linux-kernel - [PATCH v3 04/10] x86/mce/threshold: Remove the redundant this_cpu_dec

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Message-Id: <20241025024602.24318-5-qiuxu.zhuo@intel.com>
Date: Fri, 25 Oct 2024 10:45:56 +0800
From: Qiuxu Zhuo <qiuxu.zhuo@...el.com>
To: bp@...en8.de,
	tony.luck@...el.com
Cc: tglx@...utronix.de,
	dave.hansen@...ux.intel.com,
	mingo@...hat.com,
	hpa@...or.com,
	x86@...nel.org,
	linux-edac@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	qiuxu.zhuo@...el.com
Subject: [PATCH v3 04/10] x86/mce/threshold: Remove the redundant this_cpu_dec_return()

The 'storm' variable points to this_cpu_ptr(&storm_desc). Access the
'stormy_bank_count' field through the 'storm' to avoid calling
this_cpu_*() on the same per-CPU variable twice.

This minor optimization reduces the text size by 16 bytes.

  $ size threshold.o.*
     text	   data	    bss	    dec	    hex	filename
     1395	   1664	      0	   3059	    bf3	threshold.o.old
     1379	   1664	      0	   3043	    be3	threshold.o.new

No functional changes intended.

Reviewed-by: Tony Luck <tony.luck@...el.com>
Reviewed-by: Nikolay Borisov <nik.borisov@...e.com>
Reviewed-by: Sohil Mehta <sohil.mehta@...el.com>
Signed-off-by: Qiuxu Zhuo <qiuxu.zhuo@...el.com>
---
Changes in v3:
  - Collect "Reviewed-by:" from Nikolay & Sohil.

Changes in v2:
  - Collect "Reviewed-by:" from Tony.

 arch/x86/kernel/cpu/mce/threshold.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/kernel/cpu/mce/threshold.c b/arch/x86/kernel/cpu/mce/threshold.c
index 89e31e1e5c9c..f4a007616468 100644
--- a/arch/x86/kernel/cpu/mce/threshold.c
+++ b/arch/x86/kernel/cpu/mce/threshold.c
@@ -90,7 +90,7 @@ void cmci_storm_end(unsigned int bank)
 	storm->banks[bank].in_storm_mode = false;
 
 	/* If no banks left in storm mode, stop polling. */
-	if (!this_cpu_dec_return(storm_desc.stormy_bank_count))
+	if (!--storm->stormy_bank_count)
 		mce_timer_kick(false);
 }
 
-- 
2.17.1