From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Hildenbrand Subject: [PATCH v1 10/15] arm/futex: UP futex_atomic_cmpxchg_inatomic() relies on disabled preemption Date: Mon, 11 May 2015 17:52:15 +0200 Message-ID: <1431359540-32227-11-git-send-email-dahi@linux.vnet.ibm.com> References: <1431359540-32227-1-git-send-email-dahi@linux.vnet.ibm.com> Return-path: In-Reply-To: <1431359540-32227-1-git-send-email-dahi@linux.vnet.ibm.com> Sender: owner-linux-mm@kvack.org To: linux-kernel@vger.kernel.org Cc: mingo@redhat.com, yang.shi@windriver.com, bigeasy@linutronix.de, benh@kernel.crashing.org, paulus@samba.org, akpm@linux-foundation.org, heiko.carstens@de.ibm.com, schwidefsky@de.ibm.com, borntraeger@de.ibm.com, mst@redhat.com, tglx@linutronix.de, David.Laight@ACULAB.COM, hughd@google.com, hocko@suse.cz, ralf@linux-mips.org, herbert@gondor.apana.org.au, linux@arm.linux.org.uk, airlied@linux.ie, daniel.vetter@intel.com, linux-mm@kvack.org, linux-arch@vger.kernel.org, peterz@infradead.org, dahi@linux.vnet.ibm.com List-Id: linux-arch.vger.kernel.org The !CONFIG_SMP implementation of futex_atomic_cmpxchg_inatomic() requires preemption to be disabled to guarantee mutual exclusion. Let's make this explicit. This patch is based on a patch by Sebastian Andrzej Siewior on the -rt branch. Signed-off-by: David Hildenbrand --- arch/arm/include/asm/futex.h | 3 +++ 1 file changed, 3 insertions(+) diff --git a/arch/arm/include/asm/futex.h b/arch/arm/include/asm/futex.h index 4e78065..255bfd1 100644 --- a/arch/arm/include/asm/futex.h +++ b/arch/arm/include/asm/futex.h @@ -93,6 +93,7 @@ futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr, if (!access_ok(VERIFY_WRITE, uaddr, sizeof(u32))) return -EFAULT; + preempt_disable(); __asm__ __volatile__("@futex_atomic_cmpxchg_inatomic\n" "1: " TUSER(ldr) " %1, [%4]\n" " teq %1, %2\n" @@ -104,6 +105,8 @@ futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr, : "cc", "memory"); *uval = val; + preempt_enable(); + return ret; } -- 2.1.4 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from e06smtp12.uk.ibm.com ([195.75.94.108]:45600 "EHLO e06smtp12.uk.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754038AbbEKPw5 (ORCPT ); Mon, 11 May 2015 11:52:57 -0400 Received: from /spool/local by e06smtp12.uk.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Mon, 11 May 2015 16:52:56 +0100 From: David Hildenbrand Subject: [PATCH v1 10/15] arm/futex: UP futex_atomic_cmpxchg_inatomic() relies on disabled preemption Date: Mon, 11 May 2015 17:52:15 +0200 Message-ID: <1431359540-32227-11-git-send-email-dahi@linux.vnet.ibm.com> In-Reply-To: <1431359540-32227-1-git-send-email-dahi@linux.vnet.ibm.com> References: <1431359540-32227-1-git-send-email-dahi@linux.vnet.ibm.com> Sender: linux-arch-owner@vger.kernel.org List-ID: To: linux-kernel@vger.kernel.org Cc: mingo@redhat.com, yang.shi@windriver.com, bigeasy@linutronix.de, benh@kernel.crashing.org, paulus@samba.org, akpm@linux-foundation.org, heiko.carstens@de.ibm.com, schwidefsky@de.ibm.com, borntraeger@de.ibm.com, mst@redhat.com, tglx@linutronix.de, David.Laight@ACULAB.COM, hughd@google.com, hocko@suse.cz, ralf@linux-mips.org, herbert@gondor.apana.org.au, linux@arm.linux.org.uk, airlied@linux.ie, daniel.vetter@intel.com, linux-mm@kvack.org, linux-arch@vger.kernel.org, peterz@infradead.org, dahi@linux.vnet.ibm.com Message-ID: <20150511155215.PvtZmG65gskkkUa0O88g4e0fcO7TdiXZlGnNp1lOaq0@z> The !CONFIG_SMP implementation of futex_atomic_cmpxchg_inatomic() requires preemption to be disabled to guarantee mutual exclusion. Let's make this explicit. This patch is based on a patch by Sebastian Andrzej Siewior on the -rt branch. Signed-off-by: David Hildenbrand --- arch/arm/include/asm/futex.h | 3 +++ 1 file changed, 3 insertions(+) diff --git a/arch/arm/include/asm/futex.h b/arch/arm/include/asm/futex.h index 4e78065..255bfd1 100644 --- a/arch/arm/include/asm/futex.h +++ b/arch/arm/include/asm/futex.h @@ -93,6 +93,7 @@ futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr, if (!access_ok(VERIFY_WRITE, uaddr, sizeof(u32))) return -EFAULT; + preempt_disable(); __asm__ __volatile__("@futex_atomic_cmpxchg_inatomic\n" "1: " TUSER(ldr) " %1, [%4]\n" " teq %1, %2\n" @@ -104,6 +105,8 @@ futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr, : "cc", "memory"); *uval = val; + preempt_enable(); + return ret; } -- 2.1.4