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Subject[PATCH] char/misc.c: misc_register: Do not loop on misc_list unconditionally
If the minor number is assigned dynamically, there is no need to
search for misc->minor in misc_list, since misc->minor ==
MISC_DYNAMIC_MINOR.

Signed-off-by: Dae S. Kim <dae@velatum.com>
---
drivers/char/misc.c | 13 +++++++------
1 file changed, 7 insertions(+), 6 deletions(-)

diff --git a/drivers/char/misc.c b/drivers/char/misc.c
index 522136d..7b262b6 100644
--- a/drivers/char/misc.c
+++ b/drivers/char/misc.c
@@ -190,12 +190,6 @@ int misc_register(struct miscdevice * misc)
INIT_LIST_HEAD(&misc->list);

mutex_lock(&misc_mtx);
- list_for_each_entry(c, &misc_list, list) {
- if (c->minor == misc->minor) {
- mutex_unlock(&misc_mtx);
- return -EBUSY;
- }
- }

if (misc->minor == MISC_DYNAMIC_MINOR) {
int i = find_first_zero_bit(misc_minors, DYNAMIC_MINORS);
@@ -205,6 +199,13 @@ int misc_register(struct miscdevice * misc)
}
misc->minor = DYNAMIC_MINORS - i - 1;
set_bit(i, misc_minors);
+ } else {
+ list_for_each_entry(c, &misc_list, list) {
+ if (c->minor == misc->minor) {
+ mutex_unlock(&misc_mtx);
+ return -EBUSY;
+ }
+ }
}

dev = MKDEV(MISC_MAJOR, misc->minor);
--
1.7.9.5


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