From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S264474AbTLVVXq (ORCPT ); Mon, 22 Dec 2003 16:23:46 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S264479AbTLVVXq (ORCPT ); Mon, 22 Dec 2003 16:23:46 -0500 Received: from users.ccur.com ([208.248.32.211]:52983 "HELO rudolph.ccur.com") by vger.kernel.org with SMTP id S264474AbTLVVXg (ORCPT ); Mon, 22 Dec 2003 16:23:36 -0500 Date: Mon, 22 Dec 2003 16:22:37 -0500 From: Joe Korty To: Rob Love Cc: William Lee Irwin III , Albert Cahalan , linux-kernel mailing list Subject: Re: atomic copy_from_user? Message-ID: <20031222212237.GA2865@rudolph.ccur.com> Reply-To: Joe Korty References: <1072054100.1742.156.camel@cube> <20031222150026.GD27687@holomorphy.com> <20031222182637.GA2659@rudolph.ccur.com> <1072126506.3318.31.camel@fur> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1072126506.3318.31.camel@fur> User-Agent: Mutt/1.4i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Dec 22, 2003 at 03:55:06PM -0500, Rob Love wrote: > On Mon, 2003-12-22 at 13:26, Joe Korty wrote: > > > Shouldn't the dec_prempt_count() in kunmap_atomic() be followed > > by a preempt_check_resched()??? > > Probably. > > Actually, dec_preempt_count() ought to call preempt_check_resched() > itself. In the case of !CONFIG_PREEMPT, that call would simply optimize > away. > > Attached patch is against 2.6.0. > > Rob Love > > > linux/preempt.h | 1 + > 1 files changed, 1 insertion(+) > > diff -urN include/linux/preempt.h.orig include/linux/preempt.h > --- include/linux/preempt.h.orig 2003-12-22 15:53:11.329113296 -0500 > +++ include/linux/preempt.h 2003-12-22 15:53:51.314034664 -0500 > @@ -18,6 +18,7 @@ > #define dec_preempt_count() \ > do { \ > preempt_count()--; \ > + preempt_check_resched(); \ > } while (0) > > #ifdef CONFIG_PREEMPT I am guessing that nowdays even when preemption is disabled one can find preempt_count still being used somewhere. Otherwise it would be better to replace all uses of inc_preempt_count() with preempt_disable() and dec_preempt_count() with preempt_enable(). Joe diff -ura base/arch/i386/mm/highmem.c new/arch/i386/mm/highmem.c --- base/arch/i386/mm/highmem.c 2003-12-17 21:58:56.000000000 -0500 +++ new/arch/i386/mm/highmem.c 2003-12-22 16:16:27.000000000 -0500 @@ -30,7 +30,7 @@ enum fixed_addresses idx; unsigned long vaddr; - inc_preempt_count(); + preempt_disable(); if (page < highmem_start_page) return page_address(page); @@ -53,7 +53,7 @@ enum fixed_addresses idx = type + KM_TYPE_NR*smp_processor_id(); if (vaddr < FIXADDR_START) { // FIXME - dec_preempt_count(); + preempt_enable(); return; } @@ -68,7 +68,7 @@ __flush_tlb_one(vaddr); #endif - dec_preempt_count(); + preempt_enable(); } struct page *kmap_atomic_to_page(void *ptr) diff -ura base/arch/mips/mm/highmem.c new/arch/mips/mm/highmem.c --- base/arch/mips/mm/highmem.c 2003-12-17 21:58:28.000000000 -0500 +++ new/arch/mips/mm/highmem.c 2003-12-22 16:17:28.000000000 -0500 @@ -40,7 +40,7 @@ enum fixed_addresses idx; unsigned long vaddr; - inc_preempt_count(); + preempt_disable(); if (page < highmem_start_page) return page_address(page); @@ -63,7 +63,7 @@ enum fixed_addresses idx = type + KM_TYPE_NR*smp_processor_id(); if (vaddr < FIXADDR_START) { // FIXME - dec_preempt_count(); + preempt_enable(); return; } @@ -78,7 +78,7 @@ local_flush_tlb_one(vaddr); #endif - dec_preempt_count(); + preempt_enable(); } struct page *kmap_atomic_to_page(void *ptr) diff -ura base/arch/sparc/mm/highmem.c new/arch/sparc/mm/highmem.c --- base/arch/sparc/mm/highmem.c 2003-12-17 21:58:28.000000000 -0500 +++ new/arch/sparc/mm/highmem.c 2003-12-22 16:17:02.000000000 -0500 @@ -33,7 +33,7 @@ unsigned long idx; unsigned long vaddr; - inc_preempt_count(); + preempt_disable(); if (page < highmem_start_page) return page_address(page); @@ -68,7 +68,7 @@ unsigned long idx = type + KM_TYPE_NR*smp_processor_id(); if (vaddr < fix_kmap_begin) { // FIXME - dec_preempt_count(); + preempt_enable(); return; } @@ -95,5 +95,5 @@ flush_tlb_all(); #endif #endif - dec_preempt_count(); + preempt_enable(); } diff -ura base/include/asm-ppc/highmem.h new/include/asm-ppc/highmem.h --- base/include/asm-ppc/highmem.h 2003-12-17 21:59:45.000000000 -0500 +++ new/include/asm-ppc/highmem.h 2003-12-22 16:18:05.000000000 -0500 @@ -81,7 +81,7 @@ unsigned int idx; unsigned long vaddr; - inc_preempt_count(); + preempt_disable(); if (page < highmem_start_page) return page_address(page); @@ -104,7 +104,7 @@ unsigned int idx = type + KM_TYPE_NR*smp_processor_id(); if (vaddr < KMAP_FIX_BEGIN) { // FIXME - dec_preempt_count(); + preempt_disable(); return; } @@ -118,7 +118,7 @@ pte_clear(kmap_pte+idx); flush_tlb_page(0, vaddr); #endif - dec_preempt_count(); + preempt_enable(); } static inline struct page *kmap_atomic_to_page(void *ptr)