Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753304AbbEFRxU (ORCPT ); Wed, 6 May 2015 13:53:20 -0400 Received: from e06smtp10.uk.ibm.com ([195.75.94.106]:37190 "EHLO e06smtp10.uk.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752750AbbEFRux (ORCPT ); Wed, 6 May 2015 13:50:53 -0400 From: David Hildenbrand To: linux-kernel@vger.kernel.org Cc: dahi@linux.vnet.ibm.com, mingo@redhat.com, peterz@infradead.org, 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 Subject: [PATCH RFC 09/15] futex: UP futex_atomic_cmpxchg_inatomic() relies on disabled preemption Date: Wed, 6 May 2015 19:50:33 +0200 Message-Id: <1430934639-2131-10-git-send-email-dahi@linux.vnet.ibm.com> X-Mailer: git-send-email 2.1.4 In-Reply-To: <1430934639-2131-1-git-send-email-dahi@linux.vnet.ibm.com> References: <1430934639-2131-1-git-send-email-dahi@linux.vnet.ibm.com> X-TM-AS-MML: disable X-Content-Scanned: Fidelis XPS MAILER x-cbid: 15050617-0041-0000-0000-0000042821F5 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1255 Lines: 41 Let's explicitly disable/enable preemption in the !CONFIG_SMP version of futex_atomic_cmpxchg_inatomic, to prepare for pagefault_disable() not touching preemption anymore. This is needed for this function to be callable from both, atomic and non-atomic context. Otherwise we might break mutual exclusion when relying on a get_user()/ put_user() implementation. Signed-off-by: David Hildenbrand --- include/asm-generic/futex.h | 2 ++ 1 file changed, 2 insertions(+) diff --git a/include/asm-generic/futex.h b/include/asm-generic/futex.h index 3586017..e56272c 100644 --- a/include/asm-generic/futex.h +++ b/include/asm-generic/futex.h @@ -107,6 +107,7 @@ futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr, { u32 val; + preempt_disable(); if (unlikely(get_user(val, uaddr) != 0)) return -EFAULT; @@ -114,6 +115,7 @@ futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr, return -EFAULT; *uval = val; + preempt_enable(); return 0; } -- 2.1.4 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/