net/xdp/xsk_queue.h

18 	/* Hinder the adjacent cache prefetcher to prefetch the consumer
22 	u32 consumer ____cacheline_aligned_in_smp;
65  * consumer. For the Tx and fill rings, the kernel is the consumer and
68  * producer                         consumer
70  * if (LOAD ->consumer) {  (A)      LOAD.acq ->producer  (C)
72  *    STORE.rel ->producer (B)      STORE.rel ->consumer (D)
78  * the producer pointer. If this barrier was missing, the consumer
80  * before the producer has written the new data. The consumer would in
83  * (C) protects the consumer from speculatively loading the data before
89  * (A) is a control dependency that separates the load of ->consumer
90  * from the stores of $data. In case ->consumer indicates there is no
95  * store of the consumer pointer. If we did not have this memory
96  * barrier, the producer could observe the consumer pointer being set
97  * and overwrite the data with a new value before the consumer got the
98  * chance to read the old value. The consumer would thus miss reading
105  * producer                           consumer
113  * seen and read by the consumer.
115  * The consumer peeks into the ring to see if the producer has written
116  * any new entries. If so, the consumer can then read these entries
123 /* Functions that read and validate content from consumer rings. */
311 	smp_store_release(&q->ring->consumer, q->cached_cons); /* D, matchees A */  in __xskq_cons_release()
372 	return READ_ONCE(q->ring->producer) - READ_ONCE(q->ring->consumer);  in xskq_cons_present_entries()
390 	q->cached_cons = READ_ONCE(q->ring->consumer);  in xskq_prod_nb_free()
484 	return READ_ONCE(q->ring->consumer) == READ_ONCE(q->ring->producer);  in xskq_prod_is_empty()