linux-kernel - [PATCH 3/5] s390/cmpxchg: remove digits from input constraints

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Date:   Wed, 2 Nov 2022 15:18:07 +0100
From:   Heiko Carstens <hca@...ux.ibm.com>
To:     Heiko Carstens <hca@...ux.ibm.com>
Cc:     Janis Schoetterl-Glausch <scgl@...ux.ibm.com>,
        Christian Borntraeger <borntraeger@...ux.ibm.com>,
        Janosch Frank <frankja@...ux.ibm.com>,
        Claudio Imbrenda <imbrenda@...ux.ibm.com>,
        Vasily Gorbik <gor@...ux.ibm.com>,
        Alexander Gordeev <agordeev@...ux.ibm.com>,
        David Hildenbrand <david@...hat.com>,
        Jonathan Corbet <corbet@....net>, kvm@...r.kernel.org,
        linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-kselftest@...r.kernel.org, linux-s390@...r.kernel.org,
        Paolo Bonzini <pbonzini@...hat.com>,
        Shuah Khan <shuah@...nel.org>,
        Sven Schnelle <svens@...ux.ibm.com>
Subject: [PATCH 3/5] s390/cmpxchg: remove digits from input constraints

Instead of using a digit for input constraints simply initialize the
corresponding output operand in C code and use a "+" constraint
modifier.

Signed-off-by: Heiko Carstens <hca@...ux.ibm.com>
---
 arch/s390/include/asm/cmpxchg.h | 14 ++++++--------
 1 file changed, 6 insertions(+), 8 deletions(-)

diff --git a/arch/s390/include/asm/cmpxchg.h b/arch/s390/include/asm/cmpxchg.h
index 2ad057b94481..1c5785b851ec 100644
--- a/arch/s390/include/asm/cmpxchg.h
+++ b/arch/s390/include/asm/cmpxchg.h
@@ -142,26 +142,24 @@ static __always_inline unsigned long __cmpxchg(unsigned long address,
 		return prev >> shift;
 	}
 	case 4: {
-		unsigned int prev;
+		unsigned int prev = old;
 
 		asm volatile(
 			"	cs	%[prev],%[new],%[address]\n"
-			: [prev] "=&d" (prev),
+			: [prev] "+&d" (prev),
 			  [address] "+Q" (*(int *)address)
-			: "0" (old),
-			  [new] "d" (new)
+			: [new] "d" (new)
 			: "memory", "cc");
 		return prev;
 	}
 	case 8: {
-		unsigned long prev;
+		unsigned long prev = old;
 
 		asm volatile(
 			"	csg	%[prev],%[new],%[address]\n"
-			: [prev] "=&d" (prev),
+			: [prev] "+&d" (prev),
 			  [address] "+QS" (*(long *)address)
-			: "0" (old),
-			  [new] "d" (new)
+			: [new] "d" (new)
 			: "memory", "cc");
 		return prev;
 	}
-- 
2.34.1