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Commit 4b1c486b authored by Darren Hart's avatar Darren Hart Committed by Thomas Gleixner
Browse files

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



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: default avatarDarren Hart <dvhltc@us.ibm.com>
Reviewed-by: default avatarThomas Gleixner <tglx@linutronix.de>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
parent ca5f9524

kernel/futex.c

+19 −0
Original line number Diff line number Diff line
@@ -276,6 +276,25 @@ void put_futex_key(int fshared, union futex_key *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)

{

	u32 curval;