         = memory_lseek,
        .read           = read_mem,
        .write          = write_mem,
@@ -785,7 +785,9 @@ static const struct memdev {
        const struct file_operations *fops;
        struct backing_dev_info *dev_info;
 } devlist[] = {
+#ifdef CONFIG_DEVMEM
         [1] = { "mem", 0, &mem_fops, &directly_mappable_cdev_bdi },
+#endif
 #ifdef CONFIG_DEVKMEM
         [2] = { "kmem", 0, &kmem_fops, &directly_mappable_cdev_bdi },
 #endif