linux-kernel - Re: livepatch: separate enabled and patched states

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Date:	Sun, 10 Apr 2016 23:31:28 -0400
From:	Jessica Yu <jeyu@...hat.com>
To:	Josh Poimboeuf <jpoimboe@...hat.com>
Cc:	Jiri Kosina <jikos@...nel.org>, Miroslav Benes <mbenes@...e.cz>,
	linux-kernel@...r.kernel.org, live-patching@...r.kernel.org,
	Vojtech Pavlik <vojtech@...e.com>
Subject: Re: livepatch: separate enabled and patched states

+++ Josh Poimboeuf [25/03/16 14:34 -0500]:
>Once we have a consistency model, patches and their objects will be
>enabled and disabled at different times.  For example, when a patch is
>disabled, its loaded objects' funcs can remain registered with ftrace
>indefinitely until the unpatching operation is complete and they're no
>longer in use.
>
>It's less confusing if we give them different names: patches can be
>enabled or disabled; objects (and their funcs) can be patched or
>unpatched:
>
>- Enabled means that a patch is logically enabled (but not necessarily
>  fully applied).
>
>- Patched means that an object's funcs are registered with ftrace and
>  added to the klp_ops func stack.
>
>Also, since these states are binary, represent them with booleans
>instead of ints.
>
>Signed-off-by: Josh Poimboeuf <jpoimboe@...hat.com>
>---
> include/linux/livepatch.h | 17 ++++-------
> kernel/livepatch/core.c   | 72 +++++++++++++++++++++++------------------------
> 2 files changed, 42 insertions(+), 47 deletions(-)
>
>diff --git a/include/linux/livepatch.h b/include/linux/livepatch.h
>index bd830d5..6d45dc7 100644
>--- a/include/linux/livepatch.h
>+++ b/include/linux/livepatch.h
>@@ -28,11 +28,6 @@
>
> #include <asm/livepatch.h>
>
>-enum klp_state {
>-	KLP_DISABLED,
>-	KLP_ENABLED
>-};
>-
> /**
>  * struct klp_func - function structure for live patching
>  * @old_name:	name of the function to be patched
>@@ -41,8 +36,8 @@ enum klp_state {
>  *		can be found (optional)
>  * @old_addr:	the address of the function being patched
>  * @kobj:	kobject for sysfs resources
>- * @state:	tracks function-level patch application state
>  * @stack_node:	list node for klp_ops func_stack list
>+ * @patched:	the func has been added to the klp_ops list
>  */
> struct klp_func {
> 	/* external */
>@@ -60,8 +55,8 @@ struct klp_func {
> 	/* internal */
> 	unsigned long old_addr;
> 	struct kobject kobj;
>-	enum klp_state state;
> 	struct list_head stack_node;
>+	bool patched;
> };
>
> /**
>@@ -90,7 +85,7 @@ struct klp_reloc {
>  * @kobj:	kobject for sysfs resources
>  * @mod:	kernel module associated with the patched object
>  * 		(NULL for vmlinux)
>- * @state:	tracks object-level patch application state
>+ * @patched:	the object's funcs have been add to the klp_ops list

s/add/added :)