[PATCH V4 1/2] io_uring: retain top 8bits of uring_cmd flags for kernel internal use

Ming Lei
2023-09-23T02:52:00Z

Retain top 8bits of uring_cmd flags for kernel internal use, so that we
can move IORING_URING_CMD_POLLED out of uapi header.

Signed-off-by: Ming Lei <ming.lei@redhat.com>
---
include/linux/io_uring.h | 3 +++
include/uapi/linux/io_uring.h | 5 ++---
io_uring/io_uring.c | 3 +++
io_uring/uring_cmd.c | 2 +-
4 files changed, 9 insertions(+), 4 deletions(-)

diff --git a/include/linux/io_uring.h b/include/linux/io_uring.h
index 106cdc55ff3b..ae08d6f66e62 100644
--- a/include/linux/io_uring.h
+++ b/include/linux/io_uring.h
@@ -22,6 +22,9 @@ enum io_uring_cmd_flags {
IO_URING_F_IOPOLL = (1 << 10),
};

+/* only top 8 bits of sqe->uring_cmd_flags for kernel internal use */
+#define IORING_URING_CMD_POLLED (1U << 31)
+
struct io_uring_cmd {
struct file *file;
const struct io_uring_sqe *sqe;
diff --git a/include/uapi/linux/io_uring.h b/include/uapi/linux/io_uring.h
index 8e61f8b7c2ce..de77ad08b123 100644
--- a/include/uapi/linux/io_uring.h
+++ b/include/uapi/linux/io_uring.h
@@ -246,13 +246,12 @@ enum io_uring_op {
};

/*
- * sqe->uring_cmd_flags
+ * sqe->uring_cmd_flags top 8bits aren't available for userspace
* IORING_URING_CMD_FIXED use registered buffer; pass this flag
* along with setting sqe->buf_index.
- * IORING_URING_CMD_POLLED driver use only
*/
#define IORING_URING_CMD_FIXED (1U << 0)
-#define IORING_URING_CMD_POLLED (1U << 31)
+#define IORING_URING_CMD_MASK IORING_URING_CMD_FIXED

/*
diff --git a/io_uring/io_uring.c b/io_uring/io_uring.c
index 783ed0fff71b..9aedb7202403 100644
--- a/io_uring/io_uring.c
+++ b/io_uring/io_uring.c
@@ -4666,6 +4666,9 @@ static int __init io_uring_init(void)

BUILD_BUG_ON(sizeof(atomic_t) != sizeof(u32));

+ /* top 8bits are for internal use */
+ BUILD_BUG_ON((IORING_URING_CMD_MASK & 0xff000000) != 0);
+
io_uring_optable_init();

/*
diff --git a/io_uring/uring_cmd.c b/io_uring/uring_cmd.c
index 537795fddc87..a0b0ec5473bf 100644
--- a/io_uring/uring_cmd.c
+++ b/io_uring/uring_cmd.c
@@ -91,7 +91,7 @@ int io_uring_cmd_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
return -EINVAL;

ioucmd->flags = READ_ONCE(sqe->uring_cmd_flags);
- if (ioucmd->flags & ~IORING_URING_CMD_FIXED)
+ if (ioucmd->flags & ~IORING_URING_CMD_MASK)
return -EINVAL;

if (ioucmd->flags & IORING_URING_CMD_FIXED) {
--
2.41.0