Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759434AbXKUQAn (ORCPT ); Wed, 21 Nov 2007 11:00:43 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1756475AbXKUQAM (ORCPT ); Wed, 21 Nov 2007 11:00:12 -0500 Received: from x346.tv-sign.ru ([89.108.83.215]:60028 "EHLO mail.screens.ru" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755977AbXKUQAK (ORCPT ); Wed, 21 Nov 2007 11:00:10 -0500 Date: Wed, 21 Nov 2007 19:00:26 +0300 From: Oleg Nesterov To: Andrew Morton Cc: Roland McGrath , linux-kernel@vger.kernel.org Subject: [PATCH -mm 1/3] kill PT_ATTACHED Message-ID: <20071121160026.GA1172@tv-sign.ru> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.5.11 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3132 Lines: 87 Since the patch "Fix ptrace_attach()/ptrace_traceme()/de_thread() race" commit f5b40e363ad6041a96e3da32281d8faa191597b9 we set PT_ATTACHED and change child->parent "atomically" wrt task_list lock. This means we can remove the checks like "PT_ATTACHED && ->parent != ptracer" which were needed to catch the "ptrace attach is in progress" case. We can also remove the flag itself since nobody else uses it. Signed-off-by: Oleg Nesterov --- PT/include/linux/ptrace.h~1_PT_ATTACHED 2007-11-21 16:41:25.000000000 +0300 +++ PT/include/linux/ptrace.h 2007-11-21 16:50:39.000000000 +0300 @@ -67,7 +67,6 @@ #define PT_TRACE_EXEC 0x00000080 #define PT_TRACE_VFORK_DONE 0x00000100 #define PT_TRACE_EXIT 0x00000200 -#define PT_ATTACHED 0x00000400 /* parent != real_parent */ #define PT_TRACE_MASK 0x000003f4 --- PT/kernel/ptrace.c~1_PT_ATTACHED 2007-11-21 16:41:25.000000000 +0300 +++ PT/kernel/ptrace.c 2007-11-21 16:53:39.000000000 +0300 @@ -100,8 +100,7 @@ int ptrace_check_attach(struct task_stru */ read_lock(&tasklist_lock); if ((child->ptrace & PT_PTRACED) && child->parent == current && - (!(child->ptrace & PT_ATTACHED) || child->real_parent != current) - && child->signal != NULL) { + child->signal != NULL) { ret = 0; spin_lock_irq(&child->sighand->siglock); if (is_task_stopped(child)) @@ -200,8 +199,7 @@ repeat: goto bad; /* Go */ - task->ptrace |= PT_PTRACED | ((task->real_parent != current) - ? PT_ATTACHED : 0); + task->ptrace |= PT_PTRACED; if (capable(CAP_SYS_PTRACE)) task->ptrace |= PT_PTRACE_CAP; --- PT/kernel/signal.c~1_PT_ATTACHED 2007-11-21 16:41:25.000000000 +0300 +++ PT/kernel/signal.c 2007-11-21 16:50:39.000000000 +0300 @@ -1577,11 +1577,6 @@ static inline int may_ptrace_stop(void) { if (!likely(current->ptrace & PT_PTRACED)) return 0; - - if (unlikely(current->parent == current->real_parent && - (current->ptrace & PT_ATTACHED))) - return 0; - /* * Are we in the middle of do_coredump? * If so and our tracer is also part of the coredump stopping --- PT/kernel/exit.c~1_PT_ATTACHED 2007-11-21 16:41:25.000000000 +0300 +++ PT/kernel/exit.c 2007-11-21 16:50:39.000000000 +0300 @@ -1511,18 +1511,7 @@ static int wait_task_continued(struct ta static inline int my_ptrace_child(struct task_struct *p) { - if (!(p->ptrace & PT_PTRACED)) - return 0; - if (!(p->ptrace & PT_ATTACHED)) - return 1; - /* - * This child was PTRACE_ATTACH'd. We should be seeing it only if - * we are the attacher. If we are the real parent, this is a race - * inside ptrace_attach. It is waiting for the tasklist_lock, - * which we have to switch the parent links, but has already set - * the flags in p->ptrace. - */ - return (p->parent != p->real_parent); + return p->ptrace & PT_PTRACED; } static long do_wait(pid_t pid, int options, struct siginfo __user *infop, - 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/