Re: [PATCH 3/9] kernel/api: add debugfs interface for kernel API specifications

On Fri, Mar 13, 2026 at 04:32:23PM +0100, Greg Kroah-Hartman wrote:

On Fri, Mar 13, 2026 at 11:09:13AM -0400, Sasha Levin wrote:

quoted

Add a debugfs interface to expose kernel API specifications at runtime.
This allows tools and users to query the complete API specifications
through the debugfs filesystem.

The interface provides:
- /sys/kernel/debug/kapi/list - lists all available API specifications
- /sys/kernel/debug/kapi/specs/<name> - detailed info for each API

Each specification file includes:
- Function name, version, and descriptions
- Execution context requirements and flags
- Parameter details with types, flags, and constraints
- Return value specifications and success conditions
- Error codes with descriptions and conditions
- Locking requirements and constraints
- Signal handling specifications
- Examples, notes, and deprecation status

This enables runtime introspection of kernel APIs for documentation
tools, static analyzers, and debugging purposes.

Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 Documentation/dev-tools/kernel-api-spec.rst |  88 ++--

You are removing stuff from the file you created earlier in this patch
series, is that ok?

Sorry, just a rebasing artifact from shuffling patches around. I'll fix it.

quoted

--- /dev/null
+++ b/kernel/api/kapi_debugfs.c

@@ -0,0 +1,503 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Kernel API specification debugfs interface
+ *
+ * This provides a debugfs interface to expose kernel API specifications
+ * at runtime, allowing tools and users to query the complete API specs.
+ */

No copyright line?  :)

I'll add one.

And this is, a totally and crazy interface with debugfs, I love it!

Thanks :)

Two minor minor nits:

quoted

+static int __init kapi_debugfs_init(void)
+{
+	struct kernel_api_spec *spec;
+	struct dentry *spec_dir;
+
+	/* Create main directory */
+	kapi_debugfs_root = debugfs_create_dir("kapi", NULL);
+
+	/* Create list file */
+	debugfs_create_file("list", 0444, kapi_debugfs_root, NULL, &kapi_list_fops);
+
+	/* Create specs subdirectory */
+	spec_dir = debugfs_create_dir("specs", kapi_debugfs_root);
+
+	/* Create a file for each API spec */
+	for (spec = __start_kapi_specs; spec < __stop_kapi_specs; spec++) {
+		debugfs_create_file(spec->name, 0444, spec_dir, spec, &kapi_spec_fops);
+	}

No need for { }

ack

quoted

+
+	pr_info("Kernel API debugfs interface initialized\n");

When code is working properly, it should be quiet, no need for this as
initializing this can not fail.

ack

-- 
Thanks,
Sasha