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drivers/char/misc.c: clear allocation bit in minor bitmap when device register fails 

If there's a failure creating the device (because there's already one with
the same name, for example), the current implementation does not clear the
bit for the allocated minor and that number is lost for future
allocations.

Second, the test currently in misc_deregister is broken, since it does not
test for the 0 minor.

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 18:00:30 -08:00 committed by Linus Torvalds
parent 603c4ba96b
commit 4ae717da8d
1 changed files with 5 additions and 3 deletions
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8
drivers/char/misc.c
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@ -214,6 +214,9 @@ int misc_register(struct miscdevice * misc)
misc->this_device = device_create(misc_class, misc->parent, dev,
misc, "%s", misc->name);
if (IS_ERR(misc->this_device)) {
int i = misc->minor;
if (i < DYNAMIC_MINORS && i >= 0)
misc_minors[i>>3] &= ~(1 << (i & 7));
err = PTR_ERR(misc->this_device);
goto out;
}
@ -248,9 +251,8 @@ int misc_deregister(struct miscdevice *misc)
mutex_lock(&misc_mtx);
list_del(&misc->list);
device_destroy(misc_class, MKDEV(MISC_MAJOR, misc->minor));
if (i < DYNAMIC_MINORS && i>0) {
misc_minors[i>>3] &= ~(1 << (misc->minor & 7));
}
if (i < DYNAMIC_MINORS && i >= 0)
misc_minors[i>>3] &= ~(1 << (i & 7));
mutex_unlock(&misc_mtx);
return 0;
}