[zcrx-next 1/2] io_uring/zcrx: introduce io_parse_rqe()

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

Add a helper for verifying a rqe and extracting a niov out of it. It'll
be reused in following patches.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
---
 io_uring/zcrx.c | 36 +++++++++++++++++++++++-------------
 1 file changed, 23 insertions(+), 13 deletions(-)

diff --git a/io_uring/zcrx.c b/io_uring/zcrx.c
index b3cfe0c04920..d510ebc3d382 100644
--- a/io_uring/zcrx.c
+++ b/io_uring/zcrx.c
@@ -727,6 +727,28 @@ static struct io_uring_zcrx_rqe *io_zcrx_get_rqe(struct io_zcrx_ifq *ifq,
 	return &ifq->rqes[idx];
 }
 
+static inline bool io_parse_rqe(struct io_uring_zcrx_rqe *rqe,
+				struct io_zcrx_ifq *ifq,
+				struct net_iov **ret_niov)
+{
+	unsigned niov_idx, area_idx;
+	struct io_zcrx_area *area;
+
+	area_idx = rqe->off >> IORING_ZCRX_AREA_SHIFT;
+	niov_idx = (rqe->off & ~IORING_ZCRX_AREA_MASK) >> ifq->niov_shift;
+
+	if (unlikely(rqe->__pad || area_idx))
+		return false;
+	area = ifq->area;
+
+	if (unlikely(niov_idx >= area->nia.num_niovs))
+		return false;
+	niov_idx = array_index_nospec(niov_idx, area->nia.num_niovs);
+
+	*ret_niov = &area->nia.niovs[niov_idx];
+	return true;
+}
+
 static void io_zcrx_ring_refill(struct page_pool *pp,
 				struct io_zcrx_ifq *ifq)
 {
@@ -741,23 +763,11 @@ static void io_zcrx_ring_refill(struct page_pool *pp,
 
 	do {
 		struct io_uring_zcrx_rqe *rqe = io_zcrx_get_rqe(ifq, mask);
-		struct io_zcrx_area *area;
 		struct net_iov *niov;
-		unsigned niov_idx, area_idx;
 		netmem_ref netmem;
 
-		area_idx = rqe->off >> IORING_ZCRX_AREA_SHIFT;
-		niov_idx = (rqe->off & ~IORING_ZCRX_AREA_MASK) >> ifq->niov_shift;
-
-		if (unlikely(rqe->__pad || area_idx))
+		if (!io_parse_rqe(rqe, ifq, &niov))
 			continue;
-		area = ifq->area;
-
-		if (unlikely(niov_idx >= area->nia.num_niovs))
-			continue;
-		niov_idx = array_index_nospec(niov_idx, area->nia.num_niovs);
-
-		niov = &area->nia.niovs[niov_idx];
 		if (!io_zcrx_put_niov_uref(niov))
 			continue;
 
-- 
2.49.0