From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: linux-kernel@vger.kernel.org
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
stable@vger.kernel.org, Boqun Feng <boqun.feng@gmail.com>,
"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
"Peter Zijlstra (Intel)" <peterz@infradead.org>,
Michael Ellerman <mpe@ellerman.id.au>
Subject: [PATCH 3.10 44/53] powerpc: Make value-returning atomics fully ordered
Date: Wed, 27 Jan 2016 10:16:03 -0800 [thread overview]
Message-ID: <20160127180651.162846985@linuxfoundation.org> (raw)
In-Reply-To: <20160127180648.932559859@linuxfoundation.org>
3.10-stable review patch. If anyone has any objections, please let me know.
------------------
From: Boqun Feng <boqun.feng@gmail.com>
commit 49e9cf3f0c04bf76ffa59242254110309554861d upstream.
According to memory-barriers.txt:
> Any atomic operation that modifies some state in memory and returns
> information about the state (old or new) implies an SMP-conditional
> general memory barrier (smp_mb()) on each side of the actual
> operation ...
Which mean these operations should be fully ordered. However on PPC,
PPC_ATOMIC_ENTRY_BARRIER is the barrier before the actual operation,
which is currently "lwsync" if SMP=y. The leading "lwsync" can not
guarantee fully ordered atomics, according to Paul Mckenney:
https://lkml.org/lkml/2015/10/14/970
To fix this, we define PPC_ATOMIC_ENTRY_BARRIER as "sync" to guarantee
the fully-ordered semantics.
This also makes futex atomics fully ordered, which can avoid possible
memory ordering problems if userspace code relies on futex system call
for fully ordered semantics.
Fixes: b97021f85517 ("powerpc: Fix atomic_xxx_return barrier semantics")
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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
arch/powerpc/include/asm/synch.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/arch/powerpc/include/asm/synch.h
+++ b/arch/powerpc/include/asm/synch.h
@@ -44,7 +44,7 @@ static inline void isync(void)
MAKE_LWSYNC_SECTION_ENTRY(97, __lwsync_fixup);
#define PPC_ACQUIRE_BARRIER "\n" stringify_in_c(__PPC_ACQUIRE_BARRIER)
#define PPC_RELEASE_BARRIER stringify_in_c(LWSYNC) "\n"
-#define PPC_ATOMIC_ENTRY_BARRIER "\n" stringify_in_c(LWSYNC) "\n"
+#define PPC_ATOMIC_ENTRY_BARRIER "\n" stringify_in_c(sync) "\n"
#define PPC_ATOMIC_EXIT_BARRIER "\n" stringify_in_c(sync) "\n"
#else
#define PPC_ACQUIRE_BARRIER
next prev parent reply other threads:[~2016-01-27 18:16 UTC|newest]
Thread overview: 60+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-01-27 18:15 [PATCH 3.10 00/53] 3.10.96-stable review Greg Kroah-Hartman
2016-01-27 18:15 ` [PATCH 3.10 01/53] af_unix: fix incorrect revert of lock_interruptible in stream receive code Greg Kroah-Hartman
2016-01-27 18:15 ` [PATCH 3.10 02/53] x86/signal: Fix restart_syscall number for x32 tasks Greg Kroah-Hartman
