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path: root/drivers/char/misc.c
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Diffstat (limited to 'drivers/char/misc.c')
-rw-r--r--drivers/char/misc.c39
1 files changed, 30 insertions, 9 deletions
diff --git a/drivers/char/misc.c b/drivers/char/misc.c
index 541edc26ec89..2cf595d2e10b 100644
--- a/drivers/char/misc.c
+++ b/drivers/char/misc.c
@@ -63,16 +63,30 @@ static DEFINE_MUTEX(misc_mtx);
#define DYNAMIC_MINORS 128 /* like dynamic majors */
static DEFINE_IDA(misc_minors_ida);
-static int misc_minor_alloc(void)
+static int misc_minor_alloc(int minor)
{
- int ret;
-
- ret = ida_alloc_max(&misc_minors_ida, DYNAMIC_MINORS - 1, GFP_KERNEL);
- if (ret >= 0) {
- ret = DYNAMIC_MINORS - ret - 1;
+ int ret = 0;
+
+ if (minor == MISC_DYNAMIC_MINOR) {
+ /* allocate free id */
+ ret = ida_alloc_max(&misc_minors_ida, DYNAMIC_MINORS - 1, GFP_KERNEL);
+ if (ret >= 0) {
+ ret = DYNAMIC_MINORS - ret - 1;
+ } else {
+ ret = ida_alloc_range(&misc_minors_ida, MISC_DYNAMIC_MINOR + 1,
+ MINORMASK, GFP_KERNEL);
+ }
} else {
- ret = ida_alloc_range(&misc_minors_ida, MISC_DYNAMIC_MINOR + 1,
- MINORMASK, GFP_KERNEL);
+ /* specific minor, check if it is in dynamic or misc dynamic range */
+ if (minor < DYNAMIC_MINORS) {
+ minor = DYNAMIC_MINORS - minor - 1;
+ ret = ida_alloc_range(&misc_minors_ida, minor, minor, GFP_KERNEL);
+ } else if (minor > MISC_DYNAMIC_MINOR) {
+ ret = ida_alloc_range(&misc_minors_ida, minor, minor, GFP_KERNEL);
+ } else {
+ /* case of non-dynamic minors, no need to allocate id */
+ ret = 0;
+ }
}
return ret;
}
@@ -219,7 +233,7 @@ int misc_register(struct miscdevice *misc)
mutex_lock(&misc_mtx);
if (is_dynamic) {
- int i = misc_minor_alloc();
+ int i = misc_minor_alloc(misc->minor);
if (i < 0) {
err = -EBUSY;
@@ -228,6 +242,7 @@ int misc_register(struct miscdevice *misc)
misc->minor = i;
} else {
struct miscdevice *c;
+ int i;
list_for_each_entry(c, &misc_list, list) {
if (c->minor == misc->minor) {
@@ -235,6 +250,12 @@ int misc_register(struct miscdevice *misc)
goto out;
}
}
+
+ i = misc_minor_alloc(misc->minor);
+ if (i < 0) {
+ err = -EBUSY;
+ goto out;
+ }
}
dev = MKDEV(MISC_MAJOR, misc->minor);