linux-kernel - [PATCH] livepatch: Move error print out of lock protection in klp_enable

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Date:   Thu, 1 Sep 2022 10:27:06 +0800
From:   Zhen Lei <thunder.leizhen@...wei.com>
To:     Josh Poimboeuf <jpoimboe@...nel.org>,
        Jiri Kosina <jikos@...nel.org>,
        Miroslav Benes <mbenes@...e.cz>,
        Petr Mladek <pmladek@...e.com>,
        Joe Lawrence <joe.lawrence@...hat.com>,
        <live-patching@...r.kernel.org>, <linux-kernel@...r.kernel.org>
CC:     Zhen Lei <thunder.leizhen@...wei.com>
Subject: [PATCH] livepatch: Move error print out of lock protection in klp_enable_patch()

The patch->mod is not a protected object of mutex_lock(&klp_mutex). Since
it's in the error handling branch, it might not be helpful to reduce lock
conflicts, but it can reduce some code size.

Before:
   text    data     bss     dec     hex filename
  10330     464       8   10802    2a32 kernel/livepatch/core.o

After:
   text    data     bss     dec     hex filename
  10307     464       8   10779    2a1b kernel/livepatch/core.o

Signed-off-by: Zhen Lei <thunder.leizhen@...wei.com>
---
 kernel/livepatch/core.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/livepatch/core.c b/kernel/livepatch/core.c
index 42f7e716d56bf72..cb7abc821a50584 100644
--- a/kernel/livepatch/core.c
+++ b/kernel/livepatch/core.c
@@ -1041,9 +1041,9 @@ int klp_enable_patch(struct klp_patch *patch)
 	mutex_lock(&klp_mutex);
 
 	if (!klp_is_patch_compatible(patch)) {
+		mutex_unlock(&klp_mutex);
 		pr_err("Livepatch patch (%s) is not compatible with the already installed livepatches.\n",
 			patch->mod->name);
-		mutex_unlock(&klp_mutex);
 		return -EINVAL;
 	}
 
-- 
2.25.1