Commit 2fb29209 authored by Peter Zijlstra's avatar Peter Zijlstra
Browse files

futex: Pull futex_hash() out of futex_q_lock() 



Getting the hash bucket and queuing it are two distinct actions. In
light of wanting to add a put hash bucket function later, untangle
them.

Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: default avatarSebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20250416162921.513656-5-bigeasy@linutronix.de
parent 93f1b6d7

kernel/futex/core.c

+1 −6
Original line number Diff line number Diff line
@@ -502,13 +502,9 @@ void __futex_unqueue(struct futex_q *q) 
}



/* The key must be already stored in q->key. */

struct futex_hash_bucket *futex_q_lock(struct futex_q *q)

void futex_q_lock(struct futex_q *q, struct futex_hash_bucket *hb)

	__acquires(&hb->lock)

{

	struct futex_hash_bucket *hb;



	hb = futex_hash(&q->key);



	/*

	 * Increment the counter before taking the lock so that

	 * a potential waker won't miss a to-be-slept task that is
@@ -522,7 +518,6 @@ struct futex_hash_bucket *futex_q_lock(struct futex_q *q) 
	q->lock_ptr = &hb->lock;



	spin_lock(&hb->lock);

	return hb;

}



void futex_q_unlock(struct futex_hash_bucket *hb)

kernel/futex/futex.h

+1 −1
Original line number Diff line number Diff line
@@ -354,7 +354,7 @@ static inline int futex_hb_waiters_pending(struct futex_hash_bucket *hb) 
#endif

}



extern struct futex_hash_bucket *futex_q_lock(struct futex_q *q);

extern void futex_q_lock(struct futex_q *q, struct futex_hash_bucket *hb);

extern void futex_q_unlock(struct futex_hash_bucket *hb);

kernel/futex/pi.c

+2 −1
Original line number Diff line number Diff line
@@ -939,7 +939,8 @@ int futex_lock_pi(u32 __user *uaddr, unsigned int flags, ktime_t *time, int tryl 
		goto out;



retry_private:

	hb = futex_q_lock(&q);

	hb = futex_hash(&q.key);

	futex_q_lock(&q, hb);



	ret = futex_lock_pi_atomic(uaddr, hb, &q.key, &q.pi_state, current,

				   &exiting, 0);

kernel/futex/waitwake.c

+4 −2
Original line number Diff line number Diff line
@@ -441,7 +441,8 @@ int futex_wait_multiple_setup(struct futex_vector *vs, int count, int *woken) 
		struct futex_q *q = &vs[i].q;

		u32 val = vs[i].w.val;



		hb = futex_q_lock(q);

		hb = futex_hash(&q->key);

		futex_q_lock(q, hb);

		ret = futex_get_value_locked(&uval, uaddr);



		if (!ret && uval == val) {
@@ -611,7 +612,8 @@ int futex_wait_setup(u32 __user *uaddr, u32 val, unsigned int flags, 
		return ret;



retry_private:

	hb = futex_q_lock(q);

	hb = futex_hash(&q->key);

	futex_q_lock(q, hb);



	ret = futex_get_value_locked(&uval, uaddr);