[RFC 08/16] io_uring: pre-calculate scq offsets

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

Move ring size / offset calculations into io_prepare_config(). It
simplifies misconfiguration handling, keeps it local, allows to move
p->sq_off.array calculation closer to the rest of p->sq_off init.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
---
 io_uring/io_uring.c | 28 ++++++++++++++--------------
 io_uring/io_uring.h |  1 +
 2 files changed, 15 insertions(+), 14 deletions(-)

diff --git a/io_uring/io_uring.c b/io_uring/io_uring.c
index 8166ea9140f8..aeb9555bd258 100644
--- a/io_uring/io_uring.c
+++ b/io_uring/io_uring.c
@@ -3362,23 +3362,20 @@ bool io_is_uring_fops(struct file *file)
 }
 
 static __cold int io_allocate_scq_urings(struct io_ring_ctx *ctx,
-					 struct io_uring_params *p)
+					 struct io_ctx_config *config)
 {
+	struct io_uring_params *p = &config->p;
+	struct io_scq_dim *dims = &config->dims;
 	struct io_uring_region_desc rd;
 	struct io_rings *rings;
-	struct io_scq_dim dims;
 	int ret;
 
 	/* make sure these are sane, as we already accounted them */
 	ctx->sq_entries = p->sq_entries;
 	ctx->cq_entries = p->cq_entries;
 
-	ret = rings_size(ctx->flags, p->sq_entries, p->cq_entries, &dims);
-	if (ret)
-		return ret;
-
 	memset(&rd, 0, sizeof(rd));
-	rd.size = PAGE_ALIGN(dims.cq_comp_size);
+	rd.size = PAGE_ALIGN(dims->cq_comp_size);
 	if (ctx->flags & IORING_SETUP_NO_MMAP) {
 		rd.user_addr = p->cq_off.user_addr;
 		rd.flags |= IORING_MEM_REGION_TYPE_USER;
@@ -3387,12 +3384,11 @@ static __cold int io_allocate_scq_urings(struct io_ring_ctx *ctx,
 	if (ret)
 		return ret;
 	ctx->rings = rings = io_region_get_ptr(&ctx->ring_region);
-
 	if (!(ctx->flags & IORING_SETUP_NO_SQARRAY))
-		ctx->sq_array = (u32 *)((char *)rings + dims.sq_array_offset);
+		ctx->sq_array = (u32 *)((char *)rings + dims->sq_array_offset);
 
 	memset(&rd, 0, sizeof(rd));
-	rd.size = PAGE_ALIGN(dims.sq_size);
+	rd.size = PAGE_ALIGN(dims->sq_size);
 	if (ctx->flags & IORING_SETUP_NO_MMAP) {
 		rd.user_addr = p->sq_off.user_addr;
 		rd.flags |= IORING_MEM_REGION_TYPE_USER;
@@ -3569,6 +3565,13 @@ static int io_prepare_config(struct io_ctx_config *config)
 	if (ret)
 		return ret;
 
+	ret = rings_size(p->flags, p->sq_entries, p->cq_entries, &config->dims);
+	if (ret)
+		return ret;
+
+	if (!(p->flags & IORING_SETUP_NO_SQARRAY))
+		p->sq_off.array = config->dims.sq_array_offset;
+
 	return 0;
 }
 
@@ -3641,13 +3644,10 @@ static __cold int io_uring_create(struct io_ctx_config *config)
 	mmgrab(current->mm);
 	ctx->mm_account = current->mm;
 
-	ret = io_allocate_scq_urings(ctx, p);
+	ret = io_allocate_scq_urings(ctx, config);
 	if (ret)
 		goto err;
 
-	if (!(p->flags & IORING_SETUP_NO_SQARRAY))
-		p->sq_off.array = (char *)ctx->sq_array - (char *)ctx->rings;
-
 	ret = io_sq_offload_create(ctx, p);
 	if (ret)
 		goto err;
diff --git a/io_uring/io_uring.h b/io_uring/io_uring.h
index 29464be9733c..d1c2c70720f1 100644
--- a/io_uring/io_uring.h
+++ b/io_uring/io_uring.h
@@ -27,6 +27,7 @@ struct io_scq_dim {
 
 struct io_ctx_config {
 	struct io_uring_params p;
+	struct io_scq_dim dims;
 	struct io_uring_params __user *uptr;
 };
 
-- 
2.49.0