2016-01-27 18:15 ` [PATCH 3.10 03/53] xen/gntdev: Grant maps should not be subject to NUMA balancing Greg Kroah-Hartman
2016-01-27 18:15 ` [PATCH 3.10 04/53] x86/xen: dont reset vcpu_info on a cancelled suspend Greg Kroah-Hartman
2016-01-27 18:15 ` [PATCH 3.10 05/53] KVM: PPC: Book3S HV: Prohibit setting illegal transaction state in MSR Greg Kroah-Hartman
2016-01-27 18:15 ` [PATCH 3.10 06/53] x86/reboot/quirks: Add iMac10,1 to pci_reboot_dmi_table[] Greg Kroah-Hartman
2016-01-27 18:15 ` [PATCH 3.10 07/53] x86/boot: Double BOOT_HEAP_SIZE to 64KB Greg Kroah-Hartman
2016-01-27 18:15 ` [PATCH 3.10 08/53] ipmi: move timer init to before irq is setup Greg Kroah-Hartman
2016-01-27 18:15 ` [PATCH 3.10 09/53] ALSA: hda - Add Intel Lewisburg device IDs Audio Greg Kroah-Hartman
2016-01-27 18:15 ` [PATCH 3.10 10/53] ALSA: hda - Apply pin fixup for HP ProBook 6550b Greg Kroah-Hartman
2016-01-27 18:15 ` [PATCH 3.10 11/53] ALSA: rme96: Fix unexpected volume reset after rate changes Greg Kroah-Hartman
2016-01-27 18:15 ` [PATCH 3.10 12/53] ALSA: hda - Add inverted dmic for Packard Bell DOTS Greg Kroah-Hartman
2016-01-27 18:15 ` [PATCH 3.10 13/53] ALSA: hda - Set SKL+ hda controller power at freeze() and thaw() Greg Kroah-Hartman
2016-01-27 18:15 ` [PATCH 3.10 14/53] ALSA: hda/realtek - Fix silent headphone output on MacPro 4,1 (v2) Greg Kroah-Hartman
2016-01-27 18:15 ` [PATCH 3.10 15/53] ALSA: seq: Fix missing NULL check at remove_events ioctl Greg Kroah-Hartman
2016-01-27 18:15 ` [PATCH 3.10 16/53] ALSA: seq: Fix race at timer setup and close Greg Kroah-Hartman
2016-01-27 18:15 ` [PATCH 3.10 17/53] ALSA: timer: Harden slave timer list handling Greg Kroah-Hartman
2016-01-27 18:15 ` [PATCH 3.10 18/53] ALSA: timer: Fix race among timer ioctls Greg Kroah-Hartman
2016-01-27 18:15 ` [PATCH 3.10 19/53] ALSA: timer: Fix double unlink of active_list Greg Kroah-Hartman
2016-01-27 18:15 ` [PATCH 3.10 20/53] ALSA: seq: Fix snd_seq_call_port_info_ioctl in compat mode Greg Kroah-Hartman
2016-01-27 18:15 ` [PATCH 3.10 21/53] ALSA: pcm: Fix snd_pcm_hw_params struct copy " Greg Kroah-Hartman
2016-01-27 18:15 ` [PATCH 3.10 22/53] ALSA: hrtimer: Fix stall by hrtimer_cancel() Greg Kroah-Hartman
2016-01-27 18:15 ` [PATCH 3.10 23/53] ALSA: control: Avoid kernel warnings from tlv ioctl with numid 0 Greg Kroah-Hartman
2016-01-27 18:15 ` [PATCH 3.10 24/53] ASoC: wm8962: correct addresses for HPF_C_0/1 Greg Kroah-Hartman
2016-01-27 18:15 ` [PATCH 3.10 25/53] ASoC: arizona: Fix bclk for sample rates that are multiple of 4kHz Greg Kroah-Hartman
2016-01-27 18:15 ` [PATCH 3.10 26/53] ASoC: compress: Fix compress device direction check Greg Kroah-Hartman
2016-01-27 18:15 ` [PATCH 3.10 27/53] usb: xhci: fix config fail of FS hub behind a HS hub with MTT Greg Kroah-Hartman
2016-01-27 18:15 ` [PATCH 3.10 28/53] USB: ipaq.c: fix a timeout loop Greg Kroah-Hartman
2016-01-27 18:15 ` [PATCH 3.10 29/53] USB: cp210x: add ID for ELV Marble Sound Board 1 Greg Kroah-Hartman
