From: Ming Lei <ming.lei@redhat.com>
Date: Thu, 28 Sep 2023 12:43:24 +0000 (+0800)
Subject: io_uring: retain top 8bits of uring_cmd flags for kernel internal use
X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=528ce6781726e022bc5dc84034360e6e8f1b89bd;p=linux.git

io_uring: retain top 8bits of uring_cmd flags for kernel internal use

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

Reviewed-by: Gabriel Krisman Bertazi <krisman@suse.de>
Reviewed-by: Anuj Gupta <anuj20.g@samsung.com>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
---

diff --git a/include/linux/io_uring.h b/include/linux/io_uring.h
index 106cdc55ff3bd..ae08d6f66e627 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 683ac2b747212..425f64eee44ed 100644
--- a/include/uapi/linux/io_uring.h
+++ b/include/uapi/linux/io_uring.h
@@ -249,13 +249,12 @@ 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 2dff4772bf14a..cb6bd99070459 100644
--- a/io_uring/io_uring.c
+++ b/io_uring/io_uring.c
@@ -4669,6 +4669,9 @@ 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 537795fddc87d..a0b0ec5473bfe 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) {