From 81cee1350ff87537f8203d2db0e8ed2acdff7aef Mon Sep 17 00:00:00 2001
From: Konstantin Belousov <kib@FreeBSD.org>
Date: Fri, 19 Jan 2024 23:54:03 +0200
Subject: [PATCH] kcmp(2): implement for linuxkpi cdevs

(cherry picked from commit 41fb6dc3d4df632ffacf91b5631a718442d129d5)
---
 sys/compat/linuxkpi/common/src/linux_compat.c | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/sys/compat/linuxkpi/common/src/linux_compat.c b/sys/compat/linuxkpi/common/src/linux_compat.c
index b913ae602ab..69a17ea1a4a 100644
--- a/sys/compat/linuxkpi/common/src/linux_compat.c
+++ b/sys/compat/linuxkpi/common/src/linux_compat.c
@@ -1899,6 +1899,19 @@ linux_iminor(struct inode *inode)
 	return (minor(ldev->dev));
 }
 
+static int
+linux_file_kcmp(struct file *fp1, struct file *fp2, struct thread *td)
+{
+	struct linux_file *filp1, *filp2;
+
+	if (fp2->f_type != DTYPE_DEV)
+		return (3);
+
+	filp1 = fp1->f_data;
+	filp2 = fp2->f_data;
+	return (kcmp_cmp((uintptr_t)filp1->f_cdev, (uintptr_t)filp2->f_cdev));
+}
+
 struct fileops linuxfileops = {
 	.fo_read = linux_file_read,
 	.fo_write = linux_file_write,
@@ -1913,6 +1926,7 @@ struct fileops linuxfileops = {
 	.fo_chmod = invfo_chmod,
 	.fo_chown = invfo_chown,
 	.fo_sendfile = invfo_sendfile,
+	.fo_cmp = linux_file_kcmp,
 	.fo_flags = DFLAG_PASSABLE,
 };