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[PATCH 3.2 16/87] powerpc: Make {cmp}xchg* and their atomic_ versions fully ordered

From Ben Hutchings <ben@decadent.org.uk>
Newsgroups linux.kernel
Subject [PATCH 3.2 16/87] powerpc: Make {cmp}xchg* and their atomic_ versions fully ordered
Date 2016-02-09 01:30 +0100
Message-ID <r04lS-4r7-49@gated-at.bofh.it> (permalink)
References <r03SN-3V2-7@gated-at.bofh.it>
Organization linux.* mail to news gateway

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3.2.77-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Boqun Feng <boqun.feng@gmail.com>

commit 81d7a3294de7e9828310bbf986a67246b13fa01e upstream.

According to memory-barriers.txt, xchg*, cmpxchg* and their atomic_
versions all need to be fully ordered, however they are now just
RELEASE+ACQUIRE, which are not fully ordered.

So also 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 fully ordered semantics
of atomic{,64}_{cmp,}xchg() and {cmp,}xchg(), as a complement of commit
b97021f85517 ("powerpc: Fix atomic_xxx_return barrier semantics")

This patch depends on patch "powerpc: Make value-returning atomics fully
ordered" for PPC_ATOMIC_ENTRY_BARRIER definition.

Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
Reviewed-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
[bwh: backported to 3.2: adjust filename]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
 arch/powerpc/include/asm/system.h | 16 ++++++++--------
 1 file changed, 8 insertions(+), 8 deletions(-)

--- a/arch/powerpc/include/asm/system.h
+++ b/arch/powerpc/include/asm/system.h
@@ -234,12 +234,12 @@ __xchg_u32(volatile void *p, unsigned lo
 	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");
@@ -277,12 +277,12 @@ __xchg_u64(volatile void *p, unsigned lo
 	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");
@@ -368,14 +368,14 @@ __cmpxchg_u32(volatile unsigned int *p,
 	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)
@@ -414,13 +414,13 @@ __cmpxchg_u64(volatile unsigned long *p,
 	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)

