linux-kernel - [PATCH v2 1/2] livepatch: Add comment to clarify klp_add

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Message-Id: <20250223062046.2943-2-laoar.shao@gmail.com>
Date: Sun, 23 Feb 2025 14:20:45 +0800
From: Yafang Shao <laoar.shao@...il.com>
To: jpoimboe@...nel.org,
	jikos@...nel.org,
	mbenes@...e.cz,
	pmladek@...e.com,
	joe.lawrence@...hat.com
Cc: live-patching@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	Yafang Shao <laoar.shao@...il.com>
Subject: [PATCH v2 1/2] livepatch: Add comment to clarify klp_add_nops()

Add detailed comments to clarify the purpose of klp_add_nops() function.
These comments are based on Petr's explanation[0].

Link: https://lore.kernel.org/all/Z6XUA7D0eU_YDMVp@pathway.suse.cz/ [0]
Suggested-by: Petr Mladek <pmladek@...e.com>
Suggested-by: Josh Poimboeuf <jpoimboe@...nel.org>
Signed-off-by: Yafang Shao <laoar.shao@...il.com>
---
 kernel/livepatch/core.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/kernel/livepatch/core.c b/kernel/livepatch/core.c
index 0cd39954d5a1..4a0fb7978d0d 100644
--- a/kernel/livepatch/core.c
+++ b/kernel/livepatch/core.c
@@ -601,9 +601,12 @@ static int klp_add_object_nops(struct klp_patch *patch,
 }
 
 /*
- * Add 'nop' functions which simply return to the caller to run
- * the original function. The 'nop' functions are added to a
- * patch to facilitate a 'replace' mode.
+ * Add 'nop' functions which simply return to the caller to run the
+ * original function.
+ *
+ * They are added only when the atomic replace mode is used and only for
+ * functions which are currently livepatched but are no longer included
+ * in the new livepatch.
  */
 static int klp_add_nops(struct klp_patch *patch)
 {
-- 
2.43.5