From: Boqun Feng <boqun.feng@gmail.com>
To: linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org
Cc: Peter Zijlstra <peterz@infradead.org>,
Ingo Molnar <mingo@kernel.org>,
Benjamin Herrenschmidt <benh@kernel.crashing.org>,
Paul Mackerras <paulus@samba.org>,
Michael Ellerman <mpe@ellerman.id.au>,
Thomas Gleixner <tglx@linutronix.de>,
Will Deacon <will.deacon@arm.com>,
"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
Waiman Long <waiman.long@hp.com>,
Davidlohr Bueso <dave@stgolabs.net>,
Boqun Feng <boqun.feng@gmail.com>, <stable@vger.kernel.org>
Subject: [PATCH RESEND v3 1/6] powerpc: atomic: Make *xchg and *cmpxchg a full barrier
Date: Mon, 12 Oct 2015 22:30:20 +0800 [thread overview]
Message-ID: <1444660220-25559-1-git-send-email-boqun.feng@gmail.com> (raw)
In-Reply-To: <1444659246-24769-1-git-send-email-boqun.feng@gmail.com>
According to memory-barriers.txt, xchg, cmpxchg and their atomic{,64}_
versions all need to imply a full barrier, however they are now just
RELEASE+ACQUIRE, which is not a full barrier.
So replace PPC_RELEASE_BARRIER and PPC_ACQUIRE_BARRIER with
PPC_ATOMIC_ENTRY_BARRIER and PPC_ATOMIC_EXIT_BARRIER in
__{cmp,}xchg_{u32,u64} respectively to guarantee a full barrier
semantics of atomic{,64}_{cmp,}xchg() and {cmp,}xchg().
This patch is a complement of commit b97021f85517 ("powerpc: Fix
atomic_xxx_return barrier semantics").
Cc: <stable@vger.kernel.org> # 3.4.y-
Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
---
arch/powerpc/include/asm/cmpxchg.h | 16 ++++++++--------
1 file changed, 8 insertions(+), 8 deletions(-)
diff --git a/arch/powerpc/include/asm/cmpxchg.h b/arch/powerpc/include/asm/cmpxchg.h
index ad6263c..d1a8d93 100644
--- a/arch/powerpc/include/asm/cmpxchg.h
+++ b/arch/powerpc/include/asm/cmpxchg.h
@@ -18,12 +18,12 @@ __xchg_u32(volatile void *p, unsigned long val)
unsigned long prev;
__asm__ __volatile__(
- PPC_RELEASE_BARRIER
+ PPC_ATOMIC_ENTRY_BARRIER
"1: lwarx %0,0,%2 \n"
PPC405_ERR77(0,%2)
" stwcx. %3,0,%2 \n\
bne- 1b"
- PPC_ACQUIRE_BARRIER
+ PPC_ATOMIC_EXIT_BARRIER
: "=&r" (prev), "+m" (*(volatile unsigned int *)p)
: "r" (p), "r" (val)
: "cc", "memory");
@@ -61,12 +61,12 @@ __xchg_u64(volatile void *p, unsigned long val)
unsigned long prev;
__asm__ __volatile__(
- PPC_RELEASE_BARRIER
+ PPC_ATOMIC_ENTRY_BARRIER
"1: ldarx %0,0,%2 \n"
PPC405_ERR77(0,%2)
" stdcx. %3,0,%2 \n\
bne- 1b"
- PPC_ACQUIRE_BARRIER
+ PPC_ATOMIC_EXIT_BARRIER
: "=&r" (prev), "+m" (*(volatile unsigned long *)p)
: "r" (p), "r" (val)
: "cc", "memory");
@@ -151,14 +151,14 @@ __cmpxchg_u32(volatile unsigned int *p, unsigned long old, unsigned long new)
unsigned int prev;
__asm__ __volatile__ (
- PPC_RELEASE_BARRIER
+ PPC_ATOMIC_ENTRY_BARRIER
"1: lwarx %0,0,%2 # __cmpxchg_u32\n\
cmpw 0,%0,%3\n\
bne- 2f\n"
PPC405_ERR77(0,%2)
" stwcx. %4,0,%2\n\
bne- 1b"
- PPC_ACQUIRE_BARRIER
+ PPC_ATOMIC_EXIT_BARRIER
"\n\
2:"
: "=&r" (prev), "+m" (*p)
@@ -197,13 +197,13 @@ __cmpxchg_u64(volatile unsigned long *p, unsigned long old, unsigned long new)
unsigned long prev;
__asm__ __volatile__ (
- PPC_RELEASE_BARRIER
+ PPC_ATOMIC_ENTRY_BARRIER
"1: ldarx %0,0,%2 # __cmpxchg_u64\n\
cmpd 0,%0,%3\n\
bne- 2f\n\
stdcx. %4,0,%2\n\
bne- 1b"
- PPC_ACQUIRE_BARRIER
