From: Christian Borntraeger <borntraeger@de.ibm.com>
Date: Tue, 25 Oct 2016 09:03:13 +0000 (+0200)
Subject: locking/core, s390: Make cpu_relax() a barrier again
X-Git-Tag: v4.10-rc1~192^2~25
X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=22b6430d36659b37ed139b7fd87fcc7237fb0cfd;p=karo-tx-linux.git

locking/core, s390: Make cpu_relax() a barrier again

stop_machine() seemed 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 on s390,
making s390 identical to all other architectures.

Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Noam Camus <noamc@ezchip.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Will Deacon <will.deacon@arm.com>
Cc: linuxppc-dev@lists.ozlabs.org
Cc: virtualization@lists.linux-foundation.org
Cc: xen-devel@lists.xenproject.org
Link: http://lkml.kernel.org/r/1477386195-32736-4-git-send-email-borntraeger@de.ibm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---

diff --git a/arch/s390/include/asm/processor.h b/arch/s390/include/asm/processor.h
index 5bb44333d320..79343e37b455 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