Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Mon, 18 Mar 2002 23:01:01 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Mon, 18 Mar 2002 23:00:52 -0500 Received: from 66-188-80-185.mad.wi.charter.com ([66.188.80.185]:56974 "EHLO localhost.localdomain") by vger.kernel.org with ESMTP id ; Mon, 18 Mar 2002 23:00:39 -0500 To: linux-kernel@vger.kernel.org Cc: "Mike Coleman" , marcelo@conectiva.com.br, torvalds@transmeta.com, alan@lxorguk.ukuu.org.uk, hirofumi@mail.parknet.co.jp Subject: Re: [PATCH] ptrace on stopped processes (2.4) In-Reply-To: <87g0632lzw.fsf@mathdogs.com> <87665wbdtf.fsf@mathdogs.com> From: vic Date: Mon, 18 Mar 2002 21:59:51 -0600 Message-ID: Lines: 64 User-Agent: Gnus/5.090004 (Oort Gnus v0.04) Emacs/20.7 MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org This is a repost of the ptrace patch to 2.4 kernels we've discussed in recent months. Since the last post, I have updated it to linux 2.4.18 (no changes) and tested it with subterfuge and uml. Subterfuge seems to be unaffected. UML needs minor modifications; I've discussed them with Jeff Dike and (I believe) he is happy. I believe I have addressed everyone's concerns. The patch fixes these two bugs: 1. gdb and other tools cannot attach to a stopped process. The wait that follows the PTRACE_ATTACH will block indefinitely. 2. It is not possible to use PTRACE_DETACH to leave a process stopped, because ptrace ignores SIGSTOPs sent by the tracing process. Vic --- /home/vic/p/linux-2.4.18.orig/kernel/ptrace.c Wed Mar 13 13:14:54 2002 +++ /home/vic/p/linux-2.4.18/kernel/ptrace.c Mon Mar 18 21:58:11 2002 @@ -54,6 +54,7 @@ int ptrace_attach(struct task_struct *task) { + int stopped; task_lock(task); if (task->pid <= 1) goto bad; @@ -90,7 +91,13 @@ } write_unlock_irq(&tasklist_lock); + stopped = (task->state == TASK_STOPPED); send_sig(SIGSTOP, task, 1); + /* If it was stopped when we got here, + clear the pending SIGSTOP. */ + if (stopped) + wake_up_process(task); + return 0; bad: --- /home/vic/p/linux-2.4.18.orig/arch/i386/kernel/signal.c Wed Mar 13 13:16:44 2002 +++ /home/vic/p/linux-2.4.18/arch/i386/kernel/signal.c Wed Mar 13 16:31:38 2002 @@ -620,9 +620,9 @@ continue; current->exit_code = 0; - /* The debugger continued. Ignore SIGSTOP. */ - if (signr == SIGSTOP) - continue; + /* The debugger continued. */ + if (signr == SIGSTOP && current->ptrace & PT_PTRACED) + continue; /* ignore SIGSTOP */ /* Update the siginfo structure. Is this good? */ if (signr != info.si_signo) { - 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/