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Message-ID: <5D490021.F1CCC042@users.sourceforge.net>
Date:   Tue, 06 Aug 2019 07:20:49 +0300
From:   Jari Ruusu <jariruusu@users.sourceforge.net>
MIME-Version: 1.0
To:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>
CC:     linux-kernel@vger.kernel.org, torvalds@linux-foundation.org,
        akpm@linux-foundation.org, linux@roeck-us.net, shuah@kernel.org,
        patches@kernelci.org, ben.hutchings@codethink.co.uk,
        lkft-triage@lists.linaro.org, stable@vger.kernel.org,
        Peter Zijlstra <peterz@infradead.org>
Subject: Re: [PATCH 4.9 00/42] 4.9.188-stable review
References: <20190805124924.788666484@linuxfoundation.org>
                 <5D488D55.B84FC098@users.sourceforge.net> <20190805201847.GA31714@kroah.com>
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Sender: linux-kernel-owner@vger.kernel.org
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Greg Kroah-Hartman wrote:
> On Mon, Aug 05, 2019 at 11:11:01PM +0300, Jari Ruusu wrote:
> > Peter Zijlstra's "x86/atomic: Fix smp_mb__{before,after}_atomic()"
> > upstream commit 69d927bba39517d0980462efc051875b7f4db185 seems to
> > be missing/lost from 4.9 and older stable kernels.
> 
> Can you send properly backported and tested patches?

linux-4.4 backport of "x86/atomic: Fix smp_mb__{before,after}_atomic()".
Tested.

Signed-off-by: Jari Ruusu <jari.ruusu@gmail.com>

--- a/arch/x86/include/asm/atomic.h
+++ b/arch/x86/include/asm/atomic.h
@@ -49,7 +49,7 @@
 {
 	asm volatile(LOCK_PREFIX "addl %1,%0"
 		     : "+m" (v->counter)
-		     : "ir" (i));
+		     : "ir" (i) : "memory");
 }
 
 /**
@@ -63,7 +63,7 @@
 {
 	asm volatile(LOCK_PREFIX "subl %1,%0"
 		     : "+m" (v->counter)
-		     : "ir" (i));
+		     : "ir" (i) : "memory");
 }
 
 /**
@@ -89,7 +89,7 @@
 static __always_inline void atomic_inc(atomic_t *v)
 {
 	asm volatile(LOCK_PREFIX "incl %0"
-		     : "+m" (v->counter));
+		     : "+m" (v->counter) :: "memory");
 }
 
 /**
@@ -101,7 +101,7 @@
 static __always_inline void atomic_dec(atomic_t *v)
 {
 	asm volatile(LOCK_PREFIX "decl %0"
-		     : "+m" (v->counter));
+		     : "+m" (v->counter) :: "memory");
 }
 
 /**
--- a/arch/x86/include/asm/atomic64_64.h
+++ b/arch/x86/include/asm/atomic64_64.h
@@ -44,7 +44,7 @@
 {
 	asm volatile(LOCK_PREFIX "addq %1,%0"
 		     : "=m" (v->counter)
-		     : "er" (i), "m" (v->counter));
+		     : "er" (i), "m" (v->counter) : "memory");
 }
 
 /**
@@ -58,7 +58,7 @@
 {
 	asm volatile(LOCK_PREFIX "subq %1,%0"
 		     : "=m" (v->counter)
-		     : "er" (i), "m" (v->counter));
+		     : "er" (i), "m" (v->counter) : "memory");
 }
 
 /**
@@ -85,7 +85,7 @@
 {
 	asm volatile(LOCK_PREFIX "incq %0"
 		     : "=m" (v->counter)
-		     : "m" (v->counter));
+		     : "m" (v->counter) : "memory");
 }
 
 /**
@@ -98,7 +98,7 @@
 {
 	asm volatile(LOCK_PREFIX "decq %0"
 		     : "=m" (v->counter)
-		     : "m" (v->counter));
+		     : "m" (v->counter) : "memory");
 }
 
 /**
--- a/arch/x86/include/asm/barrier.h
+++ b/arch/x86/include/asm/barrier.h
@@ -116,7 +116,7 @@
 #endif
 
 /* Atomic operations are already serializing on x86 */
-#define smp_mb__before_atomic()	barrier()
-#define smp_mb__after_atomic()	barrier()
+#define smp_mb__before_atomic()	do { } while (0)
+#define smp_mb__after_atomic()	do { } while (0)
 
 #endif /* _ASM_X86_BARRIER_H */

-- 
Jari Ruusu  4096R/8132F189 12D6 4C3A DCDA 0AA4 27BD  ACDF F073 3C80 8132 F189