linux-kernel - [PATCH V2 1/3] livepatch: remove 'struct completion finish' from klp

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Message-Id: <20211101003132.3336497-2-ming.lei@redhat.com>
Date:   Mon,  1 Nov 2021 08:31:30 +0800
From:   Ming Lei <ming.lei@...hat.com>
To:     Josh Poimboeuf <jpoimboe@...hat.com>,
        Jiri Kosina <jikos@...nel.org>,
        Miroslav Benes <mbenes@...e.cz>,
        Petr Mladek <pmladek@...e.com>, live-patching@...r.kernel.org
Cc:     linux-kernel@...r.kernel.org,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Luis Chamberlain <mcgrof@...nel.org>,
        Ming Lei <ming.lei@...hat.com>
Subject: [PATCH V2 1/3] livepatch: remove 'struct completion finish' from klp_patch

The completion finish is just for waiting release of the klp_patch
object, then releases module refcnt. We can simply drop the module
refcnt in the kobject release handler of klp_patch.

This way also helps to support allocating klp_patch from heap.

Signed-off-by: Ming Lei <ming.lei@...hat.com>
---
 include/linux/livepatch.h |  1 -
 kernel/livepatch/core.c   | 12 +++---------
 2 files changed, 3 insertions(+), 10 deletions(-)

diff --git a/include/linux/livepatch.h b/include/linux/livepatch.h
index 2614247a9781..9712818997c5 100644
--- a/include/linux/livepatch.h
+++ b/include/linux/livepatch.h
@@ -170,7 +170,6 @@ struct klp_patch {
 	bool enabled;
 	bool forced;
 	struct work_struct free_work;
-	struct completion finish;
 };
 
 #define klp_for_each_object_static(patch, obj) \
diff --git a/kernel/livepatch/core.c b/kernel/livepatch/core.c
index 335d988bd811..b967b4b0071b 100644
--- a/kernel/livepatch/core.c
+++ b/kernel/livepatch/core.c
@@ -551,10 +551,10 @@ static int klp_add_nops(struct klp_patch *patch)
 
 static void klp_kobj_release_patch(struct kobject *kobj)
 {
-	struct klp_patch *patch;
+	struct klp_patch *patch = container_of(kobj, struct klp_patch, kobj);
 
-	patch = container_of(kobj, struct klp_patch, kobj);
-	complete(&patch->finish);
+	if (!patch->forced)
+		module_put(patch->mod);
 }
 
 static struct kobj_type klp_ktype_patch = {
@@ -678,11 +678,6 @@ static void klp_free_patch_finish(struct klp_patch *patch)
 	 * cannot get enabled again.
 	 */
 	kobject_put(&patch->kobj);
-	wait_for_completion(&patch->finish);
-
-	/* Put the module after the last access to struct klp_patch. */
-	if (!patch->forced)
-		module_put(patch->mod);
 }
 
 /*
@@ -876,7 +871,6 @@ static int klp_init_patch_early(struct klp_patch *patch)
 	patch->enabled = false;
 	patch->forced = false;
 	INIT_WORK(&patch->free_work, klp_free_patch_work_fn);
-	init_completion(&patch->finish);
 
 	klp_for_each_object_static(patch, obj) {
 		if (!obj->funcs)
-- 
2.31.1