[PATCH RFC POC 50/50] Drivers: hv: mshv: stop putting descriptors back on failure

[Christian Brauner]

Rely on the fd exit path machinery.

Signed-off-by: Christian Brauner (Amutable) <brauner at kernel.org>
---
 drivers/hv/mshv_root_main.c | 27 +++++++--------------------
 drivers/hv/mshv_vtl_main.c  | 20 +++++---------------
 2 files changed, 12 insertions(+), 35 deletions(-)

diff --git a/drivers/hv/mshv_root_main.c b/drivers/hv/mshv_root_main.c
index cc2cfce2aefd..c95cee0bae85 100644
--- a/drivers/hv/mshv_root_main.c
+++ b/drivers/hv/mshv_root_main.c
@@ -1072,8 +1072,6 @@ mshv_partition_ioctl_create_vp(struct mshv_partition *partition,
 	struct mshv_vp *vp;
 	struct page *intercept_msg_page, *register_page, *ghcb_page;
 	struct hv_stats_page *stats_pages[2];
-	struct file *file;
-	int fd;
 	long ret;
 
 	if (copy_from_user(&args, arg, sizeof(args)))
@@ -1148,19 +1146,14 @@ mshv_partition_ioctl_create_vp(struct mshv_partition *partition,
 	if (ret)
 		goto put_partition;
 
-	fd = get_unused_fd_flags(O_RDWR | O_CLOEXEC);
-	if (fd < 0) {
-		ret = fd;
+	FD_PREPARE(fdf, O_RDWR | O_CLOEXEC,
+		   anon_inode_getfile("mshv_vp", &mshv_vp_fops, vp,
+				      O_RDWR | O_CLOEXEC));
+	if (IS_ERR(fdf)) {
+		ret = PTR_ERR(fdf);
 		goto remove_debugfs_vp;
 	}
 
-	file = anon_inode_getfile("mshv_vp", &mshv_vp_fops, vp,
-				  O_RDWR | O_CLOEXEC);
-	if (IS_ERR(file)) {
-		ret = PTR_ERR(file);
-		goto put_unused_vp_fd;
-	}
-
 	/* already exclusive with the partition mutex for all ioctls */
 	partition->pt_vp_count++;
 	/*
@@ -1171,17 +1164,11 @@ mshv_partition_ioctl_create_vp(struct mshv_partition *partition,
 	 */
 	smp_store_release(&partition->pt_vp_array[args.vp_index], vp);
 
-	/*
-	 * fd_install() is the userspace-visibility commit point.  Must be the
-	 * last operation that can fail or be observed.
-	 */
-	fd_install(fd, file);
-	ret = fd;
+	/* The syscall exit installs the file; nothing after this can fail. */
+	ret = fd_prepare_fd(fdf);
 
 	goto out;
 
-put_unused_vp_fd:
-	put_unused_fd(fd);
 remove_debugfs_vp:
 	mshv_debugfs_vp_remove(vp);
 put_partition:
diff --git a/drivers/hv/mshv_vtl_main.c b/drivers/hv/mshv_vtl_main.c
index 6e3c11c68171..f14203d76da1 100644
--- a/drivers/hv/mshv_vtl_main.c
+++ b/drivers/hv/mshv_vtl_main.c
@@ -114,29 +114,19 @@ static long
 mshv_ioctl_create_vtl(void __user *user_arg, struct device *module_dev)
 {
 	struct mshv_vtl *vtl;
-	struct file *file;
-	int fd;
 
 	vtl = kzalloc_obj(*vtl);
 	if (!vtl)
 		return -ENOMEM;
 
-	fd = get_unused_fd_flags(O_CLOEXEC);
-	if (fd < 0) {
-		kfree(vtl);
-		return fd;
-	}
-	file = anon_inode_getfile("mshv_vtl", &mshv_vtl_fops,
-				  vtl, O_RDWR);
-	if (IS_ERR(file)) {
-		put_unused_fd(fd);
+	FD_PREPARE(fdf, O_CLOEXEC,
+		   anon_inode_getfile("mshv_vtl", &mshv_vtl_fops, vtl, O_RDWR));
+	if (IS_ERR(fdf)) {
 		kfree(vtl);
-		return PTR_ERR(file);
+		return PTR_ERR(fdf);
 	}
 	vtl->module_dev = module_dev;
-	fd_install(fd, file);
-
-	return fd;
+	return fd_prepare_fd(fdf);
 }
 
 static long

-- 
2.53.0