[RFC 13/16] io_uring: refactor rings_size()

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

Refactor rings_size() to facilitate further changes. Move entries checks
to the beginning, which localises offset calculation. And instead of
special casing IORING_SETUP_NO_SQARRAY, reverse the check and just
continue offset calculation. This way it assign cq_comp_size only once
at the end.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
---
 io_uring/io_uring.c | 31 +++++++++++++++----------------
 1 file changed, 15 insertions(+), 16 deletions(-)

diff --git a/io_uring/io_uring.c b/io_uring/io_uring.c
index 4f38a0b587fd..ff52d9f110ce 100644
--- a/io_uring/io_uring.c
+++ b/io_uring/io_uring.c
@@ -2761,6 +2761,15 @@ int rings_size(unsigned int flags, unsigned int sq_entries,
 {
 	size_t cqe_size, off, sqe_size;
 
+	if (flags & IORING_SETUP_CQE_MIXED) {
+		if (cq_entries < 2)
+			return -EOVERFLOW;
+	}
+	if (flags & IORING_SETUP_SQE_MIXED) {
+		if (sq_entries < 2)
+			return -EOVERFLOW;
+	}
+
 	dims->sq_array_offset = SIZE_MAX;
 
 	sqe_size = sizeof(struct io_uring_sqe);
@@ -2786,29 +2795,19 @@ int rings_size(unsigned int flags, unsigned int sq_entries,
 	if (off == SIZE_MAX)
 		return -EOVERFLOW;
 
-	if (flags & IORING_SETUP_CQE_MIXED) {
-		if (cq_entries < 2)
-			return -EOVERFLOW;
-	}
-	if (flags & IORING_SETUP_SQE_MIXED) {
-		if (sq_entries < 2)
-			return -EOVERFLOW;
-	}
-
 #ifdef CONFIG_SMP
 	off = ALIGN(off, SMP_CACHE_BYTES);
 	if (off == 0)
 		return -EOVERFLOW;
 #endif
 
-	if (flags & IORING_SETUP_NO_SQARRAY) {
-		dims->cq_comp_size = off;
-		return 0;
-	}
+	if (!(flags & IORING_SETUP_NO_SQARRAY)) {
+		dims->sq_array_offset = off;
 
-	dims->sq_array_offset = off;
-	if (check_add_overflow(off, dims->sq_array_size, &off))
-		return -EOVERFLOW;
+		off = size_add(off, dims->sq_array_size);
+		if (off == SIZE_MAX)
+			return -EOVERFLOW;
+	}
 
 	dims->cq_comp_size = off;
 	return 0;
-- 
2.49.0