[PATCH review-only 03/17] io_uring/zcrx: add RQ iterator

[Pavel Begunkov <asml.silence@gmail.com>]

Add a iterator structure and helper functions for the refill queue
processing to avoid polluting io_zcrx_ring_refill() with extra state
and logic once it's extended in following patches.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
---
 io_uring/zcrx.c | 32 ++++++++++++++++++++++++++------
 1 file changed, 26 insertions(+), 6 deletions(-)

diff --git a/io_uring/zcrx.c b/io_uring/zcrx.c
index c4a9a663eba4..45b178afbbc3 100644
--- a/io_uring/zcrx.c
+++ b/io_uring/zcrx.c
@@ -1088,6 +1088,10 @@ void io_unregister_zcrx(struct io_ring_ctx *ctx)
 	xa_destroy(&ctx->zcrx_ctxs);
 }
 
+struct zcrx_rq_iter {
+	int rqes_left;
+};
+
 static inline u32 zcrx_rq_entries(struct zcrx_rq *rq)
 {
 	u32 entries;
@@ -1103,6 +1107,24 @@ static struct io_uring_zcrx_rqe *zcrx_next_rqe(struct zcrx_rq *rq, unsigned mask
 	return &rq->rqes[idx];
 }
 
+static inline void zcrx_rq_iter_init(struct zcrx_rq_iter *it,
+				     struct zcrx_rq *rq)
+{
+	it->rqes_left = min_t(unsigned, zcrx_rq_entries(rq), ZCRX_REFILL_CAP);
+}
+
+static inline bool zcrx_rq_iter_next(struct zcrx_rq_iter *it,
+				     struct zcrx_rq *rq,
+				     struct io_uring_zcrx_rqe **rqe)
+{
+	it->rqes_left--;
+	if (unlikely(it->rqes_left < 0))
+		return false;
+
+	*rqe = zcrx_next_rqe(rq, rq->nr_entries - 1);
+	return true;
+}
+
 static inline bool io_parse_rqe(struct io_uring_zcrx_rqe *rqe,
 				struct io_zcrx_ifq *ifq,
 				struct net_iov **ret_niov)
@@ -1131,17 +1153,15 @@ static unsigned io_zcrx_ring_refill(struct page_pool *pp,
 				    netmem_ref *netmems, unsigned to_alloc)
 {
 	struct zcrx_rq *rq = &ifq->rq;
-	unsigned int mask = rq->nr_entries - 1;
-	unsigned int rqes_left;
+	struct io_uring_zcrx_rqe *rqe;
+	struct zcrx_rq_iter it;
 	unsigned allocated = 0;
 
 	guard(spinlock_bh)(&rq->lock);
 
-	rqes_left = zcrx_rq_entries(rq);
-	rqes_left = min_t(unsigned, rqes_left, ZCRX_REFILL_CAP);
+	zcrx_rq_iter_init(&it, rq);
 
-	for (; rqes_left; rqes_left--) {
-		struct io_uring_zcrx_rqe *rqe = zcrx_next_rqe(rq, mask);
+	while (zcrx_rq_iter_next(&it, rq, &rqe)) {
 		struct net_iov *niov;
 		netmem_ref netmem;
 
-- 
2.54.0