net/xdp/xsk_queue.h

17 	u32 producer ____cacheline_aligned_in_smp;
19 	 * pointer if the producer pointer is touched and vice versa.
59  * completion ring, the kernel is the producer and user space is the
61  * user space is the producer.
63  * producer                         consumer
65  * if (LOAD ->consumer) {  (A)      LOAD.acq ->producer  (C)
67  *    STORE.rel ->producer (B)      STORE.rel ->consumer (D)
73  * the producer pointer. If this barrier was missing, the consumer
74  * could observe the producer pointer being set and thus load the data
75  * before the producer has written the new data. The consumer would in
79  * the producer pointer actually has been read. If we do not have this
82  * between ->producer and data.
91  * barrier, the producer could observe the consumer pointer being set
100  * producer                           consumer
106  * The producer reserves one or more entries in the ring. It can then
110  * The consumer peeks into the ring to see if the producer has written
112  * and when it is done reading them release them back to the producer
113  * so that the producer can use these slots to fill in new entries.
287 	q->cached_prod = smp_load_acquire(&q->ring->producer);  /* C, matches B */  in __xskq_cons_peek()
342 	return READ_ONCE(q->ring->producer) - READ_ONCE(q->ring->consumer);  in xskq_cons_present_entries()
426 	smp_store_release(&q->ring->producer, idx); /* B, matches C */  in __xskq_prod_submit()
436 	__xskq_prod_submit(q, q->ring->producer + nb_entries);  in xskq_prod_submit_n()
442 	return READ_ONCE(q->ring->consumer) == READ_ONCE(q->ring->producer);  in xskq_prod_is_empty()