From 1f2f38d89d1eced2079189cd880eeacee378370a Mon Sep 17 00:00:00 2001 From: Thadeu Lima de Souza Cascardo 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 Cc: "H. Peter Anvin" Cc: Alan Cox Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- 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 a3a02f6303c8..94a136e96c06 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; } -- GitLab