2016-01-27 18:15 ` [PATCH 3.10 30/53] xhci: refuse loading if nousb is used Greg Kroah-Hartman
2016-01-27 18:15 ` [PATCH 3.10 32/53] ipv6/addrlabel: fix ip6addrlbl_get() Greg Kroah-Hartman
2016-01-27 18:15 ` [PATCH 3.10 33/53] sctp: sctp should release assoc when sctp_make_abort_user return NULL in sctp_close Greg Kroah-Hartman
2016-01-27 18:15 ` [PATCH 3.10 34/53] connector: bump skb->users before callback invocation Greg Kroah-Hartman
2016-01-27 18:15 ` [PATCH 3.10 35/53] unix: properly account for FDs passed over unix sockets Greg Kroah-Hartman
2016-01-27 18:15 ` [PATCH 3.10 36/53] bridge: Only call /sbin/bridge-stp for the initial network namespace Greg Kroah-Hartman
2016-01-27 18:15 ` [PATCH 3.10 37/53] net: possible use after free in dst_release Greg Kroah-Hartman
2016-01-27 18:15 ` [PATCH 3.10 38/53] tcp_yeah: dont set ssthresh below 2 Greg Kroah-Hartman
2016-01-27 18:15 ` [PATCH 3.10 39/53] phonet: properly unshare skbs in phonet_rcv() Greg Kroah-Hartman
2016-01-27 18:15 ` [PATCH 3.10 40/53] isdn_ppp: Add checks for allocation failure in isdn_ppp_open() Greg Kroah-Hartman
2016-01-27 18:16 ` [PATCH 3.10 42/53] team: Replace rcu_read_lock with a mutex in team_vlan_rx_kill_vid Greg Kroah-Hartman
2016-01-27 18:16 ` [PATCH 3.10 43/53] powerpc/tm: Block signal return setting invalid MSR state Greg Kroah-Hartman
2016-01-27 18:16 ` Greg Kroah-Hartman [this message]
2016-01-27 18:16 ` [PATCH 3.10 45/53] powerpc: Make {cmp}xchg* and their atomic_ versions fully ordered Greg Kroah-Hartman
2016-01-27 18:16 ` [PATCH 3.10 46/53] scripts/recordmcount.pl: support data in text section on powerpc Greg Kroah-Hartman
2016-01-27 18:16 ` [PATCH 3.10 47/53] arm64: fix building without CONFIG_UID16 Greg Kroah-Hartman
2016-01-27 18:16 ` [PATCH 3.10 48/53] arm64: Clear out any singlestep state on a ptrace detach operation Greg Kroah-Hartman
2016-01-27 18:16 ` [PATCH 3.10 49/53] arm64: mm: ensure that the zero page is visible to the page table walker Greg Kroah-Hartman
2016-01-27 18:16 ` [PATCH 3.10 50/53] parisc iommu: fix panic due to trying to allocate too large region Greg Kroah-Hartman
2016-01-27 18:16 ` [PATCH 3.10 51/53] HID: core: Avoid uninitialized buffer access Greg Kroah-Hartman
2016-01-27 18:16 ` [PATCH 3.10 52/53] openrisc: fix CONFIG_UID16 setting Greg Kroah-Hartman
2016-01-27 18:16 ` [PATCH 3.10 53/53] mn10300: Select CONFIG_HAVE_UID16 to fix build failure Greg Kroah-Hartman
2016-01-27 21:11 ` [PATCH 3.10 00/53] 3.10.96-stable review Willy Tarreau
2016-01-27 21:29 ` Greg Kroah-Hartman
2016-01-27 23:29 ` Shuah Khan
2016-01-29 5:48 ` Greg Kroah-Hartman
2016-01-28 1:59 ` Guenter Roeck
2016-01-29 5:55 ` Greg Kroah-Hartman
[not found] ` <56a9f5b3.ccaa1c0a.752ef.ffffb8f7@mx.google.com>
2016-01-29 5:56 ` Greg Kroah-Hartman
2016-01-29 22:47 ` Kevin Hilman
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