+ PPC_ATOMIC_EXIT_BARRIER
"\n\
2:"
: "=&r" (prev), "+m" (*p)
--
2.5.3
next prev parent reply other threads:[~2015-10-12 14:31 UTC|newest]
Thread overview: 40+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-10-12 14:14 [PATCH v3 0/6] atomics: powerpc: Implement relaxed/acquire/release variants of some atomics Boqun Feng
2015-10-12 14:14 ` [PATCH v3 1/6] powerpc: atomic: Make *xchg and *cmpxchg a full barrier Boqun Feng
2015-10-12 14:23 ` Boqun Feng
2015-10-12 14:14 ` [PATCH v3 2/6] atomics: Add test for atomic operations with _relaxed variants Boqun Feng
[not found] ` <201510122205.Uu3yljqf%fengguang.wu@intel.com>
[not found] ` <20151012145652.GJ27351@fixme-laptop.cn.ibm.com>
2015-10-12 15:29 ` [lkp] " Fengguang Wu
2015-10-12 15:42 ` Boqun Feng
2015-10-12 16:02 ` [kbuild-all] " Fengguang Wu
2015-10-12 16:09 ` Fengguang Wu
2015-10-13 1:33 ` Boqun Feng
2015-10-12 14:14 ` [PATCH v3 3/6] atomics: Allow architectures to define their own __atomic_op_* helpers Boqun Feng
2015-10-12 14:14 ` [PATCH v3 4/6] powerpc: atomic: Implement atomic{,64}_*_return_* variants Boqun Feng
2015-10-12 14:14 ` [PATCH v3 4/6] powerpc: atomic: Implement atomic{, 64}_*_return_* variants Boqun Feng
2015-10-13 13:21 ` [PATCH v3 4/6] powerpc: atomic: Implement atomic{,64}_*_return_* variants Will Deacon
2015-10-13 13:21 ` [PATCH v3 4/6] powerpc: atomic: Implement atomic{, 64}_*_return_* variants Will Deacon
2015-10-13 13:35 ` [PATCH v3 4/6] powerpc: atomic: Implement atomic{,64}_*_return_* variants Boqun Feng
2015-10-13 13:35 ` [PATCH v3 4/6] powerpc: atomic: Implement atomic{, 64}_*_return_* variants Boqun Feng
2015-10-14 1:00 ` [PATCH v3 4/6] powerpc: atomic: Implement atomic{,64}_*_return_* variants Boqun Feng
2015-10-14 1:00 ` [PATCH v3 4/6] powerpc: atomic: Implement atomic{, 64}_*_return_* variants Boqun Feng
2015-10-12 14:14 ` [PATCH v3 5/6] powerpc: atomic: Implement xchg_* and atomic{,64}_xchg_* variants Boqun Feng
2015-10-12 14:14 ` [PATCH v3 5/6] powerpc: atomic: Implement xchg_* and atomic{, 64}_xchg_* variants Boqun Feng
2015-10-12 14:14 ` [PATCH v3 6/6] powerpc: atomic: Implement cmpxchg{,64}_* and atomic{,64}_cmpxchg_* variants Boqun Feng
2015-10-12 14:14 ` [PATCH v3 6/6] powerpc: atomic: Implement cmpxchg{, 64}_* and atomic{, 64}_cmpxchg_* variants Boqun Feng
2015-10-13 13:24 ` [PATCH v3 6/6] powerpc: atomic: Implement cmpxchg{,64}_* and atomic{,64}_cmpxchg_* variants Will Deacon
2015-10-13 14:32 ` Boqun Feng
2015-10-13 14:43 ` Will Deacon
2015-10-13 14:58 ` Boqun Feng
2015-10-13 15:04 ` Will Deacon
2015-10-13 15:45 ` Boqun Feng
2015-10-14 1:47 ` Boqun Feng
2015-10-14 9:40 ` Will Deacon
2015-10-13 14:46 ` Boqun Feng
2015-10-12 14:30 ` Boqun Feng [this message]
2015-10-14 0:10 ` [PATCH RESEND v3 1/6] powerpc: atomic: Make *xchg and *cmpxchg a full barrier Michael Ellerman
2015-10-14 0:51 ` Boqun Feng
2015-10-14 8:06 ` Peter Zijlstra
2015-10-14 9:26 ` Boqun Feng
2015-10-14 9:33 ` Peter Zijlstra
2015-10-14 9:43 ` Michael Ellerman
2015-10-13 12:27 ` [PATCH v3 0/6] atomics: powerpc: Implement relaxed/acquire/release variants of some atomics Peter Zijlstra
2015-10-13 15:46 ` Paul E. McKenney
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