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From: zhouchuangao <zhouchuangao@vivo.com>
To: Wei Xu <xuwei5@hisilicon.com>,
	Russell King <linux@armlinux.org.uk>,
	linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org
Cc: zhouchuangao <zhouchuangao@vivo.com>
Subject: [PATCH] arm/mach-hisi: Use BUG_ON instead of if condition followed by BUG
Date: Fri, 23 Apr 2021 01:14:45 -0700	[thread overview]
Message-ID: <1619165686-69955-1-git-send-email-zhouchuangao@vivo.com> (raw)

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@vivo.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


             reply	other threads:[~2021-04-23  8:14 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-04-23  8:14 zhouchuangao [this message]
2021-04-23 12:16 ` [PATCH] arm/mach-hisi: Use BUG_ON instead of if condition followed by BUG Robin Murphy
2021-04-23 13:10   ` 周传高

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