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

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Message-Id: <1619165686-69955-1-git-send-email-zhouchuangao@vivo.com>
Date:   Fri, 23 Apr 2021 01:14:45 -0700
From:   zhouchuangao <zhouchuangao@...o.com>
To:     Wei Xu <xuwei5@...ilicon.com>,
        Russell King <linux@...linux.org.uk>,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Cc:     zhouchuangao <zhouchuangao@...o.com>
Subject: [PATCH] arm/mach-hisi: Use BUG_ON instead of if condition followed by BUG

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>
---
 arch/arm/mach-hisi/hotplug.c  | 3 +--
 arch/arm/mach-hisi/platmcpm.c | 4 ++--
 2 files changed, 3 insertions(+), 4 deletions(-)

diff --git a/arch/arm/mach-hisi/hotplug.c b/arch/arm/mach-hisi/hotplug.c
index c517941..b9ced60 100644
--- a/arch/arm/mach-hisi/hotplug.c
+++ b/arch/arm/mach-hisi/hotplug.c
@@ -193,8 +193,7 @@ void hix5hd2_set_cpu(int cpu, bool enable)
 	u32 val = 0;
 
 	if (!ctrl_base)
-		if (!hix5hd2_hotplug_init())
-			BUG();
+		BUG_ON(!hix5hd2_hotplug_init());
 
 	if (enable) {
 		/* power on cpu1 */
diff --git a/arch/arm/mach-hisi/platmcpm.c b/arch/arm/mach-hisi/platmcpm.c
index 96a4840..6c90039 100644
--- a/arch/arm/mach-hisi/platmcpm.c
+++ b/arch/arm/mach-hisi/platmcpm.c
@@ -82,8 +82,8 @@ static void hip04_set_snoop_filter(unsigned int cluster, unsigned int on)
 {
 	unsigned long data;
 
-	if (!fabric)
-		BUG();
+	BUG_ON(!fabric);
+
 	data = readl_relaxed(fabric + FAB_SF_MODE);
 	if (on)
 		data |= 1 << cluster;
-- 
2.7.4