Revision 7f59203abeaf18bf3497b308891f95a4489810ad authored by Josef Bacik on 27 January 2010, 02:09:00 UTC, committed by Chris Mason on 28 January 2010, 21:20:39 UTC
Hit this problem while testing RAID1 failure stuff. open_bdev_exclusive returns ERR_PTR(), not NULL. So change the return value properly. This is important if you accidently specify a device that doesn't exist when trying to add a new device to an array, you will panic the box dereferencing bdev. Signed-off-by: Josef Bacik <josef@redhat.com> Signed-off-by: Chris Mason <chris.mason@oracle.com>
1 parent f48b907
dec_and_lock.c
#include <linux/module.h>
#include <linux/spinlock.h>
#include <asm/atomic.h>
/*
* This is an implementation of the notion of "decrement a
* reference count, and return locked if it decremented to zero".
*
* NOTE NOTE NOTE! This is _not_ equivalent to
*
* if (atomic_dec_and_test(&atomic)) {
* spin_lock(&lock);
* return 1;
* }
* return 0;
*
* because the spin-lock and the decrement must be
* "atomic".
*/
int _atomic_dec_and_lock(atomic_t *atomic, spinlock_t *lock)
{
/* Subtract 1 from counter unless that drops it to 0 (ie. it was 1) */
if (atomic_add_unless(atomic, -1, 1))
return 0;
/* Otherwise do it the slow way */
spin_lock(lock);
if (atomic_dec_and_test(atomic))
return 1;
spin_unlock(lock);
return 0;
}
EXPORT_SYMBOL(_atomic_dec_and_lock);
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