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Commit 1f2f38d8 authored by Thadeu Lima de Souza Cascardo's avatar Thadeu Lima de Souza Cascardo Committed by Linus Torvalds
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drivers/char/misc.c: use bitmap/bitops functions for dynamic minor number allocation 



Use DECLARE_BITMAP(), find_first_zero_bit(), set_bit() and clear_bit()
instead of rewriting code to do it with the minor number dynamic
allocation bitmap.

We need to invert the bit position to keep the code behaviour of using the
last minor numbers first, since we don't have a find_last_zero_bit.

Signed-off-by: default avatarThadeu Lima de Souza Cascardo <cascardo@holoscopio.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 4ae717da

drivers/char/misc.c

+9 −13
Original line number Diff line number Diff line
@@ -60,7 +60,7 @@ static DEFINE_MUTEX(misc_mtx); 
 * Assigned numbers, used for dynamic minors

 */

#define DYNAMIC_MINORS 64 /* like dynamic majors */

static unsigned char misc_minors[DYNAMIC_MINORS / 8];

static DECLARE_BITMAP(misc_minors, DYNAMIC_MINORS);



#ifdef CONFIG_PROC_FS

static void *misc_seq_start(struct seq_file *seq, loff_t *pos)
@@ -196,27 +196,23 @@ int misc_register(struct miscdevice * misc) 
	}



	if (misc->minor == MISC_DYNAMIC_MINOR) {

		int i = DYNAMIC_MINORS;

		while (--i >= 0)

			if ( (misc_minors[i>>3] & (1 << (i&7))) == 0)

				break;

		if (i<0) {

		int i = find_first_zero_bit(misc_minors, DYNAMIC_MINORS);

		if (i >= DYNAMIC_MINORS) {

			mutex_unlock(&misc_mtx);

			return -EBUSY;

		}

		misc->minor = i;

		misc->minor = DYNAMIC_MINORS - i - 1;

		set_bit(i, misc_minors);

	}



	if (misc->minor < DYNAMIC_MINORS)

		misc_minors[misc->minor >> 3] |= 1 << (misc->minor & 7);

	dev = MKDEV(MISC_MAJOR, misc->minor);



	misc->this_device = device_create(misc_class, misc->parent, dev,

					  misc, "%s", misc->name);

	if (IS_ERR(misc->this_device)) {

		int i = misc->minor;

		int i = DYNAMIC_MINORS - misc->minor - 1;

		if (i < DYNAMIC_MINORS && i >= 0)

			misc_minors[i>>3] &= ~(1 << (i & 7));

			clear_bit(i, misc_minors);

		err = PTR_ERR(misc->this_device);

		goto out;

	}
@@ -243,7 +239,7 @@ int misc_register(struct miscdevice * misc) 


int misc_deregister(struct miscdevice *misc)

{

	int i = misc->minor;

	int i = DYNAMIC_MINORS - misc->minor - 1;



	if (list_empty(&misc->list))

		return -EINVAL;
@@ -252,7 +248,7 @@ int misc_deregister(struct miscdevice *misc) 
	list_del(&misc->list);

	device_destroy(misc_class, MKDEV(MISC_MAJOR, misc->minor));

	if (i < DYNAMIC_MINORS && i >= 0)

		misc_minors[i>>3] &= ~(1 << (i & 7));

		clear_bit(i, misc_minors);

	mutex_unlock(&misc_mtx);

	return 0;

}