[PATCH v3 4/7] livepatch: Deprecate stack_order

[Yafang Shao <laoar.shao@gmail.com>]

stack_order is no longer needed for atomic-replace livepatches, as a
single function can only be modified by a unique replace_set.
To maintain backward compatibility, print a dummy value, as suggested by
sashiko-bot.

Signed-off-by: Yafang Shao <laoar.shao@gmail.com>
Cc: Wardenjohn <zhangwarden@gmail.com>
---
 .../ABI/removed/sysfs-kernel-livepatch        |  9 +++
 .../ABI/testing/sysfs-kernel-livepatch        |  9 ---
 kernel/livepatch/core.c                       | 20 +-----
 .../testing/selftests/livepatch/test-sysfs.sh | 69 -------------------
 4 files changed, 12 insertions(+), 95 deletions(-)
 create mode 100644 Documentation/ABI/removed/sysfs-kernel-livepatch

diff --git a/Documentation/ABI/removed/sysfs-kernel-livepatch b/Documentation/ABI/removed/sysfs-kernel-livepatch
new file mode 100644
index 000000000000..72c1ce0ea864
--- /dev/null
+++ b/Documentation/ABI/removed/sysfs-kernel-livepatch
@@ -0,0 +1,9 @@
+What:		/sys/kernel/livepatch/<patch>/stack_order
+Date:		Jan 2025
+KernelVersion:	6.14.0
+Description:
+		This attribute specifies the sequence in which live patch modules
+		are applied to the system. If multiple live patches modify the same
+		function, the implementation with the biggest 'stack_order' number
+		is used, unless a transition is currently in progress.
+
diff --git a/Documentation/ABI/testing/sysfs-kernel-livepatch b/Documentation/ABI/testing/sysfs-kernel-livepatch
index 6d75235a6a2e..9d356d8b8c75 100644
--- a/Documentation/ABI/testing/sysfs-kernel-livepatch
+++ b/Documentation/ABI/testing/sysfs-kernel-livepatch
@@ -54,15 +54,6 @@ Contact:	live-patching@vger.kernel.org
 Description:
 		An attribute to show the replace_set of this livepatch.
 
-What:		/sys/kernel/livepatch/<patch>/stack_order
-Date:		Jan 2025
-KernelVersion:	6.14.0
-Description:
-		This attribute specifies the sequence in which live patch modules
-		are applied to the system. If multiple live patches modify the same
-		function, the implementation with the biggest 'stack_order' number
-		is used, unless a transition is currently in progress.
-
 What:		/sys/kernel/livepatch/<patch>/<object>
 Date:		Nov 2014
 KernelVersion:	3.19.0
diff --git a/kernel/livepatch/core.c b/kernel/livepatch/core.c
index 361999e5ce3d..c73eccd2cd13 100644
--- a/kernel/livepatch/core.c
+++ b/kernel/livepatch/core.c
@@ -330,7 +330,7 @@ int klp_apply_section_relocs(struct module *pmod, Elf_Shdr *sechdrs,
  * /sys/kernel/livepatch/<patch>/transition
  * /sys/kernel/livepatch/<patch>/force
  * /sys/kernel/livepatch/<patch>/replace_set
- * /sys/kernel/livepatch/<patch>/stack_order
+ * /sys/kernel/livepatch/<patch>/stack_order <deprecated>
  * /sys/kernel/livepatch/<patch>/<object>
  * /sys/kernel/livepatch/<patch>/<object>/patched
  * /sys/kernel/livepatch/<patch>/<object>/<function,sympos>
@@ -436,25 +436,11 @@ static ssize_t replace_set_show(struct kobject *kobj,
 	return sysfs_emit(buf, "%u\n", patch->replace_set);
 }
 
+/* This interface is deprecated and will be removed in the next release */
 static ssize_t stack_order_show(struct kobject *kobj,
 				struct kobj_attribute *attr, char *buf)
 {
-	struct klp_patch *patch, *this_patch;
-	int stack_order = 0;
-
-	this_patch = container_of(kobj, struct klp_patch, kobj);
-
-	mutex_lock(&klp_mutex);
-
-	klp_for_each_patch(patch) {
-		stack_order++;
-		if (patch == this_patch)
-			break;
-	}
-
-	mutex_unlock(&klp_mutex);
-
-	return sysfs_emit(buf, "%d\n", stack_order);
+	return sysfs_emit(buf, "-1\n");
 }
 
