From 7dff3d1cdfd1556d2137ddd8dd1916e0945ed240 Mon Sep 17 00:00:00 2001
From: Konstantin Belousov <kib@FreeBSD.org>
Date: Fri, 19 Jan 2024 23:36:50 +0200
Subject: [PATCH] kcmp(2): implement for devfs files

(cherry picked from commit 5c41d888de1aba0e82531fb6df4cc3b6989d37bd)
---
 sys/fs/devfs/devfs_vnops.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/sys/fs/devfs/devfs_vnops.c b/sys/fs/devfs/devfs_vnops.c
index 1df7d13be91..b8cf8c12d32 100644
--- a/sys/fs/devfs/devfs_vnops.c
+++ b/sys/fs/devfs/devfs_vnops.c
@@ -2012,6 +2012,14 @@ dev2udev(struct cdev *x)
 	return (cdev2priv(x)->cdp_inode);
 }
 
+static int
+devfs_cmp_f(struct file *fp1, struct file *fp2, struct thread *td)
+{
+	if (fp2->f_type != DTYPE_VNODE || fp2->f_ops != &devfs_ops_f)
+		return (3);
+	return (kcmp_cmp((uintptr_t)fp1->f_data, (uintptr_t)fp2->f_data));
+}
+
 static struct fileops devfs_ops_f = {
 	.fo_read =	devfs_read_f,
 	.fo_write =	devfs_write_f,
@@ -2027,6 +2035,7 @@ static struct fileops devfs_ops_f = {
 	.fo_seek =	vn_seek,
 	.fo_fill_kinfo = vn_fill_kinfo,
 	.fo_mmap =	devfs_mmap_f,
+	.fo_cmp =	devfs_cmp_f,
 	.fo_flags =	DFLAG_PASSABLE | DFLAG_SEEKABLE
 };