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[PATCH 3.2 00/87] 3.2.77-rc1 review Ben Hutchings <ben@decadent.org.uk> - 2016-02-09 01:20 +0100
  [PATCH 3.2 79/87] crypto: af_alg - Forbid bind(2) when nokey  child sockets are present Ben Hutchings <ben@decadent.org.uk> - 2016-02-09 01:20 +0100
  [PATCH 3.2 17/87] asix: silence log message from oversize packet Ben Hutchings <ben@decadent.org.uk> - 2016-02-09 01:20 +0100
  [PATCH 3.2 73/87] crypto: algif_hash - Require setkey before  accept(2) Ben Hutchings <ben@decadent.org.uk> - 2016-02-09 01:20 +0100
  [PATCH 3.2 18/87] futex: Drop refcount if requeue_pi() acquired  the rtmutex Ben Hutchings <ben@decadent.org.uk> - 2016-02-09 01:20 +0100
  [PATCH 3.2 60/87] crypto: af_alg - Fix socket double-free when  accept fails Ben Hutchings <ben@decadent.org.uk> - 2016-02-09 01:20 +0100
  [PATCH 3.2 72/87] crypto: hash - Add crypto_ahash_has_setkey Ben Hutchings <ben@decadent.org.uk> - 2016-02-09 01:20 +0100
  [PATCH 3.2 70/87] crypto: af_alg - Add nokey compatibility path Ben Hutchings <ben@decadent.org.uk> - 2016-02-09 01:20 +0100
  [PATCH 3.2 57/87] ALSA: timer: Harden slave timer list handling Ben Hutchings <ben@decadent.org.uk> - 2016-02-09 01:20 +0100
  [PATCH 3.2 61/87] ALSA: hrtimer: Fix stall by hrtimer_cancel() Ben Hutchings <ben@decadent.org.uk> - 2016-02-09 01:20 +0100
  [PATCH 3.2 82/87] crypto: algif_skcipher - Load TX SG list after  waiting Ben Hutchings <ben@decadent.org.uk> - 2016-02-09 01:20 +0100
  [PATCH 3.2 11/87] rtlwifi: fix memory leak for USB device Ben Hutchings <ben@decadent.org.uk> - 2016-02-09 01:20 +0100
  [PATCH 3.2 64/87] ALSA: control: Avoid kernel warnings from tlv  ioctl with numid 0 Ben Hutchings <ben@decadent.org.uk> - 2016-02-09 01:20 +0100
  [PATCH 3.2 01/87] [media] gspca: ov534/topro: prevent a division by 0 Ben Hutchings <ben@decadent.org.uk> - 2016-02-09 01:20 +0100
  [PATCH 3.2 08/87] mtd: nand: fix ONFI parameter page layout Ben Hutchings <ben@decadent.org.uk> - 2016-02-09 01:30 +0100
  [PATCH 3.2 80/87] crypto: algif_hash - Fix race condition in  hash_check_key Ben Hutchings <ben@decadent.org.uk> - 2016-02-09 01:30 +0100
  [PATCH 3.2 04/87] SCSI: initio: remove duplicate module device table Ben Hutchings <ben@decadent.org.uk> - 2016-02-09 01:30 +0100
  [PATCH 3.2 87/87] [media] usbvision: fix crash on detecting  device with invalid configuration Ben Hutchings <ben@decadent.org.uk> - 2016-02-09 01:30 +0100
  [PATCH 3.2 15/87] powerpc: Make value-returning atomics fully ordered Ben Hutchings <ben@decadent.org.uk> - 2016-02-09 01:30 +0100
  [PATCH 3.2 10/87] xhci: refuse loading if nousb is used Ben Hutchings <ben@decadent.org.uk> - 2016-02-09 01:30 +0100
  [PATCH 3.2 05/87] KVM: x86: expose MSR_TSC_AUX to userspace Ben Hutchings <ben@decadent.org.uk> - 2016-02-09 01:30 +0100
  [PATCH 3.2 86/87] [media] usbvision fix overflow of interfaces array Ben Hutchings <ben@decadent.org.uk> - 2016-02-09 01:30 +0100
  [PATCH 3.2 85/87] [media] usbvision: fix leak of usb_dev on  failure paths in  usbvision_probe() Ben Hutchings <ben@decadent.org.uk> - 2016-02-09 01:30 +0100
  [PATCH 3.2 07/87] ath9k_htc: check for underflow in  ath9k_htc_rx_msg() Ben Hutchings <ben@decadent.org.uk> - 2016-02-09 01:30 +0100
  [PATCH 3.2 13/87] wlcore/wl12xx: spi: fix oops on firmware load Ben Hutchings <ben@decadent.org.uk> - 2016-02-09 01:30 +0100
  [PATCH 3.2 14/87] EDAC: Robustify workqueues destruction Ben Hutchings <ben@decadent.org.uk> - 2016-02-09 01:30 +0100
  [PATCH 3.2 19/87] ALSA: fm801: propagate TUNER_ONLY bit when  autodetected Ben Hutchings <ben@decadent.org.uk> - 2016-02-09 01:30 +0100
  [PATCH 3.2 84/87] [media] usbvision-video: fix memory leak of  alt_max_pkt_size Ben Hutchings <ben@decadent.org.uk> - 2016-02-09 01:30 +0100
  [PATCH 3.2 12/87] wlcore: SPI - fix spi transfer_list Ben Hutchings <ben@decadent.org.uk> - 2016-02-09 01:30 +0100
  [PATCH 3.2 16/87] powerpc: Make {cmp}xchg* and their atomic_  versions fully ordered Ben Hutchings <ben@decadent.org.uk> - 2016-02-09 01:30 +0100
  [PATCH 3.2 78/87] crypto: algif_skcipher - Remove custom release  parent function Ben Hutchings <ben@decadent.org.uk> - 2016-02-09 01:30 +0100
  [PATCH 3.2 03/87] [media] rc: allow rc modules to be loaded if  rc-main is not a module Ben Hutchings <ben@decadent.org.uk> - 2016-02-09 01:30 +0100
  Re: [PATCH 3.2 00/87] 3.2.77-rc1 review Guenter Roeck <linux@roeck-us.net> - 2016-02-09 05:00 +0100
    Re: [PATCH 3.2 00/87] 3.2.77-rc1 review Ben Hutchings <ben@decadent.org.uk> - 2016-02-10 02:10 +0100

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