kernel/printk/printk_ringbuffer.c

70  * The descriptor ring has a @tail_id that contains the ID of the oldest
77  * @tail_id is advanced, followed by advancing @head_id. And finally the
81  * The @tail_id can only be advanced if the new @tail_id would be in the
772 			   unsigned long tail_id)
778 	d_state = desc_read(desc_ring, tail_id, &desc, NULL, NULL);
788 		    DESC_ID_PREV_WRAP(desc_ring, tail_id)) {
803 		desc_make_reusable(desc_ring, tail_id);
820 	 * Check the next descriptor after @tail_id before pushing the tail
828 	d_state = desc_read(desc_ring, DESC_ID(tail_id + 1), &desc,
839 		atomic_long_cmpxchg(&desc_ring->tail_id, tail_id,
840 				    DESC_ID(tail_id + 1)); /* LMM(desc_push_tail:B) */
844 		 * reloading @tail_id in order to see a new tail ID in the
867 		 * Re-check the tail ID. The descriptor following @tail_id is
871 		if (atomic_long_read(&desc_ring->tail_id) == tail_id) /* LMM(desc_push_tail:D) */
918 		if (id_prev_wrap == atomic_long_read(&desc_ring->tail_id
1955 		id = atomic_long_read(&rb->desc_ring.tail_id); /* LMM(prb_first_seq:A) */
1968 		 * reloading @tail_id in order to see a new tail in the case
2316 	atomic_long_set(&rb->desc_ring.tail_id, DESC0_ID(descbits));