[PATCH 5/5] drivers: char: Replace bit operation functions with IDA allocator.

From: Varsha Rao
Date: Fri Apr 07 2017 - 07:35:03 EST


Replace bit operation functions with IDA allocator functions. As IDA
allocation is simpler.

Signed-off-by: Varsha Rao <rvarsha016@xxxxxxxxx>
---
drivers/char/misc.c | 16 ++++++++++------
1 file changed, 10 insertions(+), 6 deletions(-)

diff --git a/drivers/char/misc.c b/drivers/char/misc.c
index c9cd1ea..5786281 100644
--- a/drivers/char/misc.c
+++ b/drivers/char/misc.c
@@ -60,7 +60,7 @@ static DEFINE_MUTEX(misc_mtx);
* Assigned numbers, used for dynamic minors
*/
#define DYNAMIC_MINORS 64 /* like dynamic majors */
-static DECLARE_BITMAP(misc_minors, DYNAMIC_MINORS);
+static DEFINE_IDA(misc_minors_ida);

#ifdef CONFIG_PROC_FS
static void *misc_seq_start(struct seq_file *seq, loff_t *pos)
@@ -193,14 +193,18 @@ int misc_register(struct miscdevice *misc)
mutex_lock(&misc_mtx);

if (is_dynamic) {
- int i = find_first_zero_bit(misc_minors, DYNAMIC_MINORS);
+ int i = ida_simple_get(&misc_minors_ida, 0,
+ DYNAMIC_MINORS, GFP_KERNEL);

if (i >= DYNAMIC_MINORS) {
err = -EBUSY;
goto out;
- }
+ } else if (i < 0) {
+ err = i;
+ goto out;
+ } else {
misc->minor = DYNAMIC_MINORS - i - 1;
- set_bit(i, misc_minors);
+ }
} else {
struct miscdevice *c;

@@ -222,7 +226,7 @@ int misc_register(struct miscdevice *misc)
int i = DYNAMIC_MINORS - misc->minor - 1;

if (i < DYNAMIC_MINORS && i >= 0)
- clear_bit(i, misc_minors);
+ ida_simple_remove(&misc_minors_ida, i);
misc->minor = MISC_DYNAMIC_MINOR;
}
err = PTR_ERR(misc->this_device);
@@ -258,7 +262,7 @@ void misc_deregister(struct miscdevice *misc)
list_del(&misc->list);
device_destroy(misc_class, MKDEV(MISC_MAJOR, misc->minor));
if (i < DYNAMIC_MINORS && i >= 0)
- clear_bit(i, misc_minors);
+ ida_simple_remove(&misc_minors_ida, i);
mutex_unlock(&misc_mtx);
}

--
2.9.3