linux-kernel - [PATCH 3/5] s390: make cpu

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Date:   Fri, 21 Oct 2016 13:58:56 +0200
From:   Christian Borntraeger <borntraeger@...ibm.com>
To:     Peter Zijlstra <peterz@...radead.org>
Cc:     Nicholas Piggin <npiggin@...il.com>, linux-kernel@...r.kernel.org,
        linux-s390 <linux-s390@...r.kernel.org>,
        linux-arch@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org,
        Heiko Carstens <heiko.carstens@...ibm.com>,
        Martin Schwidefsky <schwidefsky@...ibm.com>,
        Noam Camus <noamc@...hip.com>,
        Christian Borntraeger <borntraeger@...ibm.com>
Subject: [PATCH 3/5] s390: make cpu_relax a barrier again

stop_machine seems to be the only important place for yielding during
cpu_relax. This was fixed by using cpu_relax_yield. Therefore, we can
now redefine cpu_relax to be a barrier instead. (With the option to do
some SMT tuning later on)

Signed-off-by: Christian Borntraeger <borntraeger@...ibm.com>
---
 arch/s390/include/asm/processor.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/s390/include/asm/processor.h b/arch/s390/include/asm/processor.h
index d05965b..5d262cf 100644
--- a/arch/s390/include/asm/processor.h
+++ b/arch/s390/include/asm/processor.h
@@ -236,7 +236,7 @@ static inline unsigned short stap(void)
  */
 void cpu_relax_yield(void);
 
-#define cpu_relax() cpu_relax_yield()
+#define cpu_relax() barrier()
 #define cpu_relax_lowlatency()  barrier()
 
 #define ECAG_CACHE_ATTRIBUTE	0
-- 
2.5.5