Subject: [PATCH v13 7/7] io_uring: add prefer busy poll to register and unregister napi api

From: Stefan Roesch <[email-masked]>
Date: Thu, 18 May 2023 14:17:51 -0700

This adds the napi prefer busy poll setting to the register and
unregister napi api. When napi is unregistered and arg is specified,
both napi settings: busy poll timeout and the prefer busy poll setting
are copied into the user structure.

Signed-off-by: Stefan Roesch <[email-masked]>
Acked-by: Jakub Kicinski <[email-masked]>
---
 include/uapi/linux/io_uring.h |  3 ++-
 io_uring/napi.c               | 10 +++++++---
 2 files changed, 9 insertions(+), 4 deletions(-)

diff --git a/include/uapi/linux/io_uring.h b/include/uapi/linux/io_uring.h
index 278c1a9de78c..16d17d6ab7f7 100644
--- a/include/uapi/linux/io_uring.h
+++ b/include/uapi/linux/io_uring.h
@@ -656,7 +656,8 @@ struct io_uring_buf_reg {
 /* argument for IORING_(UN)REGISTER_NAPI */
 struct io_uring_napi {
 	__u32	busy_poll_to;
-	__u32	pad;
+	__u8	prefer_busy_poll;
+	__u8	pad[3];
 	__u64	resv;
 };
 
diff --git a/io_uring/napi.c b/io_uring/napi.c
index 5d5330d66201..5790b2daf1d0 100644
--- a/io_uring/napi.c
+++ b/io_uring/napi.c
@@ -222,16 +222,18 @@ void io_napi_free(struct io_ring_ctx *ctx)
 int io_register_napi(struct io_ring_ctx *ctx, void __user *arg)
 {
 	const struct io_uring_napi curr = {
-		.busy_poll_to = ctx->napi_busy_poll_to,
+		.busy_poll_to 	  = ctx->napi_busy_poll_to,
+		.prefer_busy_poll = ctx->napi_prefer_busy_poll
 	};
 	struct io_uring_napi napi;
 
 	if (copy_from_user(&napi, arg, sizeof(napi)))
 		return -EFAULT;
-	if (napi.pad || napi.resv)
+	if (napi.pad[0] || napi.pad[1] || napi.pad[2] || napi.resv)
 		return -EINVAL;
 
 	WRITE_ONCE(ctx->napi_busy_poll_to, napi.busy_poll_to);
+	WRITE_ONCE(ctx->napi_prefer_busy_poll, !!napi.prefer_busy_poll);
 
 	if (copy_to_user(arg, &curr, sizeof(curr)))
 		return -EFAULT;
@@ -250,13 +252,15 @@ int io_register_napi(struct io_ring_ctx *ctx, void __user *arg)
 int io_unregister_napi(struct io_ring_ctx *ctx, void __user *arg)
 {
 	const struct io_uring_napi curr = {
-		.busy_poll_to = ctx->napi_busy_poll_to,
+		.busy_poll_to 	  = ctx->napi_busy_poll_to,
+		.prefer_busy_poll = ctx->napi_prefer_busy_poll
 	};
 
 	if (arg && copy_to_user(arg, &curr, sizeof(curr)))
 		return -EFAULT;
 
 	WRITE_ONCE(ctx->napi_busy_poll_to, 0);
+	WRITE_ONCE(ctx->napi_prefer_busy_poll, false);
 	return 0;
 }
 
-- 
2.39.1