 static struct kobj_attribute enabled_kobj_attr = __ATTR_RW(enabled);
diff --git a/tools/testing/selftests/livepatch/test-sysfs.sh b/tools/testing/selftests/livepatch/test-sysfs.sh
index 58fe1d96997c..0c31759f34f6 100755
--- a/tools/testing/selftests/livepatch/test-sysfs.sh
+++ b/tools/testing/selftests/livepatch/test-sysfs.sh
@@ -21,8 +21,6 @@ check_sysfs_rights "$MOD_LIVEPATCH" "enabled" "-rw-r--r--"
 check_sysfs_value  "$MOD_LIVEPATCH" "enabled" "1"
 check_sysfs_rights "$MOD_LIVEPATCH" "force" "--w-------"
 check_sysfs_rights "$MOD_LIVEPATCH" "replace" "-r--r--r--"
-check_sysfs_rights "$MOD_LIVEPATCH" "stack_order" "-r--r--r--"
-check_sysfs_value  "$MOD_LIVEPATCH" "stack_order" "1"
 check_sysfs_rights "$MOD_LIVEPATCH" "transition" "-r--r--r--"
 check_sysfs_value  "$MOD_LIVEPATCH" "transition" "0"
 check_sysfs_rights "$MOD_LIVEPATCH" "vmlinux/patched" "-r--r--r--"
@@ -135,71 +133,4 @@ livepatch: '$MOD_LIVEPATCH': completing unpatching transition
 livepatch: '$MOD_LIVEPATCH': unpatching complete
 % rmmod $MOD_LIVEPATCH"
 
-start_test "sysfs test stack_order value"
-
-load_lp $MOD_LIVEPATCH
-
-check_sysfs_value  "$MOD_LIVEPATCH" "stack_order" "1"
-
-load_lp $MOD_LIVEPATCH2
-
-check_sysfs_value  "$MOD_LIVEPATCH2" "stack_order" "2"
-
-load_lp $MOD_LIVEPATCH3
-
-check_sysfs_value  "$MOD_LIVEPATCH3" "stack_order" "3"
-
-disable_lp $MOD_LIVEPATCH2
-unload_lp $MOD_LIVEPATCH2
-
-check_sysfs_value  "$MOD_LIVEPATCH" "stack_order" "1"
-check_sysfs_value  "$MOD_LIVEPATCH3" "stack_order" "2"
-
-disable_lp $MOD_LIVEPATCH3
-unload_lp $MOD_LIVEPATCH3
-
-disable_lp $MOD_LIVEPATCH
-unload_lp $MOD_LIVEPATCH
-
-check_result "% insmod test_modules/$MOD_LIVEPATCH.ko
-livepatch: enabling patch '$MOD_LIVEPATCH'
-livepatch: '$MOD_LIVEPATCH': initializing patching transition
-livepatch: '$MOD_LIVEPATCH': starting patching transition
-livepatch: '$MOD_LIVEPATCH': completing patching transition
-livepatch: '$MOD_LIVEPATCH': patching complete
-% insmod test_modules/$MOD_LIVEPATCH2.ko
-livepatch: enabling patch '$MOD_LIVEPATCH2'
-livepatch: '$MOD_LIVEPATCH2': initializing patching transition
-$MOD_LIVEPATCH2: pre_patch_callback: vmlinux
-livepatch: '$MOD_LIVEPATCH2': starting patching transition
-livepatch: '$MOD_LIVEPATCH2': completing patching transition
-$MOD_LIVEPATCH2: post_patch_callback: vmlinux
-livepatch: '$MOD_LIVEPATCH2': patching complete
-% insmod test_modules/$MOD_LIVEPATCH3.ko
-livepatch: enabling patch '$MOD_LIVEPATCH3'
-livepatch: '$MOD_LIVEPATCH3': initializing patching transition
-livepatch: '$MOD_LIVEPATCH3': starting patching transition
-livepatch: '$MOD_LIVEPATCH3': completing patching transition
-livepatch: '$MOD_LIVEPATCH3': patching complete
-% echo 0 > $SYSFS_KLP_DIR/$MOD_LIVEPATCH2/enabled
-livepatch: '$MOD_LIVEPATCH2': initializing unpatching transition
-$MOD_LIVEPATCH2: pre_unpatch_callback: vmlinux
-livepatch: '$MOD_LIVEPATCH2': starting unpatching transition
-livepatch: '$MOD_LIVEPATCH2': completing unpatching transition
-$MOD_LIVEPATCH2: post_unpatch_callback: vmlinux
-livepatch: '$MOD_LIVEPATCH2': unpatching complete
-% rmmod $MOD_LIVEPATCH2
-% echo 0 > $SYSFS_KLP_DIR/$MOD_LIVEPATCH3/enabled
-livepatch: '$MOD_LIVEPATCH3': initializing unpatching transition
-livepatch: '$MOD_LIVEPATCH3': starting unpatching transition
-livepatch: '$MOD_LIVEPATCH3': completing unpatching transition
-livepatch: '$MOD_LIVEPATCH3': unpatching complete
-% rmmod $MOD_LIVEPATCH3
-% echo 0 > $SYSFS_KLP_DIR/$MOD_LIVEPATCH/enabled
-livepatch: '$MOD_LIVEPATCH': initializing unpatching transition
-livepatch: '$MOD_LIVEPATCH': starting unpatching transition
-livepatch: '$MOD_LIVEPATCH': completing unpatching transition
-livepatch: '$MOD_LIVEPATCH': unpatching complete
-% rmmod $MOD_LIVEPATCH"
-
 exit 0
-- 
2.52.0