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Fix race in rwlock implementation which can occur when

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your task is rescheduled to a different cpu after you've
taken the lock but before calling RW_LOCK_HELD is called.
We need the spinlock to ensure there is a wmb() there.


git-svn-id: https://outreach.scidac.gov/svn/spl/trunk@68 7e1ea52c-4ff2-0310-8f11-9dd32ca42a1c
This commit is contained in:
behlendo
2008-04-07 23:54:34 +00:00
parent 728b9dd800
commit 79f92663e3
2 changed files with 11 additions and 2 deletions
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modules/spl/spl-rwlock.c
+7 -2
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@@ -29,16 +29,21 @@ EXPORT_SYMBOL(__rw_write_held);
int
__rw_lock_held(krwlock_t *rwlp)
{
int rc = 0;
BUG_ON(rwlp->rw_magic != RW_MAGIC);
spin_lock_irq(&(rwlp->rw_sem.wait_lock));
#ifdef CONFIG_RWSEM_GENERIC_SPINLOCK
if (rwlp->rw_sem.activity != 0) {
#else
if (rwlp->rw_sem.count != 0) {
#endif
return 1;
rc = 1;
}
return 0;
spin_unlock_irq(&(rwlp->rw_sem.wait_lock));
return rc;
}
EXPORT_SYMBOL(__rw_lock_held);