adulau/aha
1
0
Fork 0
mirror of https://github.com/adulau/aha.git synced 2024-12-27 19:26:25 +00:00
Code Issues Projects Releases Packages Wiki Activity

drivers/char/misc.c: use bitmap/bitops functions for dynamic minor number allocation

Browse source 
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>
This commit is contained in:
Thadeu Lima de Souza Cascardo 2009-12-14 18:00:31 -08:00 committed by Linus Torvalds
parent 4ae717da8d
commit 1f2f38d89d
1 changed files with 9 additions and 13 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

22
drivers/char/misc.c
View file

@ -60,7 +60,7 @@ static DEFINE_MUTEX(misc_mtx);
* Assigned numbers, used for dynamic minors * Assigned numbers, used for dynamic minors
*/ */
#define DYNAMIC_MINORS 64 /* like dynamic majors */ #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 #ifdef CONFIG_PROC_FS
static void *misc_seq_start(struct seq_file *seq, loff_t *pos) 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) { if (misc->minor == MISC_DYNAMIC_MINOR) {
int i = DYNAMIC_MINORS; int i = find_first_zero_bit(misc_minors, DYNAMIC_MINORS);
while (--i >= 0) if (i >= DYNAMIC_MINORS) {
if ( (misc_minors[i>>3] & (1 << (i&7))) == 0)
break;
if (i<0) {
mutex_unlock(&misc_mtx); mutex_unlock(&misc_mtx);
return -EBUSY; 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); dev = MKDEV(MISC_MAJOR, misc->minor);
misc->this_device = device_create(misc_class, misc->parent, dev, misc->this_device = device_create(misc_class, misc->parent, dev,
misc, "%s", misc->name); misc, "%s", misc->name);
if (IS_ERR(misc->this_device)) { if (IS_ERR(misc->this_device)) {
int i = misc->minor; int i = DYNAMIC_MINORS - misc->minor - 1;
if (i < DYNAMIC_MINORS && i >= 0) if (i < DYNAMIC_MINORS && i >= 0)
misc_minors[i>>3] &= ~(1 << (i & 7)); clear_bit(i, misc_minors);
err = PTR_ERR(misc->this_device); err = PTR_ERR(misc->this_device);
goto out; goto out;
} }
@ -243,7 +239,7 @@ int misc_register(struct miscdevice * misc)
int misc_deregister(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)) if (list_empty(&misc->list))
return -EINVAL; return -EINVAL;
@ -252,7 +248,7 @@ int misc_deregister(struct miscdevice *misc)
list_del(&misc->list); list_del(&misc->list);
device_destroy(misc_class, MKDEV(MISC_MAJOR, misc->minor)); device_destroy(misc_class, MKDEV(MISC_MAJOR, misc->minor));
if (i < DYNAMIC_MINORS && i >= 0) if (i < DYNAMIC_MINORS && i >= 0)
misc_minors[i>>3] &= ~(1 << (i & 7)); clear_bit(i, misc_minors);
mutex_unlock(&misc_mtx); mutex_unlock(&misc_mtx);
return 0; return 0;
} }