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futex: add helper to find the top prio waiter of a futex

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Improve legibility by wrapping finding the top waiter in a function.
This will be used by the follow-on patches for enabling requeue pi.

Signed-off-by: Darren Hart <dvhltc@us.ibm.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
This commit is contained in:
Darren Hart 2009-04-03 13:39:42 -07:00 committed by Thomas Gleixner
parent ca5f9524d6
commit 4b1c486b35
1 changed files with 19 additions and 0 deletions
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19
kernel/futex.c
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@ -276,6 +276,25 @@ void put_futex_key(int fshared, union futex_key *key)
drop_futex_key_refs(key); drop_futex_key_refs(key);
} }
/**
* futex_top_waiter() - Return the highest priority waiter on a futex
* @hb: the hash bucket the futex_q's reside in
* @key: the futex key (to distinguish it from other futex futex_q's)
*
* Must be called with the hb lock held.
*/
static struct futex_q *futex_top_waiter(struct futex_hash_bucket *hb,
union futex_key *key)
{
struct futex_q *this;
plist_for_each_entry(this, &hb->chain, list) {
if (match_futex(&this->key, key))
return this;
}
return NULL;
}
static u32 cmpxchg_futex_value_locked(u32 __user *uaddr, u32 uval, u32 newval) static u32 cmpxchg_futex_value_locked(u32 __user *uaddr, u32 uval, u32 newval)
{ {
u32 curval; u32 curval;