linux-kernel - [PATCH] kernel/module: Use BUG_ON instead of if condition followed by BUG

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Message-Id: <1620610682-25567-1-git-send-email-zhouchuangao@vivo.com>
Date:   Sun,  9 May 2021 18:38:02 -0700
From:   zhouchuangao <zhouchuangao@...o.com>
To:     jeyu@...nel.org
Cc:     linux-kernel@...r.kernel.org, zhouchuangao <zhouchuangao@...o.com>
Subject: [PATCH] kernel/module: Use BUG_ON instead of if condition followed by BUG

This patch comes from cocinelle warning.

BUG_ON uses unlikely in if(). Through disassembly, we can see that
brk #0x800 is compiled to the end of the function.
As you can see below:
    ......
    ffffff8008660bec:   d65f03c0    ret
    ffffff8008660bf0:   d4210000    brk #0x800

Usually, the condition in if () is not satisfied. For the
multi-stage pipeline, we do not need to perform fetch decode
and excute operation on brk instruction.

In my opinion, this can improve the efficiency of the
multi-stage pipeline.

Signed-off-by: zhouchuangao <zhouchuangao@...o.com>
---
 kernel/module.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/kernel/module.c b/kernel/module.c
index b5dd92e..faf9114 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -1014,8 +1014,7 @@ void __symbol_put(const char *symbol)
 	};
 
 	preempt_disable();
-	if (!find_symbol(&fsa))
-		BUG();
+	BUG_ON(!find_symbol(&fsa));
 	module_put(fsa.owner);
 	preempt_enable();
 }
-- 
2.7.4