Subject: [RFC PATCH v4 1/4] liburing: add api to set napi busy poll settings

From: Stefan Roesch <[email-masked]>
Date: Fri, 18 Nov 2022 20:11:46 -0800

This adds two functions to manage the napi busy poll settings:
- io_uring_register_napi
- io_uring_unregister_napi

Signed-off-by: Stefan Roesch <[email-masked]>
---
 src/include/liburing.h          |  3 +++
 src/include/liburing/io_uring.h | 12 ++++++++++++
 src/liburing.map                |  6 ++++++
 src/register.c                  | 12 ++++++++++++
 4 files changed, 33 insertions(+)

diff --git a/src/include/liburing.h b/src/include/liburing.h
index 12a703f..98ffd73 100644
--- a/src/include/liburing.h
+++ b/src/include/liburing.h
@@ -235,6 +235,9 @@ int io_uring_register_sync_cancel(struct io_uring *ring,
 int io_uring_register_file_alloc_range(struct io_uring *ring,
 					unsigned off, unsigned len);
 
+int io_uring_register_napi(struct io_uring *ring, struct io_uring_napi *napi);
+int io_uring_unregister_napi(struct io_uring *ring, struct io_uring_napi *napi);
+
 int io_uring_get_events(struct io_uring *ring);
 int io_uring_submit_and_get_events(struct io_uring *ring);
 
diff --git a/src/include/liburing/io_uring.h b/src/include/liburing/io_uring.h
index a3e0920..25caee3 100644
--- a/src/include/liburing/io_uring.h
+++ b/src/include/liburing/io_uring.h
@@ -499,6 +499,10 @@ enum {
 	/* register a range of fixed file slots for automatic slot allocation */
 	IORING_REGISTER_FILE_ALLOC_RANGE	= 25,
 
+	/* set/clear busy poll settings */
+	IORING_REGISTER_NAPI			= 26,
+	IORING_UNREGISTER_NAPI			= 27,
+
 	/* this goes last */
 	IORING_REGISTER_LAST
 };
@@ -621,6 +625,14 @@ struct io_uring_buf_reg {
 	__u64	resv[3];
 };
 
+/* argument for IORING_(UN)REGISTER_NAPI */
+struct io_uring_napi {
+	__u32   busy_poll_to;
+	__u8    prefer_busy_poll;
+	__u8    pad[3];
+	__u64   resv;
+};
+
 /*
  * io_uring_restriction->opcode values
  */
diff --git a/src/liburing.map b/src/liburing.map
index 06c64f8..74036d3 100644
--- a/src/liburing.map
+++ b/src/liburing.map
@@ -67,3 +67,9 @@ LIBURING_2.3 {
 		io_uring_get_events;
 		io_uring_submit_and_get_events;
 } LIBURING_2.2;
+
+LIBURING_2.4 {
+	global:
+		io_uring_register_napi;
+		io_uring_unregister_napi;
+} LIBURING_2.3;
diff --git a/src/register.c b/src/register.c
index e849825..9b363e0 100644
--- a/src/register.c
+++ b/src/register.c
@@ -367,3 +367,15 @@ int io_uring_register_file_alloc_range(struct io_uring *ring,
 				       IORING_REGISTER_FILE_ALLOC_RANGE, &range,
 				       0);
 }
+
+int io_uring_register_napi(struct io_uring *ring, struct io_uring_napi *napi)
+{
+	return __sys_io_uring_register(ring->ring_fd,
+				IORING_REGISTER_NAPI, napi, 0);
+}
+
+int io_uring_unregister_napi(struct io_uring *ring, struct io_uring_napi *napi)
+{
+	return __sys_io_uring_register(ring->ring_fd,
+				IORING_REGISTER_NAPI, napi, 0);
+}
-- 
2.30.2