From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wg0-f41.google.com (mail-wg0-f41.google.com [74.125.82.41]) by kanga.kvack.org (Postfix) with ESMTP id 1715A6B009B for ; Wed, 6 May 2015 13:58:51 -0400 (EDT) Received: by wgyo15 with SMTP id o15so20053292wgy.2 for ; Wed, 06 May 2015 10:58:50 -0700 (PDT) Received: from e06smtp12.uk.ibm.com (e06smtp12.uk.ibm.com. [195.75.94.108]) by mx.google.com with ESMTPS id sa4si35185181wjb.60.2015.05.06.10.50.56 for (version=TLSv1 cipher=AES128-SHA bits=128/128); Wed, 06 May 2015 10:50:57 -0700 (PDT) Received: from /spool/local by e06smtp12.uk.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Wed, 6 May 2015 18:50:56 +0100 Received: from b06cxnps4075.portsmouth.uk.ibm.com (d06relay12.portsmouth.uk.ibm.com [9.149.109.197]) by d06dlp02.portsmouth.uk.ibm.com (Postfix) with ESMTP id 031632190061 for ; Wed, 6 May 2015 18:50:35 +0100 (BST) Received: from d06av05.portsmouth.uk.ibm.com (d06av05.portsmouth.uk.ibm.com [9.149.37.229]) by b06cxnps4075.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id t46HormX49086620 for ; Wed, 6 May 2015 17:50:53 GMT Received: from d06av05.portsmouth.uk.ibm.com (localhost [127.0.0.1]) by d06av05.portsmouth.uk.ibm.com (8.14.4/8.14.4/NCO v10.0 AVout) with ESMTP id t46Hoptw028067 for ; Wed, 6 May 2015 11:50:52 -0600 From: David Hildenbrand Subject: [PATCH RFC 15/15] uaccess: decouple preemption from the pagefault logic Date: Wed, 6 May 2015 19:50:39 +0200 Message-Id: <1430934639-2131-16-git-send-email-dahi@linux.vnet.ibm.com> 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> Sender: owner-linux-mm@kvack.org List-ID: 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 As the fault handlers now all rely on the pagefault_disabled() checks and implicit preempt_disable() calls by pagefault_disable() have been made explicit, we can completely rely on the pagefault_disableD counter. So let's no longer touch the preempt count when disabling/enabling pagefaults. After a call to pagefault_disable(), pagefault_disabled() will return true, but in_atomic() won't. Signed-off-by: David Hildenbrand --- include/linux/uaccess.h | 16 ++-------------- 1 file changed, 2 insertions(+), 14 deletions(-) diff --git a/include/linux/uaccess.h b/include/linux/uaccess.h index 23290cc..83f2a7b 100644 --- a/include/linux/uaccess.h +++ b/include/linux/uaccess.h @@ -1,7 +1,6 @@ #ifndef __LINUX_UACCESS_H__ #define __LINUX_UACCESS_H__ -#include #include #include @@ -20,17 +19,11 @@ static __always_inline void pagefault_disabled_dec(void) * These routines enable/disable the pagefault handler. If disabled, it will * not take any locks and go straight to the fixup table. * - * We increase the preempt and the pagefault count, to be able to distinguish - * whether we run in simple atomic context or in a real pagefault_disable() - * context. - * - * For now, after pagefault_disabled() has been called, we run in atomic - * context. User access methods will not sleep. - * + * User access methods will not sleep when called from a pagefault_disabled() + * environment. */ static inline void pagefault_disable(void) { - preempt_count_inc(); pagefault_disabled_inc(); /* * make sure to have issued the store before a pagefault @@ -47,11 +40,6 @@ static inline void pagefault_enable(void) */ barrier(); pagefault_disabled_dec(); -#ifndef CONFIG_PREEMPT - preempt_count_dec(); -#else - preempt_enable(); -#endif } /* -- 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