https://bugs.gentoo.org/917000
https://github.com/dracutdevs/dracut/pull/2494

From b88d0bab791bdc4ca75d13802f0391caf537650d Mon Sep 17 00:00:00 2001
From: Andrew Ammerlaan <andrewammerlaan@gentoo.org>
Date: Sun, 20 Aug 2023 11:47:22 +0200
Subject: [PATCH] fix(resume): include in hostonly mode if resume= on cmdline

The grep introduced in commit e3a7112bef794e2f2dd741ec2c74fa9cb9117651
does not work as intended. The resume module is always excluded in hostonly
mode.

Made this a bit more explicit with if/else so it is more clear what is going
on. The in-line ||/&& makes the line really long and makes it more difficult
to understand what is going on.

Bug: https://github.com/dracutdevs/dracut/issues/924
Signed-off-by: Andrew Ammerlaan <andrewammerlaan@gentoo.org>
---
 modules.d/95resume/module-setup.sh | 32 +++++++++++++++++++++++-------
 1 file changed, 25 insertions(+), 7 deletions(-)

diff --git a/modules.d/95resume/module-setup.sh b/modules.d/95resume/module-setup.sh
index d255103366..2d48043827 100755
--- a/modules.d/95resume/module-setup.sh
+++ b/modules.d/95resume/module-setup.sh
@@ -10,13 +10,31 @@ check() {
         return 1
     }
 
-    # Only support resume if hibernation is currently on
-    # and no swap is mounted on a net device
-    [[ $hostonly ]] || [[ $mount_needs ]] && {
-        swap_on_netdevice || [[ -f /sys/power/resume && "$(< /sys/power/resume)" == "0:0" ]] || grep -rq '^\|[[:space:]]resume=' /proc/cmdline /etc/cmdline /etc/cmdline.d /etc/kernel/cmdline /usr/lib/kernel/cmdline 2> /dev/null && return 255
-    }
-
-    return 0
+    # If hostonly check if we want to include the resume module
+    if [[ $hostonly ]] || [[ $mount_needs ]]; then
+        # Resuming won't work if swap is on a netdevice
+        swap_on_netdevice && return 255
+        if grep -rq 'resume=' /proc/cmdline /etc/cmdline /etc/cmdline.d /etc/kernel/cmdline /usr/lib/kernel/cmdline 2> /dev/null; then
+            # hibernation support requested on kernel command line
+            return 0
+        else
+            # resume= not set on kernel command line
+            if [[ -f /sys/power/resume ]]; then
+                if [[ "$(< /sys/power/resume)" == "0:0" ]]; then
+                    # hibernation supported by the kernel, but not enabled
+                    return 255
+                else
+                    # hibernation supported by the kernel and enabled
+                    return 0
+                fi
+            else
+                # resume file doesn't exist, hibernation not supported by kernel
+                return 255
+            fi
+        fi
+    else
+        return 0
+    fi
 }
 
 # called by dracut