From 1f2f38d89d1eced2079189cd880eeacee378370a Mon Sep 17 00:00:00 2001
From: Thadeu Lima de Souza Cascardo <cascardo@holoscopio.com>
Date: Mon, 14 Dec 2009 18:00:31 -0800
Subject: [PATCH] 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: Thadeu 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: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
drivers/char/misc.c | 22 +++++++++-------------
1 file changed, 9 insertions(+), 13 deletions(-)
diff --git a/drivers/char/misc.c b/drivers/char/misc.c
index a3a02f6303c89..94a136e96c06c 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 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;
}
--
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