Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1765557AbXHFNs7 (ORCPT ); Mon, 6 Aug 2007 09:48:59 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1761970AbXHFNss (ORCPT ); Mon, 6 Aug 2007 09:48:48 -0400 Received: from perninha.conectiva.com.br ([200.140.247.100]:42156 "EHLO perninha.conectiva.com.br" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1761539AbXHFNsr (ORCPT ); Mon, 6 Aug 2007 09:48:47 -0400 Date: Mon, 6 Aug 2007 10:34:58 -0300 From: "Luiz Fernando N. Capitulino" To: Ingo Molnar Cc: Andrew Morton , linux-kernel@vger.kernel.org Subject: Re: [PATCH] i386: convert mm_context_t semaphore to a mutex Message-ID: <20070806103458.4b35c90d@localhost> In-Reply-To: <20070806074608.GA12415@elte.hu> References: <20070803105540.4f85ae09@localhost> <20070806074608.GA12415@elte.hu> Organization: Mandriva X-Mailer: Claws Mail 2.10.0 (GTK+ 2.11.6; i586-mandriva-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4707 Lines: 164 Em Mon, 6 Aug 2007 09:46:08 +0200 Ingo Molnar escreveu: | | > typedef struct { | > int size; | > - struct semaphore sem; | > + struct mutex lock; | | hm, looks good to me but i'm wondering why this was a holdout for such a | long time :-) Did you manage to test actual LDT functionality with this | patch applied? No, I didn't. The only test I did was to run the kernel with this patch applied. I'll manage to test it then. Do you have a test-case or has any suggestion? Oh, btw, I forgot to 'quilt add arch/i386/mm/fault.c' so the patch I sent was incomplete. Fixed version below. Shame on me. [PATCH] i386: convert mm_context_t semaphore to a mutex --- arch/i386/kernel/i386_ksyms.c | 1 + arch/i386/kernel/ldt.c | 14 +++++++------- arch/i386/kernel/ptrace.c | 4 ++-- arch/i386/mm/fault.c | 4 ++-- include/asm-i386/mmu.h | 4 ++-- 5 files changed, 14 insertions(+), 13 deletions(-) --- linux-2.6-lcpt.orig/arch/i386/kernel/ldt.c +++ linux-2.6-lcpt/arch/i386/kernel/ldt.c @@ -94,13 +94,13 @@ int init_new_context(struct task_struct struct mm_struct * old_mm; int retval = 0; - init_MUTEX(&mm->context.sem); + mutex_init(&mm->context.lock); mm->context.size = 0; old_mm = current->mm; if (old_mm && old_mm->context.size > 0) { - down(&old_mm->context.sem); + mutex_lock(&old_mm->context.lock); retval = copy_ldt(&mm->context, &old_mm->context); - up(&old_mm->context.sem); + mutex_unlock(&old_mm->context.lock); } return retval; } @@ -132,7 +132,7 @@ static int read_ldt(void __user * ptr, u if (bytecount > LDT_ENTRY_SIZE*LDT_ENTRIES) bytecount = LDT_ENTRY_SIZE*LDT_ENTRIES; - down(&mm->context.sem); + mutex_lock(&mm->context.lock); size = mm->context.size*LDT_ENTRY_SIZE; if (size > bytecount) size = bytecount; @@ -140,7 +140,7 @@ static int read_ldt(void __user * ptr, u err = 0; if (copy_to_user(ptr, mm->context.ldt, size)) err = -EFAULT; - up(&mm->context.sem); + mutex_unlock(&mm->context.lock); if (err < 0) goto error_return; if (size != bytecount) { @@ -196,7 +196,7 @@ static int write_ldt(void __user * ptr, goto out; } - down(&mm->context.sem); + mutex_lock(&mm->context.lock); if (ldt_info.entry_number >= mm->context.size) { error = alloc_ldt(¤t->mm->context, ldt_info.entry_number+1, 1); if (error < 0) @@ -223,7 +223,7 @@ install: error = 0; out_unlock: - up(&mm->context.sem); + mutex_unlock(&mm->context.lock); out: return error; } --- linux-2.6-lcpt.orig/arch/i386/kernel/ptrace.c +++ linux-2.6-lcpt/arch/i386/kernel/ptrace.c @@ -166,7 +166,7 @@ static unsigned long convert_eip_to_line seg &= ~7UL; - down(&child->mm->context.sem); + mutex_lock(&child->mm->context.lock); if (unlikely((seg >> 3) >= child->mm->context.size)) addr = -1L; /* bogus selector, access would fault */ else { @@ -180,7 +180,7 @@ static unsigned long convert_eip_to_line addr &= 0xffff; addr += base; } - up(&child->mm->context.sem); + mutex_unlock(&child->mm->context.lock); } return addr; } --- linux-2.6-lcpt.orig/include/asm-i386/mmu.h +++ linux-2.6-lcpt/include/asm-i386/mmu.h @@ -1,7 +1,7 @@ #ifndef __i386_MMU_H #define __i386_MMU_H -#include +#include /* * The i386 doesn't have a mmu context, but * we put the segment information here. @@ -10,7 +10,7 @@ */ typedef struct { int size; - struct semaphore sem; + struct mutex lock; void *ldt; void *vdso; } mm_context_t; --- linux-2.6-lcpt.orig/arch/i386/kernel/i386_ksyms.c +++ linux-2.6-lcpt/arch/i386/kernel/i386_ksyms.c @@ -1,4 +1,5 @@ #include +#include #include #include --- linux-2.6-lcpt.orig/arch/i386/mm/fault.c +++ linux-2.6-lcpt/arch/i386/mm/fault.c @@ -110,7 +110,7 @@ static inline unsigned long get_segment_ LDT and other horrors are only used in user space. */ if (seg & (1<<2)) { /* Must lock the LDT while reading it. */ - down(¤t->mm->context.sem); + mutex_lock(¤t->mm->context.lock); desc = current->mm->context.ldt; desc = (void *)desc + (seg & ~7); } else { @@ -123,7 +123,7 @@ static inline unsigned long get_segment_ base = get_desc_base((unsigned long *)desc); if (seg & (1<<2)) { - up(¤t->mm->context.sem); + mutex_unlock(¤t->mm->context.lock); } else put_cpu(); -- Luiz Fernando N. 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